0:00:02 > 0:00:03Doughnuts, £1 each now.
0:00:03 > 0:00:04Fat -
0:00:04 > 0:00:08it's in all the food we love to eat.
0:00:08 > 0:00:11'There's nothing that tastes quite so good.'
0:00:11 > 0:00:13I could ad-lib on cheese forever.
0:00:13 > 0:00:16'But it's a love-hate relationship.'
0:00:16 > 0:00:20It's naughty, cos it's all fried.
0:00:20 > 0:00:25'We're terrified about what it does to our bodies and our health.'
0:00:25 > 0:00:29Fat has a reputation of being public health enemy number one,
0:00:29 > 0:00:33but is it really as terrible as we've come to believe?
0:00:33 > 0:00:35'I'm Saleyha Ahsan and I'm a doctor,
0:00:35 > 0:00:39'but I've got more than a professional interest in fat,
0:00:39 > 0:00:42'because I've discovered I'm carrying far more
0:00:42 > 0:00:44'than is good for me.'
0:00:44 > 0:00:47I'm nearly double what I should be.
0:00:47 > 0:00:49'So I'm on a mission to find out
0:00:49 > 0:00:52'whether fat is really the devil it seems.
0:00:52 > 0:00:55'I'm going to look into the very latest science
0:00:55 > 0:00:57'and uncover some surprises.'
0:00:57 > 0:00:58That's pretty amazing.
0:01:00 > 0:01:06'I'll find out which saturated fats might be good for us after all,
0:01:06 > 0:01:10'reveal the shortcut to burning fat long after we stop exercising...'
0:01:10 > 0:01:11Off you go.
0:01:11 > 0:01:15'..and discover the strange fat that might be added
0:01:15 > 0:01:18'to the food of the future to make us healthier.'
0:01:18 > 0:01:19It's...
0:01:19 > 0:01:21It's really salty.
0:01:21 > 0:01:24I think we can be smarter about fat,
0:01:24 > 0:01:26both in our food
0:01:26 > 0:01:28and in our bodies.
0:01:28 > 0:01:30It's time to discover
0:01:30 > 0:01:32the truth about fat.
0:01:38 > 0:01:41'As a nation, we're utterly confused about fat.
0:01:43 > 0:01:46'And I see that confusion wherever I go.
0:01:46 > 0:01:50'Take the weird new fad hitting our coffee shops,
0:01:50 > 0:01:51'where a nice hot brew
0:01:51 > 0:01:55'now comes with a big lump of butter.'
0:01:55 > 0:01:58When I first heard about this coffee, I couldn't believe it,
0:01:58 > 0:02:01BUT I won't judge it until I've actually tried it.
0:02:04 > 0:02:07'It looks like a heart attack in a cup.
0:02:07 > 0:02:09'Coffee, butter
0:02:09 > 0:02:12'and a shot of palm and coconut oil, for good measure.
0:02:12 > 0:02:17'The idea is it's supposed to keep your energy levels up for hours.'
0:02:17 > 0:02:21I normally only ever have a weak white coffee,
0:02:21 > 0:02:26so I'm really interested to see the effects of this dollop of butter.
0:02:26 > 0:02:27In fact, two dollops.
0:02:30 > 0:02:31Thank you, thank you.
0:02:31 > 0:02:33This just doesn't feel right.
0:02:33 > 0:02:37For decades, we've been told to avoid saturated fat
0:02:37 > 0:02:39to stay healthy.
0:02:39 > 0:02:43And in here, it's something like my entire day's allowance,
0:02:43 > 0:02:44so it better be worth it.
0:02:46 > 0:02:47Let me give it a go.
0:02:50 > 0:02:51Eurgh, right.
0:02:51 > 0:02:54I'm meant to be a bit more diplomatic but I can't lie!
0:02:54 > 0:02:56Cos, I mean, it tastes like coffee...
0:02:58 > 0:03:01..but you've just got to be prepared for that
0:03:01 > 0:03:03funny, oily sensation on your lips.
0:03:08 > 0:03:12I think the reason why people are throwing caution to the wind
0:03:12 > 0:03:14and dolloping their butter into their coffee
0:03:14 > 0:03:16is because of headlines like this.
0:03:17 > 0:03:21'Over the last few years, we've seen reports that suggest
0:03:21 > 0:03:23'we've got it wrong about fat,
0:03:23 > 0:03:26'that it isn't as bad as we think,
0:03:26 > 0:03:28'and that even the worst offender,
0:03:28 > 0:03:30'saturated fat,
0:03:30 > 0:03:32'might actually be good for us.
0:03:32 > 0:03:34'So, what should we believe?'
0:03:36 > 0:03:37It's so complicated,
0:03:37 > 0:03:40and even for me as a doctor,
0:03:40 > 0:03:42I find it challenging.
0:03:42 > 0:03:44'So, to clear up all this confusion,
0:03:44 > 0:03:49'I'm going to dig into the very latest science about fat.'
0:03:53 > 0:03:55'First, I've come to Aberdeen.
0:03:55 > 0:03:59'We've taken over a country house outside the city
0:03:59 > 0:04:02'and brought in a group of volunteers.
0:04:02 > 0:04:05'We're going to put them through a unique set of experiments
0:04:05 > 0:04:07'all involving fat.
0:04:08 > 0:04:09'They won't find it easy.
0:04:09 > 0:04:12'In fact, they're in for a few shocks.
0:04:12 > 0:04:14'But it will help us find out
0:04:14 > 0:04:16'whether fat is really bad for us,
0:04:16 > 0:04:18'or good for us.'
0:04:18 > 0:04:19Hello.
0:04:19 > 0:04:22'Like me, our volunteers are bamboozled
0:04:22 > 0:04:27'by all the different things they hear about fat.'
0:04:27 > 0:04:29I think it's confusing because there are so many different fats.
0:04:29 > 0:04:33Yeah, definitely, cos you get stuff that's, like, reduced fat
0:04:33 > 0:04:36and low fat, and zero fat, and actually,
0:04:36 > 0:04:39something that's reduced fat still has a lot of fat in it.
0:04:39 > 0:04:42You're nodding in agreement, Daisy, what do you think?
0:04:42 > 0:04:43I think we all want to be healthy,
0:04:43 > 0:04:46but there's a lot of mixed messages out there.
0:04:46 > 0:04:50The best way would be to simplify things so people just know
0:04:50 > 0:04:51this is wrong, this is right.
0:04:51 > 0:04:53I tend just to look at foods
0:04:53 > 0:04:55and not obsess about the fat content in them.
0:04:55 > 0:04:59There's so much in magazines now about which latest celebrity
0:04:59 > 0:05:02is following which diet, no carbs, no fat.
0:05:02 > 0:05:03It's really confusing.
0:05:09 > 0:05:13Perhaps the confusion starts with the word "fat" itself.
0:05:13 > 0:05:16It can mean more than one thing.
0:05:16 > 0:05:18The fat on our plate
0:05:18 > 0:05:20or the fat in our bodies.
0:05:20 > 0:05:22So the question is,
0:05:22 > 0:05:24when we eat fat,
0:05:24 > 0:05:26what happens inside us?
0:05:29 > 0:05:32'To find out, we've served up four very different meals
0:05:32 > 0:05:34'for four of our volunteers.
0:05:35 > 0:05:40'A pizza topped with cheese that's full of dairy fat,
0:05:40 > 0:05:45'a salad of avocado and salmon and oily fish,
0:05:45 > 0:05:48'a greasy burger and chips,
0:05:48 > 0:05:50'and a small bowl of nuts,
0:05:50 > 0:05:52'rich in natural fats.'
0:05:52 > 0:05:55- Could you honestly eat pizza for your breakfast?- No.
0:05:55 > 0:05:58- That's quite continental. - Burger and chips, though.
0:05:58 > 0:05:59That's a good way to start the day.
0:05:59 > 0:06:03'It's the first thing they've eaten in 12 hours.'
0:06:03 > 0:06:04Right, guys.
0:06:04 > 0:06:06ALL: Hi.
0:06:06 > 0:06:08Lots of food in front of you all.
0:06:08 > 0:06:10I know you've not eaten since last night
0:06:10 > 0:06:12because we're going to do some tests on you.
0:06:12 > 0:06:14So, I'm not going to hold you up.
0:06:14 > 0:06:16Tuck in, bon appetit.
0:06:16 > 0:06:17ALL: Thank you.
0:06:19 > 0:06:22I'm fair chuffed with my salmon, it's lovely. Nice.
0:06:23 > 0:06:28'All these foods contain fat, but they're obviously different.
0:06:28 > 0:06:32'So I want to know which of them puts the most fat into our bodies.
0:06:32 > 0:06:37'To find out, we're taking a blood sample from each volunteer.'
0:06:37 > 0:06:38Sharp scratch, there we go.
0:06:39 > 0:06:42'Dr Emilie Combet is an expert in nutrition
0:06:42 > 0:06:45'from Glasgow University.
0:06:45 > 0:06:48'She's going to test how much fat is in their blood
0:06:48 > 0:06:50'before and after they've eaten their meal.'
0:06:50 > 0:06:53What we have here are your blood tests.
0:06:54 > 0:06:58So, what we did, we took your blood before your meal and after the meal,
0:06:58 > 0:07:00so several time points.
