Today in Britain, 11 million of us are on a diet.
Yet, 80% of us fail.
So how can we make our diets work?
Well, scientists believe they may have the answer.
And it's all about a new approach to dieting,
a personalised diet for each of us.
One that's based on our genes, our hormones and our psychology.
For the first time, we're going to put this new science to the test
in a ground-breaking national experiment.
We're taking 75 overweight volunteers
and putting them on diets
which are tailored to their individual bodies and brains.
The experiment is being carried out
by some of Britain's leading obesity scientists,
specialists in areas like dieting and nutrition,
from Oxford and Cambridge Universities.
To be honest, the experiment had never actually been done before.
The scientists will put our volunteers through a series of tests
to find out what causes them to eat too much.
Oh, look! See? You are burning fat like nobody's business.
The experts will then allocate them to the diets which best suit them.
Diets are about habits.
There's never been a study that says
that people can will themselves to lose weight.
The more you want the item of food, squeeze harder.
For three months, each volunteer will be on a personalised diet.
That is five pounds of fat.
Can science succeed, where other diets have failed?
And if this personalised approach to dieting works,
it could transform the way we all lose weight.
I'm Chris van Tulleken.
I'm a medical doctor and a research scientist.
And I'm Professor Tanya Byron, a clinical psychologist.
I often work with people with eating disorders.
People overeat for different reasons.
And the latest science shows
that it may be due to our individual make-up.
So this series is about discovering the individual causes for overeating.
And the answer could lead each of us to the perfect diet.
Our experiment began by putting a call across the country
for overweight recruits.
We invited hundreds of them to a series of assessment days
in Glasgow,
Manchester
and London.
I've been on a diet all my adult life.
I've yo-yo dieted since I was 15 and I'm 53 now.
I'm on it for about a week, a week and a half,
a month or two, max.
And then I just...fall off.
Our obesity scientists put the applicants
through a range of medical tests,
to try to find out why they eat too much.
We're building up profiles of volunteers
by testing their genes, their hormones and their psychology.
And all of the information we gather
will be used to find out what kind of eaters they really are.
At the end of this assessment, our experts chose 75 volunteers
and allocated them to three different eating groups.
Each group will be put on a different diet,
designed to address the causes of their overeating.
But, before that, the scientists want to test the groups.
They're going to do all this here at Liverpool Hope University.
We're calling it the Diet Lab.
Yeah, welcome. How are you doing? Really nice to meet you.
Hi, I'm Claudia. Nice to meet you. How was your trip?
Throughout the three months of this ambitious experiment,
our 75 volunteers will regularly be returning here to be tested.
In this first programme,
they're starting with an intensive, five-day analysis.
Thank you so much for coming, everyone,
and welcome to our rather fabulous Diet Lab.
And we are joined by the foremost experts in Britain
in the science of nutrition and diet.
It's an amazing team.
There is a massive breadth of knowledge.
As you remember, during the selection process,
we did a number of tests on you.
What we want to do now for the next couple of days
is do some more investigations.
And then we're going to pull all that data together,
then reveal to you what, we believe, is exactly the right diet for you.
But the good news is that doesn't start until tomorrow.
So, tonight, we have laid on a fabulous evening.
A kind of last supper, as it were.
We want you to just relax and chill out and get to know each other.
Thank you. Well done.
It's time for our volunteers' first meal together.
They're invited to our Diet Lab's great hall.
But their diets haven't started yet.
So, tonight, they're free to eat and drink as much as they like.
Would you like more wine, sir? Yes, please. Thank you.
It's my pleasure.
On the menu is sushi,
a never-ending supply, delivered by conveyor belt.
And there's a good reason we're laying on this dinner.
Well, I think they are having a brilliant time.
But, of course, what we haven't told our volunteers
is the experiments in the Diet Lab have already begun.
Our sushi supper isn't just a welcome dinner.
Our experts are interested to see
if this experiment can illustrate
the first of our three categories of eater.
Now, this is the nerve centre, where the experts hang out.
It's hard to think of many rooms in the world
with this amount of combined expertise
on the science of diet and nutrition.
Unknown to our volunteers,
our experts are secretly watching them eat,
using hidden cameras.
This is, obviously, an amazing setup.
But why aren't you just out there with clipboards,
in amongst them, observing it?
Well, here's the key thing.
The most interesting thing here is how unselfconscious
they are at eating.
They are eating naturally, they are eating lots of the food.
If we were out there with clipboards and cameras in their faces,
I don't think they would do the same thing.
Crucially, the scientists haven't yet told any of the volunteers
which group they're in.
Before they do that, they want to check that the groups overeat
for the reasons their assessments suggested.
The sushi supper is testing the first group.
We're calling them the feasters.
At our assessment days, Professor Fiona Gribble and her team
measured everyone's gut hormone levels.
Those with the smallest rise in hormones when they ate
were selected for the feasters' group.
For most of us, when food arrives in our intestines,
hormones are released.
These hormones are chemical signals.
They travel through the blood and reach the brain.
This is how they tell us when we've had enough food
and should stop eating.
But people in our feasters' group produce less of these gut hormones.
In particular, one called GLP-1.
It means the signal that tells them to stop eating is weaker.
Fiona predicts that, because of the low levels of their gut hormone,
once the feasters start eating, they'll find it hard to stop.
Quick! Get in there before someone else does!
To prove her theory, she's measuring exactly how much everyone's eating.
Each bowl contains around 150 calories.
And the waiters are collecting every one that's finished.
So, down here is the room where the data is being compiled.
It's not the kind of data you normally think of
in a science experiment.
Have a look at this...
This is where the plates are being counted.
Our waiters are placing the empty plates
next to the picture of the relevant volunteer,
so we know how much they've eaten.
For a normal meal,
six of these bowls should be plenty for a man
and five should be plenty for a woman.
The volunteers have been eating for an hour
and the plates are stacking up.
Fiona's prediction for the feasters seems to be coming true.
There are a few who are already standing out
as eating much more than everyone else.
This chap Peter is one of them.
He's consumed many more plates than many of the others.
What's he at so far?
He's had about 12 plates already
and more than half of his daily calories already,
just in the first half of this meal.
So, 12 plates of 150 calories each. So, he's way over 1,500 calories.
Almost at 2,000 calories.
And that's... You know, a man only needs 2,500 in a day.
Peter is a feaster.
And other members of the feasters' group are eating similarly.
I've been watching Heidi,
who has also managed to power her way through about 12 dishes so far.
And she's been drinking, as well.
So, she'll have got quite a lot of extra calories from the wine.
Next to Heidi we have Alistair.
He's so far got through 17.
17, really?!
So he is now well over
the amount that a kind of average man would need in a whole day.
That's right. In a whole day.
When everyone's finished, the plates are collected and counted.
With the non-feasters, no volunteers ate more than 14 plates.
But, with the feasters, nine volunteers ate more than 14 plates.
And one of the feasters ate 19 plates.
For Fiona Gribble, it shows the strong link
between a lack of hormones in the gut
and not being able to stop eating.
You predicted these people would be in this category
of people who couldn't stop eating.
To be honest, the experiment had never actually been done before.
These gut hormones are a fairly new field.
People are very interested in them
because they do know they're a very strong influence on appetite.
And I'm absolutely fascinated to see our predictions
playing out in a real-life situation.
My name is Peter Anthony Loizou.
I'm 50 years old.
I'm a retired police officer from Manchester.
When I eat a normal portion,
when everyone else is happy, I want more.
I don't seem to get full.
I'm at that breaking point now. I need help.
I realise how upsetting it is, particularly my son.
Breaks his heart when he sees me.
He says, "You're going to have a heart attack,
"and I'm worried that you're going to die."
We're going for it.
No more excuses. No excuses.
He gets upset, saying, you know, "I don't want you to die, Dad."
You know, he's 14 and he's got, like, the world ahead of him
and I want to see him grow up.
I'm not looking forward to this.