0:07:00 > 0:07:02And that's a normal sample of blood.
0:07:02 > 0:07:05So, you see, it's red, it's healthy,
0:07:05 > 0:07:07and what we do with those blood tubes,
0:07:07 > 0:07:09we put them in the centrifuge
0:07:09 > 0:07:12and that's a machine that is going to spin those tubes very fast.
0:07:12 > 0:07:16And what we obtain at the end is a sample like that.
0:07:16 > 0:07:19And what we can see, at the bottom, we've got our red blood cells.
0:07:19 > 0:07:22And on top, we've got this yellow, clear layer,
0:07:22 > 0:07:24which is plasma.
0:07:24 > 0:07:27So, your blood would look like that in the morning
0:07:27 > 0:07:30when you haven't eaten, for example.
0:07:30 > 0:07:32'Now to see how the different fatty meals
0:07:32 > 0:07:35'have affected our volunteers' blood.'
0:07:35 > 0:07:39So, which one of the meals did you think had the most fat in them?
0:07:39 > 0:07:40I think what I had, the burger and chips,
0:07:40 > 0:07:42might have been the most fatty.
0:07:42 > 0:07:44Yours, yeah? Your burger and chips?
0:07:44 > 0:07:47I think it would be the burger and chips.
0:07:47 > 0:07:48Right.
0:07:48 > 0:07:52Let's have a look at the blood after having eaten a burger and chips.
0:07:52 > 0:07:53Yeah.
0:07:53 > 0:07:56- Well, here it is.- Oh.
0:07:56 > 0:07:59- What do you think, Dave?- Well, it's a lot more cloudy, isn't it?
0:07:59 > 0:08:01Uh-huh, the cloudiness comes from that fat,
0:08:01 > 0:08:03the fat has gone into your blood.
0:08:03 > 0:08:06So the actual cloudiness that we're seeing here
0:08:06 > 0:08:08is the fat that Dave ate.
0:08:08 > 0:08:10That fat passed into his blood
0:08:10 > 0:08:13and creates the cloudiness, exactly.
0:08:13 > 0:08:16- Wow.- It doesn't make me want to eat a burger and chips again, very soon.
0:08:18 > 0:08:20'So after Dave's burger and chips,
0:08:20 > 0:08:22'his blood is cloudy with fat.
0:08:23 > 0:08:25'But how much fat did the others get
0:08:25 > 0:08:29'from the healthier looking nuts or salmon?
0:08:29 > 0:08:32'They're hoping their samples won't look so cloudy.'
0:08:32 > 0:08:34I bet you're all dying to find out.
0:08:37 > 0:08:38What do you think?
0:08:38 > 0:08:40They're not looking good.
0:08:40 > 0:08:44But the big surprise is that all your samples are cloudy.
0:08:44 > 0:08:47I think a lot of people would be quite shocked, actually,
0:08:47 > 0:08:50that the fat that you've eaten has gone so quickly
0:08:50 > 0:08:53and so directly into your bloodstream.
0:08:53 > 0:08:55Mm-hm.
0:08:55 > 0:08:57And in fact, when we eat the food,
0:08:57 > 0:09:00the fat is almost entirely absorbed by the blood.
0:09:00 > 0:09:0295% goes into the blood.
0:09:04 > 0:09:06'So, whether it's a healthy salmon salad
0:09:06 > 0:09:08'or a greasy burger and chips,
0:09:08 > 0:09:12'every bit of fat we eat ends up in our blood.
0:09:13 > 0:09:16'Our bodies are built to squeeze all the fat
0:09:16 > 0:09:19'from every different food we put in our mouth.
0:09:19 > 0:09:22'But where it starts to get really interesting
0:09:22 > 0:09:24'is what happens next.'
0:09:28 > 0:09:33'It's often said that fat goes straight from our lips to our hips,
0:09:33 > 0:09:37'but the truth about what happens to the fat in our body
0:09:37 > 0:09:39'is far more interesting.
0:09:39 > 0:09:42'And to show you, I'm going to use myself.'
0:09:42 > 0:09:46OK, so it's now time to talk about my weight.
0:09:46 > 0:09:49Over the last few years, I've been getting fatter.
0:09:49 > 0:09:52I used to do a lot of running, but I've now got an ankle injury,
0:09:52 > 0:09:56but I haven't changed the way that I'm eating.
0:09:56 > 0:10:00So as a consequence, there's rather more of me here today
0:10:00 > 0:10:01than there was before.
0:10:03 > 0:10:08'I want to see just how much fat is in my body and where it is,
0:10:08 > 0:10:09'so I'm having an MRI scan.'
0:10:11 > 0:10:15We scan you from the top of your head, all the way to your feet.
0:10:15 > 0:10:20I think it's going to be a real "mirror, mirror on the wall" moment,
0:10:20 > 0:10:22"who's the fattest of them all?"
0:10:22 > 0:10:26Well, it'll be a good measurement of how much fat you have
0:10:26 > 0:10:29and the distribution of that fat.
0:10:29 > 0:10:33So, all this white bit here is all your fat around your body.
0:10:33 > 0:10:35It's quite something, actually, to see
0:10:35 > 0:10:38your own body right from the inside.
0:10:41 > 0:10:45'The first kind of fat I can see is a thick layer all around my body,
0:10:45 > 0:10:47'just under the skin.'
0:10:47 > 0:10:51Oh, my God! Got it right around my hips.
0:10:51 > 0:10:53'That's the stuff I can pinch
0:10:53 > 0:10:56'and I can see I've got far too much of it.'
0:10:58 > 0:11:01I'm really not doing myself any favours, at all.
0:11:01 > 0:11:05'But that's not the only place we've got fat in our body.
0:11:05 > 0:11:09'Now Jimmy shows me a different view from the scan.'
0:11:09 > 0:11:10So, we're looking from the top...
0:11:10 > 0:11:14'Looking straight down from the top, this is my abdomen,
0:11:14 > 0:11:20'where my organs are, and all that white stuff around them...is fat.'
0:11:20 > 0:11:24Oh, my God, that's pretty revolting.
0:11:24 > 0:11:27As you can see, your organs are literally kind of surrounded,
0:11:27 > 0:11:29embedded within the internal fat.
0:11:29 > 0:11:31It's like they are in a sea of fat.
0:11:31 > 0:11:35I just find that, just really horrible. Really awful.
0:11:35 > 0:11:39- OK, so your percentage body fat is 43%.- And what's the normal?
0:11:39 > 0:11:41Between 20% and 22%.
0:11:41 > 0:11:43I'm nearly double what I should be?
0:11:43 > 0:11:47- It is something that you have to be concerned about...- Yeah, absolutely.
0:11:47 > 0:11:48Absolutely.
0:11:48 > 0:11:54I think it's the thought of having fat in my liver that just fills me
0:11:54 > 0:11:58with dread, actually, cos that's really not healthy at all.
0:11:58 > 0:12:01'Too much fat within our tummies
0:12:01 > 0:12:05'is more dangerous than too much under the skin.
0:12:05 > 0:12:09'It can lead to diabetes and heart disease.'
0:12:09 > 0:12:16Seeing the way that fat is coating nearly all of my organs...
0:12:16 > 0:12:19This is a huge wake-up call for me.
0:12:20 > 0:12:25It's almost enough to put me off eating fatty food ever again.
0:12:26 > 0:12:29And yet, I also know that in a healthy diet
0:12:29 > 0:12:34around a third of the calories we eat should come from fat.
0:12:34 > 0:12:35It's crucial stuff.
0:12:38 > 0:12:41And to show you why it's so important,
0:12:41 > 0:12:46we're about to ask our volunteers to do something extraordinary.
0:12:50 > 0:12:56So, what I'd really like to do is to ask you to step away from the fat,
0:12:56 > 0:12:59to give it up for a whole week.
0:12:59 > 0:13:01So that's seven days, no fat.
0:13:01 > 0:13:04- Who's up for it?- Yeah, that's OK.
0:13:04 > 0:13:07- Yeah, bring it on, I like a challenge.- Great.
0:13:09 > 0:13:13As a scientist, I know that often the best way to understand
0:13:13 > 0:13:17what something is doing is to take it away.
0:13:17 > 0:13:19So we're going to strip all the fat
0:13:19 > 0:13:24out of our volunteers' diet to see how it affects their body and mind.
0:13:25 > 0:13:30It's a bold and challenging thing we're asking our volunteers to do.
0:13:30 > 0:13:33Overdoing the fat's easy, as many of us know,
0:13:33 > 0:13:37but underdoing it, now that's another story.
0:13:37 > 0:13:40Very few of us have experienced that.
0:13:40 > 0:13:42They're going to find it tough.
0:13:42 > 0:13:46I know I love crisps and I would eat six bags, one after the other,
0:13:46 > 0:13:47if I could.
0:13:47 > 0:13:50I think it's going to be tough for me
0:13:50 > 0:13:53to not have that kind of go-to pick-me-up,
0:13:53 > 0:13:58but I think the hard part as well is going to be how to make a meal.
0:13:58 > 0:14:02I'm obviously a girl who loves her food, so it's going to be
0:14:02 > 0:14:07interesting to see how having zero fat for a week is going to be.
0:14:07 > 0:14:09I think it'll be hard.
0:14:11 > 0:14:12I do think it will be hard.
0:14:12 > 0:14:15Going to have to be quite strict with myself.
0:14:17 > 0:14:21But what our volunteers don't yet realise is that this will be
0:14:21 > 0:14:24a test of far more than their willpower.
0:14:24 > 0:14:28The latest science suggests that living without fat
0:14:28 > 0:14:32will affect their body and mind in unexpected ways -
0:14:32 > 0:14:36some of them weird, some of them frankly rather unpleasant.
0:14:36 > 0:14:41So they've all had to have medical checks and be cleared to take part.
0:14:44 > 0:14:48'The first question is - what CAN they eat?
0:14:48 > 0:14:53'We need to hunt down the everyday foods with the least fat.'
0:14:53 > 0:14:58OK, team, what I want you to do is arrange these foods in order
0:14:58 > 0:15:03of fat content with what you think is 0% at this end
0:15:03 > 0:15:06and what you think is over 50% at that end
0:15:06 > 0:15:09and then everything in between.
0:15:09 > 0:15:11Ready? Off you go.
0:15:11 > 0:15:14Shall we do the extremes first, the low-fat and high-fat?
0:15:14 > 0:15:16- Yeah, it might be easier. - This'll be high...
0:15:16 > 0:15:18They're going to be high, aren't they?
0:15:18 > 0:15:20Everything I want to eat is going to be up there.
0:15:20 > 0:15:22Will we take the butter up here as well?
0:15:22 > 0:15:25That's the turkey, that probably needs to go down...
0:15:25 > 0:15:29'Keeping an eye on our volunteers is dietician Lucy Jones.'
0:15:29 > 0:15:31No, I think it will be this lot.
0:15:31 > 0:15:33Yeah, maybe sort of 5% or so...
0:15:33 > 0:15:37So, Lucy, cutting out fat from your diet is actually easier said
0:15:37 > 0:15:38than done, isn't it?
0:15:38 > 0:15:42It really is and what we're about to find out is that fat is
0:15:42 > 0:15:46present in so many different foods, ones we don't even think about,
0:15:46 > 0:15:50so trying to adopt a diet that's basically fat-free
0:15:50 > 0:15:52is incredibly difficult in practice.
0:15:52 > 0:15:54Between one and five?
0:15:54 > 0:15:57- I think it will be lower than that. - Yeah, I think only maybe one, or...
0:15:57 > 0:16:00'Very few foods contain no fat at all.
0:16:00 > 0:16:06'Almost everything is a mixture of protein, carbohydrate and fat -
0:16:06 > 0:16:10'the three basic building blocks of a healthy diet.
0:16:10 > 0:16:13'Even vegetables contain a bit of fat,
0:16:13 > 0:16:17'so to make sure our volunteers have something to eat this week,
0:16:17 > 0:16:21'we're allowing them anything with less than 1% fat.'
0:16:21 > 0:16:23- They're yummy sweeties. - They must be up here.
0:16:23 > 0:16:26No, I don't think so, cos these are, like, just sugar-based.
0:16:26 > 0:16:27It's all sugar, isn't it?
0:16:27 > 0:16:31If you cut out fat, what's going to happen to them?
0:16:31 > 0:16:32Well, that's going to be
0:16:32 > 0:16:35one of the really interesting things to watch...
0:16:35 > 0:16:36Oh, what about this?
0:16:36 > 0:16:39..because they're going to be quite restricted in terms of what
0:16:39 > 0:16:41they can eat, and I think that means through a day,
0:16:41 > 0:16:43they're going to end up eating less.
0:16:43 > 0:16:47So it'll be quite interesting how hungry they get in the week.
0:16:47 > 0:16:51- Anything we need to change? - Very little in the middle. - Looks about right for down there.
0:16:51 > 0:16:53- Last change? Last change.- OK.
0:16:53 > 0:16:55- Guys - confident, happy? - ALL: Yeah.
0:16:55 > 0:16:56- No more changes?- No.
0:16:56 > 0:16:58Right, OK.
0:16:58 > 0:17:00There are a couple of quite shocking surprises.
0:17:00 > 0:17:03Now, these cream crackers are actually...
0:17:03 > 0:17:05around here.
0:17:05 > 0:17:08That's way down, that's past the 10%.
0:17:08 > 0:17:12That's right, so they're about 13% fat, cream crackers.
0:17:12 > 0:17:14Wow, even more than our Jaffas?
0:17:14 > 0:17:16Yes, actually, the Jaffa Cakes
0:17:16 > 0:17:18- are in the wrong position.- OK.
0:17:18 > 0:17:21They only need to move to about here, about 8%.
0:17:21 > 0:17:25The nuts, which you guys have placed at around 10% -
0:17:25 > 0:17:2650% fat.
0:17:26 > 0:17:28- What?! - It's neck and neck with the butter.
0:17:28 > 0:17:31- It's not neck and neck with the butter.- Oh, is it not?
0:17:31 > 0:17:32So the butter should be actually over here!
0:17:32 > 0:17:34Off the table, off the table.
0:17:34 > 0:17:35- So, the butter's around 80%.- Wow.
0:17:35 > 0:17:40An avocado - super healthy, full of monounsaturated fats.
0:17:40 > 0:17:43They're actually slightly higher in fat than the sausage rolls.
0:17:43 > 0:17:45Wow.
0:17:45 > 0:17:47What about the cereals?
0:17:47 > 0:17:50Yeah, cornflakes actually have about 0.9% fat,
0:17:50 > 0:17:53- so they'd be right down here with the allowed foods...- Wow.
0:17:53 > 0:17:55..where the wheat-based cereal has about 2%
0:17:55 > 0:17:57because it is whole-wheat.
0:17:57 > 0:18:00So, cornflakes is in, guys, tons of these.
0:18:00 > 0:18:02- Yeah, I'm quite happy about that. - Who wants one?
0:18:02 > 0:18:04ALL LAUGH
0:18:04 > 0:18:07I think the sweets being allowed in your week just help to clarify
0:18:07 > 0:18:10that this isn't necessarily about health, this is just
0:18:10 > 0:18:13about getting the fat out of your diet and seeing the effects of that.
0:18:15 > 0:18:21So, now, our volunteers are off for their first fat-free shop.
0:18:21 > 0:18:23They can choose what they want
0:18:23 > 0:18:25so long as it's below the magic 1% fat.
0:18:25 > 0:18:28Those are...
0:18:28 > 0:18:301.7, so I can't have those.
0:18:32 > 0:18:35Their weird regime for the week could include...
0:18:35 > 0:18:39fat-free dairy, like yoghurt and skimmed milk,
0:18:39 > 0:18:43lentils, beans and pulses,
0:18:43 > 0:18:45or sweets and jelly.
0:18:45 > 0:18:50Cornflakes are on the menu, but wholegrain cereal is not...
0:18:50 > 0:18:51Oh, too much.
0:18:51 > 0:18:53..owing to the oily wheat germ in it.
0:18:53 > 0:18:55No, not even them.
0:18:56 > 0:18:59And surprisingly, bread is out too.
0:19:01 > 0:19:04Chicken breast is off limits, as are most meats.
0:19:04 > 0:19:07But some lean fish will be fine.
0:19:07 > 0:19:09Actually, Quorn meatballs sounds...OK.
0:19:09 > 0:19:13The weekly shop has become a bit of a nightmare.
0:19:13 > 0:19:15No meatballs for me.
0:19:19 > 0:19:21Quite interesting to shop hungry
0:19:21 > 0:19:24and know that you couldn't buy any fatty foods at the same time.
0:19:24 > 0:19:27I've got rice vermicelli.
0:19:27 > 0:19:31A few onions, carrot, lentil and orange soup.
0:19:31 > 0:19:36I went and I bought sweeties just because I knew I could!
0:19:36 > 0:19:39- SHE GASPS - "Fat - nil."
0:19:39 > 0:19:41I don't know how easy it's going to be to do this this week
0:19:41 > 0:19:45because I was really surprised there's fat in porridge.
0:19:45 > 0:19:49We're going to monitor our volunteers through the week
0:19:49 > 0:19:51to see how cutting fat out completely
0:19:51 > 0:19:55affects their body and mind.
0:19:55 > 0:19:59It would be fair to have described that as a joyless experience.
0:20:07 > 0:20:11'One of their first surprises will be what happens in their mouth.'
0:20:12 > 0:20:17'Dr Andy Connelly is a chemist with a fascination for food.'
0:20:17 > 0:20:18Hello, Andy.
0:20:18 > 0:20:22'He wants to show me some of the hidden powers of fat.'
0:20:23 > 0:20:26'First up, two glasses of milk.
0:20:26 > 0:20:31'One full-fat, one skimmed and fat-free.
0:20:31 > 0:20:33'Add a dash of vanilla extract to each.'
0:20:33 > 0:20:36Give 'em a bit of a stir just to mix it in.
0:20:36 > 0:20:38We'll start with the skimmed milk.
0:20:38 > 0:20:41It smells vanilla-y.
0:20:44 > 0:20:48And it doesn't taste great at all. It tastes like medicine. Yuck!
0:20:48 > 0:20:49It doesn't taste like vanilla.
0:20:49 > 0:20:52Try the full-fat one and see what the difference is.
0:20:55 > 0:20:56That... That tastes like vanilla.