I'd say you'd lose some this week.
Friday morning, he weighs me.
Oh, God...
19st 4.7lb.
No! Yeah.
And he puts it on a chart in his bedroom.
And, like, if I haven't lost, he says, "You promised me."
Plus six pound.
Oh, you're joking?
No, I'm not happy, Dad.
Not good, is it?
The wife will say, "If I'm with you 24 hours a day..."
If I was with you 24-7...
"..you'll lose weight." ..you'd be slim
I suppose I'm in denial a lot of the time.
And you kid yourself. I know. You're in denial.
And I'm just letting everyone down, including myself.
And you're only letting yourself down, really, at the end of the day.
So, our non-stop sushi experiment
has confirmed the first of the three groups in our experiment -
the feasters.
Now, when these guys start eating, they find it really hard to stop.
So, what our experts have to do now is design a diet
that will specifically combat this problem.
And you can find out your own eating type
by using our online diet questionnaire.
Visit...
..to discover what the best way might be for you to lose weight.
After a night on the sushi, our volunteers are waking up
to their first morning at the Diet Lab.
Even though we've tested our first group, the feasters,
none of the volunteers yet knows
which of the three dieting groups they are in.
Today, the scientists want to test the next type of eater.
20 of them are about to undergo a psychological test.
It's one they're unlikely to forget.
This morning, our experts are going to meet a new group of volunteers -
those who seem to be having problems with their eating
due to psychological issues.
During the assessment days,
all applicants were asked to fill in
detailed psychological questionnaires.
Behavioural scientist Professor Paul Aveyard
used these questionnaires to select a group of individuals
who seemed to turn to food when anxious, depressed or stressed.
We're calling them the emotional eaters.
Back at the Diet Lab,
Paul wants to test the power of this emotional eating.
He has taken ten people, who are from the emotional eaters' group,
and ten people who aren't.
And he's going to put both groups through an experiment
to compare how much each eats after a stressful experience.
OK, today's experiment is about the way the body affects the mind.
And we're going to ask you to do something today
that many of you won't have done since you were teenagers.
And that is to take a driving test.
Good Lord!
Oh, my goodness me!
I was 17 when I sat my driving test,
which, I know, was only last year, but...
..last year seems like quite a while away.
And it's got a lot tougher since then.
And these are your examiners.
The aim of our driving test
has nothing to do with how good our volunteers are behind the wheel.
Its sole purpose is to raise their stress levels.
I feel a bit sorry for them.
Goodbye.
Rather you than me.
Do you want to put your seatbelt on before we actually start? Oh, sorry!
Sorry...
Enjoy!
To make sure everyone is stressed,
Paul has briefed the examiners to speak only when necessary.
No compliments, no chit-chat,
just stern silence.
It's a technique that, in psychological tests,
has been shown to induce high levels of stress.
He's also asked them to fail everybody.
Constantly telling a person they are failing makes them more anxious.
A serious fault committed there.
You've already committed two driver faults.
You went for a gear that you didn't need. I didn't.
Didn't I go to third and then to second? No.
And the more anxious they are, the more their stress levels rocket.
Sorry. Sorry.
Stress makes them drive even worse.
LOUD THUMP
Oh, that's gone right up the driveway.
It's a vicious, stressful cycle.
Are you happy with that?
Well, I bumped the kerb a little.
You're actually on the kerb. Oh, right...
Do you know how I feel at the minute?
I just want to cry and go back and pack my stuff and go.
Eh?
Meanwhile, back at the Diet Lab,
Paul is preparing identical lunches for the two groups.
All the food on the tables is carefully weighed.
This is an experiment which is really looking to see
whether all that stress we put our volunteers through
is going to affect their eating. OK.
And we've got our two groups.
We've got people who eat in response to stress,
and our questionnaires told us that.
And then we've got the people who don't respond in that way.
And we can be able to compare the groups
and kind of see how much they eat.
I could feel my heart going ten to the dozen
and my stomach turning.
That was horrendous! It was horrendous?
Absolutely horrendous!