0:20:56 > 0:20:59That tastes like some sort of milkshake.
0:20:59 > 0:21:02Yes, it's much more pleasant and it's all because
0:21:02 > 0:21:06the fats affect the transfer of flavour into your mouth.
0:21:06 > 0:21:08'In the full-cream milk on the right,
0:21:08 > 0:21:12'droplets of fat soak up the vanilla flavour like a sponge
0:21:12 > 0:21:17'and release it quite gradually when I taste it.
0:21:17 > 0:21:19'In the skimmed milk, where there's no fat,
0:21:19 > 0:21:22'the flavour is released much more suddenly.'
0:21:22 > 0:21:24So, in the warmth of your mouth, suddenly you've got
0:21:24 > 0:21:27this flavour that isn't quite right because it hits you so quickly.
0:21:27 > 0:21:30Whereas when you've got the fat, it goes into your mouth and
0:21:30 > 0:21:33cos it's a sponge, it releases the flavour, but only slowly.
0:21:33 > 0:21:37So it fills your mouth, it's much more pleasant.
0:21:37 > 0:21:38And also, milk is very thick,
0:21:38 > 0:21:42so it coats the inside of your mouth and the flavours stay in your mouth
0:21:42 > 0:21:45much longer, and it's a much more pleasant experience.
0:21:45 > 0:21:48That's just so unbelievable. I would never have guessed that.
0:21:48 > 0:21:53I can't believe how weird that tastes, it's gross!
0:21:53 > 0:21:55It's so gross. So gross, I'm going to try it again.
0:21:55 > 0:21:57HE CHUCKLES Rather you than me.
0:21:57 > 0:21:59Cos it just, it's so bizarre.
0:21:59 > 0:22:00- Yeah.- Yuck!
0:22:00 > 0:22:03Isn't that clever? That's really clever. Clever old milk.
0:22:03 > 0:22:05It is, amazing, yeah, yeah.
0:22:08 > 0:22:13'So, fat really affects the way food tastes,
0:22:13 > 0:22:17'altering how flavours are released and linger in our mouth.
0:22:17 > 0:22:20'But there's another way fat can change food.'
0:22:20 > 0:22:25- It's been absolutely ages since I've made chips.- Yeah, me too, me too.
0:22:25 > 0:22:27But I'm tempted to start doing it again.
0:22:27 > 0:22:29SHE LAUGHS
0:22:29 > 0:22:33'When we fry food, we create a special kind of crispiness.'
0:22:33 > 0:22:37- They actually look ready.- They look lovely and brown, just ready to eat.
0:22:37 > 0:22:40'A crispiness that's almost impossible to achieve
0:22:40 > 0:22:41'any other way.'
0:22:41 > 0:22:45- OK, I'm going to go for... That's quite a crispy one.- Yeah.
0:22:47 > 0:22:49- That's really nice.- Mm.
0:22:49 > 0:22:52So, they're quite brown and crispy-looking on the outside
0:22:52 > 0:22:55and on the inside... fluffy and soft, why is that?
0:22:55 > 0:22:59Well, it's all down to the difference between fat and water.
0:22:59 > 0:23:03When we cook with water, we cook at the boiling point, about 100 degrees.
0:23:03 > 0:23:07- In fact, we go up to 180, 190 degrees.- That's almost twice.
0:23:07 > 0:23:11Exactly, yeah. So when we lower it in, you can hear...
0:23:13 > 0:23:17..all that water boiling away from the surface of the potato.
0:23:17 > 0:23:20So, that bubbling is actually water coming off the potato?
0:23:20 > 0:23:21Exactly, yeah.
0:23:21 > 0:23:24It's the steam coming off the surface of the potato, drying it out
0:23:24 > 0:23:27and making it really nice and crisp.
0:23:29 > 0:23:33'The hot oil dries out the surface of the potato in seconds,
0:23:33 > 0:23:37'much quicker than any other way of cooking.
0:23:37 > 0:23:43'And this creates the crispy coating around a soft, squishy inside,
0:23:43 > 0:23:45'that makes the perfect chip.
0:23:45 > 0:23:48'And there's something else the oil is doing.'
0:23:48 > 0:23:51What's also happening at these really high temperatures
0:23:51 > 0:23:53is there's all sorts of reactions happening on the surface
0:23:53 > 0:23:55of the potato, making it brown,
0:23:55 > 0:23:58and creating loads of fantastic flavours
0:23:58 > 0:23:59that make chips taste so great.
0:24:01 > 0:24:04'So the reason we love fat so much starts in our mouth,
0:24:04 > 0:24:08'thanks to the textures and flavours it can create.
0:24:08 > 0:24:12'But it's what happens next that shows just why fat
0:24:12 > 0:24:15'has such a powerful hold over us.'
0:24:19 > 0:24:23It has recently been discovered that from the instant we put something
0:24:23 > 0:24:29fatty in our mouth, surprising things begin to happen in our brain.
0:24:30 > 0:24:35And our brain is where fat really exerts its hidden power
0:24:35 > 0:24:37over our lives.
0:24:37 > 0:24:42To show me, Dr Fabian Grabenhorst has a bizarre-looking experiment.
0:24:42 > 0:24:45What you have here is different types of milkshakes,
0:24:45 > 0:24:47which differ in their fat content.
0:24:47 > 0:24:49So some are fatty, others are not so fatty,
0:24:49 > 0:24:52and these are computer-controlled juice pumps, which can pump
0:24:52 > 0:24:56the liquid through these tubes, straight into your mouth.
0:24:56 > 0:24:59- OK, and it's rigged up to this computer?- Right.
0:24:59 > 0:25:01Every time you taste a liquid, it can tell us
0:25:01 > 0:25:05how much you liked it and how fatty you thought the liquid was.
0:25:05 > 0:25:06OK, cool.
0:25:06 > 0:25:07- Should we give it a go?- I think so.
0:25:08 > 0:25:12'Without knowing which is which, I have to score the milkshakes
0:25:12 > 0:25:14'by how much I like them.'
0:25:15 > 0:25:18Oh, I didn't like that one. That tastes a bit like medicine.
0:25:18 > 0:25:20- Do you want to have another go? - Yeah.
0:25:20 > 0:25:25'And, you guessed it - it turns out I like the fattier ones most.'
0:25:26 > 0:25:30'Fabian ran this test on a bigger group of people
0:25:30 > 0:25:33'and scanned their brains at the same time.
0:25:33 > 0:25:36'And he saw something remarkable.
0:25:36 > 0:25:40'Within half a second of the higher-fat milkshake
0:25:40 > 0:25:44'touching their tongue, their brains reacted to it.'
0:25:45 > 0:25:48So these signals come in from the tongue
0:25:48 > 0:25:51and this part of the brain detects whether there's fat in the mouth.
0:25:54 > 0:25:56'Then, he saw a second response,
0:25:56 > 0:26:01'this time in a deeper part of the brain that registers pleasure.'
0:26:03 > 0:26:06It's an interesting part of the brain
0:26:06 > 0:26:10because it's often associated with emotional processing and sometimes
0:26:10 > 0:26:14it's also associated specifically with unconscious processing.
0:26:16 > 0:26:20It seems we're "hard-wired" to love fat.
0:26:22 > 0:26:26In prehistoric times, this could have helped us survive,
0:26:26 > 0:26:28driving us to hunt down fatty foods
0:26:28 > 0:26:31to keep us going when food was scarce.
0:26:32 > 0:26:37Today, we still have an in-built urge to seek out fat
0:26:37 > 0:26:40and this makes it hard for us to resist.
0:26:40 > 0:26:43When we give in to temptation,
0:26:43 > 0:26:46perhaps it's not so much a lack of willpower
0:26:46 > 0:26:48as a powerful, primitive impulse.
0:26:52 > 0:26:55And if we're completely deprived of fat,
0:26:55 > 0:26:59we soon begin to struggle, as our volunteers are finding out.
0:26:59 > 0:27:01Eating no fat...
0:27:02 > 0:27:07I don't think it's annoying, but it's... It's not exciting.
0:27:07 > 0:27:10I've managed to have jelly and some fruit for breakfast,
0:27:10 > 0:27:13which certainly isn't a combination that
0:27:13 > 0:27:15I would normally choose to have for breakfast.
0:27:15 > 0:27:18It's gooey, mushy...
0:27:18 > 0:27:21The food's rather...uninspiring.
0:27:22 > 0:27:24As the week goes on,
0:27:24 > 0:27:27will they find it easier as they get into the swing of it?
0:27:27 > 0:27:31I think they are going to find knowing what foods to eat easier
0:27:31 > 0:27:34because they'll get used to the types of foods
0:27:34 > 0:27:37that they are safe to consume in the first couple of days.
0:27:37 > 0:27:39But aspects of it are just going to get more
0:27:39 > 0:27:41and more difficult as the week goes on.
0:27:41 > 0:27:42They're going to start to feel hungrier,
0:27:42 > 0:27:45they're going to get bored, and also, because without
0:27:45 > 0:27:47fat in their diet, they're going to be eating
0:27:47 > 0:27:49more of things like carbohydrates,
0:27:49 > 0:27:52which could possibly be giving them peaks and troughs in their blood
0:27:52 > 0:27:57glucose levels, giving them surges of hunger and dips in energy levels.
0:27:57 > 0:28:00When I eat loads of carbs, I end up feeling really bloated.
0:28:00 > 0:28:02Will they have that as well?
0:28:02 > 0:28:06There is a group of carbohydrates that we don't break down very well
0:28:06 > 0:28:09and they actually ferment in our large bowel and produce gas,
0:28:09 > 0:28:13and that gives people sort of crampy, painful feelings.
0:28:13 > 0:28:16So, things like beans, pulses, wheat...
0:28:16 > 0:28:18lots of different fruits and vegetables,
0:28:18 > 0:28:22and if they suddenly start eating much more of those types of foods
0:28:22 > 0:28:23than they would normally,
0:28:23 > 0:28:26the chances are they could get some tummy symptoms.
0:28:28 > 0:28:31I haven't felt hungry, but I have felt bloated today,
0:28:31 > 0:28:34which I...haven't enjoyed in the slightest.
0:28:34 > 0:28:38I've got a really, really sore tummy, I'm very bloated.
0:28:38 > 0:28:41I do miss cooking with oil.
0:28:41 > 0:28:43Congee noodle stir-fry.
0:28:43 > 0:28:47I'm starving, so I'll eat it anyway, even if it is disgusting.
0:28:52 > 0:28:54But, of course, most of the time,
0:28:54 > 0:28:57we're free to eat as much fat as we like
0:28:57 > 0:29:00and it's all too easy to overdo it.
0:29:00 > 0:29:04What's not so easy is to burn the fat off again,
0:29:04 > 0:29:07as I know full well myself.
0:29:12 > 0:29:16'Now, as a doctor and as someone who's overweight,
0:29:16 > 0:29:18'I'm a bit obsessed by how we burn fat.
0:29:20 > 0:29:23'Exercise is a key part of it,
0:29:23 > 0:29:28'but there's some exciting research in this area that might offer
0:29:28 > 0:29:31'the less keen amongst us a smarter way to do it.
0:29:33 > 0:29:37'First, I need to find out how much fat my body is burning
0:29:37 > 0:29:40'when I do something simple like walking.'
0:29:41 > 0:29:44This mask is measuring what I breathe in and what
0:29:44 > 0:29:48I breathe out, and it's sending it all to a computer,
0:29:48 > 0:29:50and we'll analyse that later.
0:29:53 > 0:29:57'Now, I've always thought sugar and other carbs
0:29:57 > 0:30:01'are the first source of energy our body draws upon.
0:30:01 > 0:30:06'So I'm not sure if my walk is really burning any fat that all.
0:30:06 > 0:30:10'Sport scientist Dr Jacky Forsyth is crunching
0:30:10 > 0:30:12'the numbers to find out.'
0:30:12 > 0:30:15Well, it shows you've been using quite a lot of fat,
0:30:15 > 0:30:19so approximately 64% of your energy is coming from fat.
0:30:19 > 0:30:22That's your proportion of fat you are using,
0:30:22 > 0:30:24so there was that much fat and the rest you are using
0:30:24 > 0:30:28of carbohydrate and we can convert that into grams for a whole hour.
0:30:28 > 0:30:29Go on, then. Tell me.
0:30:29 > 0:30:34Approximately, you were using about 27 grams of fat, which is
0:30:34 > 0:30:38fairly substantial. You know, you could eat a nice burger with that.
0:30:38 > 0:30:43- That's amazing!- Quite good, isn't it?- That's massive. That is huge.
0:30:43 > 0:30:47'So it's easier to burn fat than I thought.
0:30:47 > 0:30:50'Trouble is, as soon as I stop walking,
0:30:50 > 0:30:55'the fat-burn drops off too, so Jacky's going to show me
0:30:55 > 0:31:00'a trick that'll keep it going - even when I'm not exercising.
0:31:02 > 0:31:06'Lou and Dean are going to demonstrate how to turn your body
0:31:06 > 0:31:10'into an amazing fat-burning machine in three simple steps.'
0:31:10 > 0:31:12That's good. This is excellent.
0:31:12 > 0:31:16'Step one. Exercise hard for just two minutes.'
0:31:16 > 0:31:18Keep it going.
0:31:18 > 0:31:21'Step two. Rest for one minute.
0:31:24 > 0:31:28'Step three. Repeat seven times in total.'
0:31:34 > 0:31:37Keep going. You're doing really well. Keep going.
0:31:37 > 0:31:40'Just 20 minutes later, that's it.
0:31:41 > 0:31:44'The idea is that this pattern of exercise
0:31:44 > 0:31:50'and rest actually makes our body burn more fat for hours afterwards.
0:31:50 > 0:31:55'To see if it worked, we've tested Lou and Dean before and after.'
0:31:57 > 0:32:01Before they started exercising, they were burning this amount of fat and
0:32:01 > 0:32:05then afterwards, they almost double the amount of fat they were burning
0:32:05 > 0:32:10and this was two and a half hours after they'd stopped exercising.
0:32:10 > 0:32:14It even can go on for 24 hours after you've finished exercising,
0:32:14 > 0:32:16so you'll carry on burning that fat.
0:32:16 > 0:32:19That's actually a massive incentive.
0:32:19 > 0:32:24So you keep having the effect of the exercise long after you've stopped?
0:32:24 > 0:32:28Yeah. It's not always twice as much but from the short experiment
0:32:28 > 0:32:30we did, we saw that happen.
0:32:32 > 0:32:36'I'm genuinely amazed it's possible to double the fat we're burning
0:32:36 > 0:32:40'with just 20 minutes of exercise and rest.
0:32:41 > 0:32:46'But could this ever work on someone less fit like me?'
0:32:46 > 0:32:50Do you have to be as fit as Lou and Dean to get same effect?
0:32:50 > 0:32:53No, I think as long as you push yourself proportionally to how
0:32:53 > 0:32:56you feel, then that's fine and what we tried to get Lou
0:32:56 > 0:33:00and Dean to work at was an exercise intensity that they could
0:33:00 > 0:33:03describe as being really hard.
0:33:03 > 0:33:06Now you can get that same benefit if you're not so fit
0:33:06 > 0:33:09but you do have to be prepared to push yourself.
0:33:12 > 0:33:14So whatever your fitness,
0:33:14 > 0:33:18the key is to push yourself to your own limits.
0:33:18 > 0:33:20Even if you're a bit out of shape,
0:33:20 > 0:33:24a regular stride up a steep hill with a quick rest every two minutes
0:33:24 > 0:33:28could increase your fat-burn long after you've finished.
0:33:28 > 0:33:31A lot of gain for not much pain.
0:33:37 > 0:33:41So I've learned it's easier than I thought to burn fat.
0:33:41 > 0:33:47I don't eat a huge amount of fatty food, yet I've still got way
0:33:47 > 0:33:52too much fat in my body, so I want to get to the bottom of why that is.
0:33:52 > 0:33:56What exactly is it that makes us fat?
0:33:56 > 0:34:00To find out, I've come back to medical school to take
0:34:00 > 0:34:03a closer look at fat.
0:34:03 > 0:34:05Right, James. This looks familiar.
0:34:05 > 0:34:08What I'm looking at is some body fat.
0:34:08 > 0:34:11It is. The almost bright yellow parts of this tissue - that's fat.
0:34:11 > 0:34:14- Fat is quite essential to us, actually, isn't it?- Absolutely.
0:34:14 > 0:34:17It cushions the vital organs from injury.
0:34:17 > 0:34:19It makes sitting down comfortable.
0:34:19 > 0:34:22If you were to sit down on a hard plastic chair without fat tissue
0:34:22 > 0:34:25around your bum, it would be very, very painful.
0:34:25 > 0:34:26But most importantly,
0:34:26 > 0:34:29our body fat acts as a store of energy. So as long as
0:34:29 > 0:34:32you've had water and vitamins, you could keep going on the energy
0:34:32 > 0:34:35that's stored inside your body for around 60 days.
0:34:35 > 0:34:38- 60 days with no food? - Up to 60 days for a normal person.
0:34:38 > 0:34:41And how many Mars Bars is that?
0:34:41 > 0:34:44- That's well over 600 Mars Bars. - Crikey!
0:34:47 > 0:34:48If that sounds like a lot,
0:34:48 > 0:34:54anyone who's overweight is carrying even more body fat.
0:34:54 > 0:34:57And to find out why, I'm going
0:34:57 > 0:35:00to look deeper into the secret world of fat.
0:35:02 > 0:35:06- So, James, we're looking at fat under the microscope.- We are.
0:35:06 > 0:35:11This is a slide of human fat cells and within that fat cell,
0:35:11 > 0:35:14- you can see a collection of droplets of oil.- Gosh!
0:35:14 > 0:35:18So each one of these cells is like a little fuel tank of energy.
0:35:18 > 0:35:19Yes, that's quite a good analogy.
0:35:19 > 0:35:22It provides us with energy for periods when you're not eating any food.
0:35:22 > 0:35:26So if you eat too much fat, you will grow fat?
0:35:26 > 0:35:28You certainly can grow fat from eating too much.
0:35:28 > 0:35:31But if you eat too much carbohydrates as well,
0:35:31 > 0:35:33then you will grow fat.
0:35:33 > 0:35:37- So what you're saying, sugar... - Yeah.- Carbohydrates...- Becomes fat.