Rate your stress out of ten.
12. 12 out of ten?
OK. OK. Well done. Thanks for doing it.
Let's go in and sort of sit down and debrief and chill out.
Oh, here we go...
When people are stressed, they produce a hormone called cortisol.
And we can measure cortisol levels with a simple saliva test.
Enjoy. Yeah...
It'll tell us how far everyone's stress levels have risen.
Oooh, nice tongue pierce.
Ready? No talking now.
That's it. Hold it in your cheek.
At least it's not a stool sample!
Now, let's see how much they eat after their stressful experience.
We've split up the emotional eaters and the non-emotional eaters.
Once again, neither group knows we're watching what they eat.
When they've finished, the plates of food are secretly weighed again,
to see exactly how much each group has eaten.
And back in the control centre, Paul analyses all the results.
OK, so, Paul, what are we seeing here?
So, over here, we've got our emotional eaters.
And here, we've got our non-emotional eaters.
And what we're looking at
is how much food they eat in response to stress.
And we know they were stressed
because their cortisol response went up.
So everybody got stressed? Everybody got stressed.
So how much did each group eat?
Now, here, I'm just looking up there and the emotional eaters
have eaten significantly more sweet and sugary snacks.
Yeah, four times as much chocolate, biscuits and crisps.
In a stress response, our brains are primed to seek out reward. Right.
And foods that are high in fat and high in sugar
are particularly rewarding foods.
So, why doesn't everybody do the same thing, then?
Why aren't the non-emotional eaters doing this if they're as stressed?
Because people respond in all sorts of different ways
and seek reward, for example, through drinking
or through other behaviours.
So, more healthy ways, like exercise, running, that kind of stuff?
Yep, that's a great way of dealing with stress.
Here we're seeing the emotional eaters overeating.
Yeah. And that puts them at risk of gaining weight.
So, we've now identified very clearly our emotional eating group.
They use food as a way of managing emotion. Yeah.
How does this impact on the diet that we designed for them?
Well, what we've got to help them do
is find new ways of managing their emotions.
And not use food as a way of dealing with stress or feeling bad.
Exactly.
My name's Susan, Susan Arthur, and I'm from Edinburgh.
Hey, you, pussycat...
I eat a lot more when I'm
stressed out and...
..when I'm anxious.
I just... I comfort eat.
My relationship broke up.
I was sitting in the house in the evening.
I was lonely.
Biscuits were shouting my name, crisps were shouting my name.
And I just sat and I comfort ate.
And then, that then became a habit.
So then, as I was putting on the weight,
it was easy to put it on, but a lot harder to take it off.
I want to be able to go out and socialise and have a life.
Maybe meet somebody,
because, I mean, I have been on my own for quite a while now.
So far at the Diet Lab, our scientists have tested and confirmed
two of the three dieting groups...
..the feasters...
..and the emotional eaters.
I'm sorry.
Yet, none of our volunteers knows which group they are in.
Before the scientists reveal this,
they want to test the third and final group.
We're calling them the constant cravers.
It's all based on the latest genetic research into eating behaviour.
Within the human body,
scientists have discovered a number of key genes
which, if you have them, can make you constantly want to eat.
For most people, when our fat stores are at a sufficient level,
signals are sent to our brains to tell us that we don't need to eat.
But scientists have discovered that constant cravers have genes
which disrupt the way these signals are received.
They trick their brains
into thinking the fat stores continually need replenishing.
The result? They're hungry the whole time.
During the assessment days geneticist Dr Giles Yeo
identified 25 volunteers,
who had particularly high numbers of these obesity genes.
They make up this third group, the constant cravers.
Today, Giles is testing the strength of the constant cravers' desire
to continuously eat.
His experiment starts
by feeding all our volunteers a hearty lunch to fill them up.
Two hours later, everyone is invited back to the Diet Lab's great hall.
All right, hello, everybody.
Today we're going to conduct an experiment
called the grip force test.
Grip force test.
So, our waiters are going to show you a food item
every minute for five seconds.