0:35:37 > 0:35:40- Become fat.- Absolutely. - And they end up looking like that?
0:35:40 > 0:35:41Looking just like that.
0:35:44 > 0:35:47So our own bodies actually make fat.
0:35:47 > 0:35:50If we eat too much of anything,
0:35:50 > 0:35:54like sugar and other carbs, it gets changed into fat
0:35:54 > 0:35:57and stored in cells like these.
0:35:57 > 0:36:01And what's really astonishing is that these fat cells do
0:36:01 > 0:36:04something no other cell in our body can.
0:36:04 > 0:36:07The more we eat, the bigger they grow.
0:36:08 > 0:36:11If you take the average fat cell,
0:36:11 > 0:36:14it can increase in volume by a thousandfold.
0:36:14 > 0:36:18So it can go from being relatively small to being 1,000 times bigger.
0:36:18 > 0:36:21- It's like a party balloon.- Oh!
0:36:21 > 0:36:25So more obese people have bigger cells of fat.
0:36:25 > 0:36:28Absolutely. They generally have larger fat cells.
0:36:28 > 0:36:34So the truth is, simply EATING fat isn't the true reason we get fat.
0:36:34 > 0:36:39The real problem is eating too much, whether that's fat,
0:36:39 > 0:36:41sugar or anything else.
0:36:47 > 0:36:51For our volunteers, the effects of living without fat
0:36:51 > 0:36:53are getting harder to bear by the day.
0:36:53 > 0:36:56All day I've wanted to eat something that I'm not allowed.
0:36:56 > 0:37:01I am definitely hungry. I don't have a lot of energy.
0:37:01 > 0:37:04Today so far, just sleepy and bad-tempered.
0:37:04 > 0:37:09I'm quite sad to know today that turmeric has fat in it.
0:37:09 > 0:37:11I'm hungry when I go to bed, I'm hungry when I get up.
0:37:11 > 0:37:14My tummy is just constantly rumbling.
0:37:14 > 0:37:16I feel like I could eat a scabby horse right now.
0:37:16 > 0:37:20My bowels are not working properly, so I'm a bit, um...
0:37:20 > 0:37:24It's been a long time since I went, just let's say.
0:37:24 > 0:37:28Going fat-free, they are tired, hungry, moody,
0:37:28 > 0:37:32and having some rather unpleasant tummy symptoms.
0:37:32 > 0:37:35I'm beginning to appreciate just why we need fat.
0:37:45 > 0:37:49But exactly which fats are good for us and which are bad?
0:37:49 > 0:37:51Of all the questions about fat, I think
0:37:51 > 0:37:54it's the one that causes most confusion.
0:37:54 > 0:37:56Look at all of these oils and fats.
0:37:56 > 0:38:00There are so many and I want to get to the truth.
0:38:00 > 0:38:04So we've collected some of the bewildering array of fats
0:38:04 > 0:38:07we Brits load into our shopping baskets.
0:38:07 > 0:38:11Some of them come in liquid form as oils.
0:38:11 > 0:38:15Our supermarkets sell nearly 60 million litres of basic
0:38:15 > 0:38:19vegetable oil a year, then there's the solid fats like lard.
0:38:19 > 0:38:22We buy over 15 million kilos of the stuff.
0:38:24 > 0:38:29Why are some fats good and some fats bad?
0:38:29 > 0:38:33Well, as with anything in nutrition, it's never quite as black and white
0:38:33 > 0:38:37as we'd like it to be but we do know that in the UK,
0:38:37 > 0:38:40people tend to have too much saturated fat in their diet.
0:38:40 > 0:38:44So the ones that are at the front that are solid at room temperature
0:38:44 > 0:38:47have a higher proportion of saturates.
0:38:47 > 0:38:51So all these ones at the front, the solid fats,
0:38:51 > 0:38:54are not as good for us as liquid ones?
0:38:54 > 0:38:57Generally speaking, that's the case and there is a link with
0:38:57 > 0:39:01having too much saturated fats and a rise in your blood cholesterol.
0:39:03 > 0:39:06Unhealthy levels of cholesterol are bad news
0:39:06 > 0:39:11because they've been linked to an increased risk of heart disease.
0:39:11 > 0:39:14That's why, over the years, we've seen so much bad press
0:39:14 > 0:39:21about saturated fat, but is unsaturated fat really any better?
0:39:21 > 0:39:25Unsaturated fat almost has the reverse happen,
0:39:25 > 0:39:29whereby it helps to lower your bad cholesterol in your blood
0:39:29 > 0:39:32and actually can be cardioprotective
0:39:32 > 0:39:35and help to protect your heart against heart disease.
0:39:36 > 0:39:41So, used in moderation, some oils can be good for our hearts.
0:39:41 > 0:39:46Extra virgin olive oil is the one most of us know about.
0:39:46 > 0:39:49Rapeseed oil is another popular choice.
0:39:49 > 0:39:52And you can often save a bit of money
0:39:52 > 0:39:55by buying it as a bog-standard vegetable oil.
0:39:55 > 0:39:58Check the label, but it's often rapeseed,
0:39:58 > 0:40:00and costs a lot less.
0:40:00 > 0:40:04People get really confused about what oil they should pick,
0:40:04 > 0:40:08but actually, most of these have the majority of their fats as unsaturates
0:40:08 > 0:40:13which, generally speaking, are better for our heart health and cholesterol.
0:40:14 > 0:40:18So there does seem to be a general rule that unsaturated fat
0:40:18 > 0:40:21is better for us than saturated.
0:40:21 > 0:40:24Broadly speaking, that may be true,
0:40:24 > 0:40:28but recently, the picture has become far more confusing.
0:40:30 > 0:40:34For decades, saturated fat has been thought of as the ultimate baddie,
0:40:34 > 0:40:37the fat we should cut back on.
0:40:37 > 0:40:40But recent headlines have suggested it might not
0:40:40 > 0:40:42be as bad for us as we think.
0:40:45 > 0:40:48Sensational stories like this seem to contradict
0:40:48 > 0:40:52decades of health advice, telling us to avoid saturates.
0:40:52 > 0:40:56And they claim to be based on the latest science.
0:40:57 > 0:40:59No wonder we're baffled.
0:41:02 > 0:41:03So, to get to the truth,
0:41:03 > 0:41:07I've got a rare chance to speak to one of the scientists
0:41:07 > 0:41:11whose work has inspired some of the headlines, Dr Nita Forouhi.
0:41:13 > 0:41:17This hi-tech lab is on the front line in identifying
0:41:17 > 0:41:20the good, the bad and the ugly of the fat world.
0:41:20 > 0:41:22And the results are exciting.
0:41:23 > 0:41:26We are now beginning to understand that, actually,
0:41:26 > 0:41:28saturated fat may not be all the same.
0:41:28 > 0:41:33We tend to think of all saturated fat as one homogenous lump.
0:41:33 > 0:41:38But actually, saturated fats are made up of lots and lots
0:41:38 > 0:41:41of different saturated fatty acids.
0:41:41 > 0:41:45Different foods contain a rich mixture of many types
0:41:45 > 0:41:46of saturated fatty acids,
0:41:46 > 0:41:48and they could have different health effects.
0:41:49 > 0:41:54So different foods contain different saturated fatty acids.
0:41:54 > 0:41:58To try and find out which is good and bad for us,
0:41:58 > 0:42:02Nita's team have done some scientific time travel.
0:42:02 > 0:42:0612 years ago, blood samples were taken from thousands of people
0:42:06 > 0:42:08and frozen.
0:42:08 > 0:42:12Now, the team can identify which fatty acids were in that blood
0:42:12 > 0:42:16and look at the health of the same people today.
0:42:16 > 0:42:17That's quite remarkable.
0:42:17 > 0:42:22So that's like a snapshot of someone 12 years ago, their diet
0:42:22 > 0:42:28and what was going on in their body at that time,
0:42:28 > 0:42:29and we fast-forward to today
0:42:29 > 0:42:32and we see where that person is now, what diseases they have,
0:42:32 > 0:42:35look at the blood samples and see what their links are.
0:42:35 > 0:42:37Yes, you've got it absolutely right.
0:42:39 > 0:42:41What Nita wanted to investigate
0:42:41 > 0:42:45was the link between saturated fatty acids and diabetes.
0:42:47 > 0:42:51It's early days, but her results are a bit of a shock.
0:42:51 > 0:42:57What we found is that there were some individual saturated fatty acids
0:42:57 > 0:43:00that were related with a higher risk of diabetes.
0:43:01 > 0:43:05But there were other fatty acids that were associated
0:43:05 > 0:43:07with a reduced risk of diabetes.
0:43:07 > 0:43:10So, depending on the type of saturated fatty acids
0:43:10 > 0:43:12people had in their blood,
0:43:12 > 0:43:16they are at differing risks of developing diabetes.
0:43:16 > 0:43:20Yes, so the two particular fatty acids that were related
0:43:20 > 0:43:22with a reduced risk of diabetes
0:43:22 > 0:43:25are well known to come from dairy products.
0:43:25 > 0:43:30Nita's study isn't the only one to suggest a link between
0:43:30 > 0:43:34some of the fatty acids in dairy and benefits to our health.
0:43:34 > 0:43:38Other studies have linked one of the fatty acids
0:43:38 > 0:43:40to a lower risk of heart disease.
0:43:40 > 0:43:44Could it be that dairy fat is about to redeem its reputation?
0:43:45 > 0:43:47Well, there's a lot of consistent research
0:43:47 > 0:43:50coming out that dairy products,
0:43:50 > 0:43:52in fact, have beneficial health effects.
0:43:52 > 0:43:56And processed meats have adverse affects for health.
0:43:56 > 0:43:58So the picture isn't black and white.
0:43:58 > 0:44:04Saturated fats don't appear to be all bad or good,
0:44:04 > 0:44:06as the health headlines sometimes claim.
0:44:06 > 0:44:11The latest science suggests that some fatty acids in dairy
0:44:11 > 0:44:14might be good for us, whilst those in processed meats
0:44:14 > 0:44:20like sausage, bacon and pies might be bad for us.
0:44:20 > 0:44:23It's early days for this research.
0:44:23 > 0:44:27Finding promising links isn't the same as proving
0:44:27 > 0:44:29a direct cause and effect.
0:44:29 > 0:44:31And that's the next stage for Nita.
0:44:31 > 0:44:35We cannot prove a causal cause-effect relationship here.
0:44:35 > 0:44:37But that's the next step
0:44:37 > 0:44:40and we certainly have plans to investigate that further.
0:44:44 > 0:44:45This is fascinating.
0:44:45 > 0:44:48But I'm not ready to change my advice
0:44:48 > 0:44:51or do anything radically different myself.
0:44:51 > 0:44:53But a bit of cheese or yoghurt
0:44:53 > 0:44:57might turn out to be good for us in ways we didn't realise.
0:44:59 > 0:45:03There is one sort of fat that really does have star status.
0:45:04 > 0:45:06You've probably heard of it,
0:45:06 > 0:45:09although you might not have realised it was a fat at all -
0:45:09 > 0:45:11omega-3.
0:45:11 > 0:45:14Omega-3 helps build the cells of our body
0:45:14 > 0:45:19and it's a key component of the grey matter of our brains.
0:45:19 > 0:45:23There's evidence it protects against heart disease
0:45:23 > 0:45:25and even possibly stroke and dementia.
0:45:25 > 0:45:30Omega-3 definitely sits in the good fat category.
0:45:33 > 0:45:36One food gives us more of it than anything else.
0:45:36 > 0:45:41And to show you, I'm at London's Billingsgate fish market.
0:45:41 > 0:45:44There's some really amazing fish down here.
0:45:44 > 0:45:48Fish is famously the best source of omega-3,
0:45:48 > 0:45:53and Professor Doug Tocher, a marine biologist from Stirling University,
0:45:53 > 0:45:57is going to show me which fish gives me the biggest helping.
0:45:58 > 0:46:02Explain these test tubes for me then, Doug.
0:46:02 > 0:46:05These test tubes show the amount of oil you get
0:46:05 > 0:46:08in a portion of salmon or sardines,
0:46:08 > 0:46:10compared to tuna and cod.
0:46:10 > 0:46:15So that represents the salmon and that one is the cod.
0:46:15 > 0:46:16That's correct.
0:46:16 > 0:46:20What's really surprising is the salmon looks like
0:46:20 > 0:46:24it's almost got 20 times more oil in it than the cod.
0:46:24 > 0:46:25Yes, that's correct.
0:46:25 > 0:46:28There's a lot more oil in the salmon, but remember, that oil's good oil.
0:46:28 > 0:46:31It contains a high concentration of omega-3
0:46:31 > 0:46:34and delivers a high dose of that to us.
0:46:34 > 0:46:36The cod and tuna are still very good for us,
0:46:36 > 0:46:40but they don't deliver the same high dose that you get with the oily fish.
0:46:43 > 0:46:47So oily fish are the best source of omega-3.
0:46:47 > 0:46:50This is like an omega-3 corridor. So we've got...
0:46:50 > 0:46:53Mackerel, this side, salmon, this side.
0:46:53 > 0:46:57Just one portion per week gives us all we need.
0:46:59 > 0:47:02So why do some fish have more oil in them than others?
0:47:02 > 0:47:08It's just because some fish store their fat in their livers, like cod,
0:47:08 > 0:47:11- hence we get cod-liver oil that's rich in omega-3.- Oh, yeah!
0:47:11 > 0:47:14And other fish store their fat within the flesh,
0:47:14 > 0:47:16and they're the so-called oily fish.
0:47:16 > 0:47:20So when we eat these fish, we get the biggest those of omega-3.
0:47:23 > 0:47:26But what if you don't like fish?
0:47:26 > 0:47:30Well, what's really exciting is that the food of the future
0:47:30 > 0:47:33could soon be packed with omega-3,
0:47:33 > 0:47:35thanks to some ground-breaking new science.
0:47:41 > 0:47:42And, amazingly,
0:47:42 > 0:47:46the place we'll get all this extra healthy fat from is water.
0:47:46 > 0:47:49We've got some live seaweed down here, look.
0:47:49 > 0:47:50That's a pool there, isn't there?
0:47:50 > 0:47:53'Dr Carol Llewellyn from Swansea University
0:47:53 > 0:47:58'is an expert in marine algae or seaweed.
0:47:58 > 0:48:00'We're all familiar with it on the beach,
0:48:00 > 0:48:03'but Carol's more interested in algae so tiny,
0:48:03 > 0:48:05'we can't even see them.
0:48:05 > 0:48:07'They're in the seawater itself.'
0:48:07 > 0:48:11And here it comes, right on cue, the sea!
0:48:11 > 0:48:15So, all this is full of algae that we actually can't see?
0:48:15 > 0:48:17Yes, they're microscopic living cells,
0:48:17 > 0:48:22- and these actually do contain high levels of omega-3 oil.- Wow, OK.
0:48:22 > 0:48:26- Shall we collect some and have a look at some under the microscope?- Yep.
0:48:26 > 0:48:31This water looks crystal clear, but it contains tiny,
0:48:31 > 0:48:35invisible algae with a hidden bounty of omega-3.
0:48:37 > 0:48:42Magnified hundreds of times, a whole secret world of tiny algae.
0:48:44 > 0:48:46So there they are.
0:48:46 > 0:48:50And they're all different shapes and sizes and colours.
0:48:50 > 0:48:52We can see three or four different varieties,
0:48:52 > 0:48:56but actually, in the ocean, there are thousands of different microalgae.
0:48:59 > 0:49:03They look really, really pretty.
0:49:03 > 0:49:07Like pieces of jewellery. They're stunning, actually.
0:49:10 > 0:49:16Amazingly, minuscule algae cells can contain up to 50% oil,
0:49:16 > 0:49:19so they're a massive potential source of omega-3.
0:49:19 > 0:49:22Trouble is it could take tonnes of seawater
0:49:22 > 0:49:25to end up with just a few spoonfuls of oil.
0:49:25 > 0:49:28So this is the greenhouse. Come on in!
0:49:28 > 0:49:33'So Carol is trying to grow her own, on an industrial scale.'
0:49:33 > 0:49:37This looks like some giant sunbed.
0:49:37 > 0:49:39Well, I suppose it is, for the algae that are growing in it,
0:49:39 > 0:49:44because the algae actually need light to grow and multiply.
0:49:46 > 0:49:47Inside these pipes,
0:49:47 > 0:49:51the algae are concentrated up to a million times more
0:49:51 > 0:49:55than in the seawater, and this makes it possible
0:49:55 > 0:49:59to get our hands on their precious cargo of omega-3.
0:50:00 > 0:50:03We can then take the algae out and dry it,
0:50:03 > 0:50:08and I actually have a sample here of the dried biomass.
0:50:08 > 0:50:12So that is dry microalgae?
0:50:12 > 0:50:15Absolutely. You've got it in one.
0:50:15 > 0:50:18Suddenly, we've got microalgae that we can see.
0:50:18 > 0:50:21Yes, and you could actually eat this as it is
0:50:21 > 0:50:26and it's very rich in nutrients and in the omega oils.
0:50:26 > 0:50:27Always up for a go.
0:50:29 > 0:50:31It's really salty!
0:50:31 > 0:50:35It's just like taking a concentrated tablespoon of salt!
0:50:35 > 0:50:39We can go one step further and extract the oils from that
0:50:39 > 0:50:43to actually produce a pure algal omega oil.
0:50:43 > 0:50:45So it's cutting out the middleman...
0:50:45 > 0:50:48- Or the middle fish! - Yes, you could say that.
0:50:48 > 0:50:51You can buy algal products in health food shops, currently,
0:50:51 > 0:50:53and I'm sure that, as years go by,
0:50:53 > 0:50:56it will become a more mainstream source of food.
0:50:56 > 0:50:58So it's a future food?
0:50:58 > 0:51:02It's a food for the future, and it's also very sustainable.
0:51:02 > 0:51:07But eating this stuff ourselves isn't the big idea.
0:51:07 > 0:51:10What could really transform our food in the future
0:51:10 > 0:51:12is feeding it to animals.
0:51:16 > 0:51:19On this farm in Shropshire, Professor Liam Sinclair
0:51:19 > 0:51:22has tried feeding microalgae to sheep.
0:51:22 > 0:51:25And now he's about to start giving it to cattle.
0:51:25 > 0:51:30The aim is to produce meat and milk that's rich in omega-3.
0:51:32 > 0:51:37We're looking at feeding the microalgae to dairy cows
0:51:37 > 0:51:40and to beef animals and trying to see if we can get it into the milk
0:51:40 > 0:51:44and then, subsequently, into products such as cheese.
0:51:46 > 0:51:49If this works, Liam predicts that we could get
0:51:49 > 0:51:54about 15% of our omega-3 from dairy products.
0:51:54 > 0:51:59Our aim is that people can increase their intake of omega-3
0:51:59 > 0:52:01without necessarily having to eat fish
0:52:01 > 0:52:03because a lot of people don't like fish
0:52:03 > 0:52:05and fish sales are decreasing
0:52:05 > 0:52:08and the overall objective is to improve people's health
0:52:08 > 0:52:12without them necessarily having to alter their diet.
0:52:15 > 0:52:19So we may be looking at a future where we can get our omega-3
0:52:19 > 0:52:22from a whole host of everyday foods,
0:52:22 > 0:52:25from beef and lamb, to milk and cheese.
0:52:27 > 0:52:30Right now, we haven't quite cracked how to make it
0:52:30 > 0:52:33on a big enough scale to be commercially viable.
0:52:33 > 0:52:39So in the meantime, it might be worthwhile learning to like fish.
0:52:43 > 0:52:46After a whole week of going fat-free,
0:52:46 > 0:52:48our volunteers are back.
0:52:48 > 0:52:50Welcome back, everyone
0:52:50 > 0:52:53and first of all, a huge well done.
0:52:53 > 0:52:54What was it like?
0:52:54 > 0:52:57It has been a really difficult journey,
0:52:57 > 0:52:59really difficult to make food taste nice.
0:52:59 > 0:53:03I found it really hard, mainly because a lack of energy.
0:53:03 > 0:53:06I ate plenty, but I planned everything,
0:53:06 > 0:53:08I had to plan everything I had to eat.
0:53:08 > 0:53:10Glad to hear some people planned, but I didn't,
0:53:10 > 0:53:11and that was really tough.
0:53:11 > 0:53:16First morning, I had salad with fat-free yoghurt.
0:53:16 > 0:53:18Strawberry flavoured.
0:53:18 > 0:53:20LAUGHTER
0:53:20 > 0:53:23You put strawberry yoghurt on your salad?
0:53:23 > 0:53:27I wanted a bit of taste so the strawberry...
0:53:27 > 0:53:31- I didn't know what else to eat. - How was it?- Horrible.
0:53:31 > 0:53:33So you haven't discovered something, then?
0:53:33 > 0:53:35No, not at all.
0:53:35 > 0:53:37How do you feel about stopping today?
0:53:37 > 0:53:40ALL: Yay!
0:53:40 > 0:53:42None of you were tempted to carry it on?
0:53:42 > 0:53:43ALL: No!
0:53:43 > 0:53:45That's all right. Wouldn't recommend it, anyway.
0:53:45 > 0:53:48Of course, this was a really extreme thing to ask you to do,
0:53:48 > 0:53:50to completely take fat out of your diet
0:53:50 > 0:53:52and it's not something, in general practice,
0:53:52 > 0:53:55we would advise people to do to try and lose weight, for example.
0:53:55 > 0:53:57It's not a healthy way to do that.
0:53:57 > 0:53:58So I'm glad none of you want to carry it on
0:53:58 > 0:54:00because we wouldn't recommend it.
0:54:02 > 0:54:07In their seven days without fat, our volunteers felt hungry,
0:54:07 > 0:54:10bloated, constipated, and lacking energy.
0:54:10 > 0:54:14To measure some of the effects the week has had,
0:54:14 > 0:54:17Professor Jane Ogden is running some tests.
0:54:17 > 0:54:21Tell me the colour of the ink and not the word, OK? And go.
0:54:21 > 0:54:24Blue, red, green, red, blue, blue, green, red...
0:54:24 > 0:54:29One dramatic finding is how their levels of tiredness changed.
0:54:29 > 0:54:33Pretty much everybody felt more fatigued and tired
0:54:33 > 0:54:35and everybody had much less energy.
0:54:35 > 0:54:40Jane also tested to see if cutting out fat had created
0:54:40 > 0:54:43unconscious desires and our volunteers' brains.
0:54:43 > 0:54:48Using an eye tracking device and pictures of different foods
0:54:48 > 0:54:54we can see what they were most drawn to before and after the week.
0:54:54 > 0:54:57What we find at the beginning of the week is that really,
0:54:57 > 0:55:00they just look all over the place and you can see the results are mixed.
0:55:00 > 0:55:03They are looking a bit at the salad, a bit at the cheesecake,
0:55:03 > 0:55:04they're looking a bit at the bread,
0:55:04 > 0:55:06but they are looking all over the place.
0:55:06 > 0:55:10This is a typical response from the beginning of the week.
0:55:10 > 0:55:13The green colour shows a low intensity of eye contact
0:55:13 > 0:55:17pretty evenly spread across the foods.
0:55:17 > 0:55:21Now let's look at the same volunteers' responses
0:55:21 > 0:55:23at the end of the week.
0:55:23 > 0:55:25After a week of no fat,
0:55:25 > 0:55:28the chocolate brownie gets much more eye contact,
0:55:28 > 0:55:31as does the burger and chips.
0:55:31 > 0:55:36The fruit salad gets less eye contact after the fat-free week.
0:55:36 > 0:55:41And look how this volunteer focuses on the vegetable plate.
0:55:41 > 0:55:44Even on the vegetables, but not really on the vegetables,
0:55:44 > 0:55:45on the dip.
0:55:45 > 0:55:47I think that one is fantastic.
0:55:47 > 0:55:50They have bypassed the cucumbers and carrots
0:55:50 > 0:55:54- and gone for a bull's-eye straight onto the dip.- Yes.
0:55:54 > 0:55:57- So whose is that one then? - That is Rashmi's.
0:55:57 > 0:56:00I was thinking about the dip cos I just love avocado.
0:56:00 > 0:56:03I was really craving. That's why.
0:56:03 > 0:56:07What's nice about the eye tracker, I think, is that even if you're not consciously aware
0:56:07 > 0:56:10that that's what you're drawn to your eyes are still going there
0:56:10 > 0:56:11and that's what this can pick up.
0:56:13 > 0:56:19The zero fat challenge has altered the thoughts, behaviour and emotions
0:56:19 > 0:56:21of all our volunteers.
0:56:21 > 0:56:25Larger scientific studies have shown that in the long-term,
0:56:25 > 0:56:29extreme fat reduction may affect our mood
0:56:29 > 0:56:32and can even increase anger and hostility.
0:56:32 > 0:56:37For our volunteers, zero fat week is over.
0:56:37 > 0:56:42So we've laid on a healthy spread that should satisfy their cravings.
0:56:42 > 0:56:43This is nice.
0:56:43 > 0:56:45They obviously look really pleased.
0:56:45 > 0:56:49Yes, I think it just shows what a massive role fat plays
0:56:49 > 0:56:51in our everyday eating.
0:56:51 > 0:56:55They've been so restricted with the amounts and types of foods
0:56:55 > 0:56:59that they can eat when trying to follow an eating plan free of fat.
0:56:59 > 0:57:01Fat is one of our three main nutrients
0:57:01 > 0:57:03and if you suddenly take that out,
0:57:03 > 0:57:06you have to eat a lot more of the other nutrients,
0:57:06 > 0:57:07which can have symptoms in itself.
0:57:07 > 0:57:10And also, fat gets a really bad rep,
0:57:10 > 0:57:13but it plays an important role in our health.
0:57:13 > 0:57:17And as these guys have noted you get symptoms if you don't eat it.
0:57:17 > 0:57:19There's so much choice...
0:57:19 > 0:57:25These foods are good ways to eat the right kinds of fats.
0:57:25 > 0:57:30Unsaturated olive oil, avocados, oily fish, nuts and seeds,
0:57:30 > 0:57:33together with a moderate amount of dairy,
0:57:33 > 0:57:37lean meat and plenty of veg, we won't go far wrong.
0:57:37 > 0:57:43As a doctor, I know that fat belongs in our diet and in our bodies.
0:57:43 > 0:57:47But it is really difficult to shake off that sense
0:57:47 > 0:57:49of fat somehow being the enemy.
0:57:49 > 0:57:54But these guys have shown that fat really does play an important role
0:57:54 > 0:57:56in the food that we eat
0:57:56 > 0:58:01and that life without it is unpleasant and difficult.
0:58:01 > 0:58:04The idea that fat is bad is wrong.
0:58:04 > 0:58:07We've just got to make sure that we eat the right amounts
0:58:07 > 0:58:09and the right kinds.
0:58:09 > 0:58:13Next time, the truth about Britain's top-selling
0:58:13 > 0:58:15over-the-counter medicines.
0:58:15 > 0:58:17You don't often visualise what's happening to medicines
0:58:17 > 0:58:19once you put them in your body.
0:58:19 > 0:58:22From painkillers to cough syrups, are these common cures
0:58:22 > 0:58:26all they're cracked up to be?
0:58:26 > 0:58:28This leg now feels like it is on fire.