And the whole point of this exercise
is to test your responses to different types of food.
Now, in front of you, we have a grip force meter.
OK? And what we want you to do
is to squeeze every time you see the item of food.
But the key thing here is, the more you want the item of food,
I want you to squeeze harder.
OK? So, everyone, ready. I want you to have a go, OK?
One,
two,
three...
Hold it!
The grip force meter registers how hard each person squeezes.
Fantastic!
The number it gives
represents how much that person desires the food in front of them.
And it's calibrated to take account of everyone's different strengths.
The more you want the item of food, I want you to squeeze harder.
Giles wants to compare the squeezing by the constant cravers
to that of the other two groups.
Why are we using the grip meter and not just a questionnaire?
Well, because the problem is, if you have a questionnaire,
you have a score, you can put one or two or eight.
Whereas, the thing about the grip meter is,
because it's so difficult to actually know
how hard you're gripping,
we hope that it will give you a more natural response.
So, the grip meter is almost, like, short-cutting the brain
and just connecting your desire to your hand.
Absolutely. You don't have to use higher brain activity.
Crisps! You can squeeze and it's good.
That kind of gut feeling if I want crisps. Yeah, exactly. Definitely.
I do want some crisps.
I love crisps.
Despite having eaten lunch just two hours earlier,
some volunteers are still very keen on the food on offer.
Oh, I could just break a bit of that off and eat it.
Mmmm!
My hand went down and I couldn't let go.
It made me want to just reach in there and grab a little bit.
Crisps and popcorn are two of my weaknesses...
..of my many lists of weaknesses.
I love anything that's got pastry in it.
Amongst the foods Giles has chosen
are eight that are particularly high in sugar or fat.
Classic snacking foods.
Yeah.
Definitely.
I love a good cupcake.
With one last, big, squeeze, the experiment is over.
And remarkably, true to Giles's predictions,
the constant cravers seem hungrier than the other groups.
And they prefer the foods high in sugar and fat.
What have you discovered?
Well, we've got a result.
So, we've got the results from all eight foods now
and it does appear that the constant cravers
are pulling harder for five of the eight foods.
Really? Compared to everyone else, yeah.
Really? Yeah, absolutely.
In spite of the fact that it's in the middle of the day,
two hours after lunch.
Five out of eight is... That's a good result.
It's a good result.
Presumably, then, this is going to give us
a way in to designing a diet,
a dieting strategy, for people with these genes?
Absolutely.
The thing is,
how do you fight that higher drive to eat throughout the day?
And that's what we have to tackle
if we're going to have an effective diet.
Eden! Yes, Mummy?
Sweetheart, can you come and help, please? Just quickly...
Just come and dry up.
My name's Sharon Ferreira.
I'm approaching 46.
I live in north London.
Food, for me, is everywhere.
I think about it all the time.
It's almost like a secret partner that nobody knows about,
that nobody sees me with, but I really enjoy.
She looks like a supermodel to me because she's lovely.
And people even ask if she's a supermodel.
Physically, I've never looked at myself and thought,
that looks fantastic, you look great.
I just don't feel like that.
I try to tell myself that I'm OK, but I'm just lying.
For me, it's just...
It's horrible.
I'd like to be like you when I grow up.
Nice and slim.
Oh, you are nice and slim!
Thanks, darling.
I love you.
Love you, too.
Health is a definite major part of this for me.
I want to live for as long as I can,
because I don't want to leave my daughter behind.
She's far too young.
Nothing is impossible.
That's what my teacher says.
Good!
And I need to adopt that.
Using the latest science, our experts have confirmed
that their three groups match the eating behaviour they anticipated.
But, so far, none of our volunteers knows which group they belong to,
or which diet they'll be put on.
Now that's all about to change.
It's time to reveal which group they're in
and why the scientists think they overeat.
The first group of people, once they start eating,
they tend not to stop.
And we think that's because
your gut isn't releasing enough of the hormone
that tells your brain when you're full.
We're calling you the feasters. I hope you don't mind.
Alistair...
Whooh!
APPLAUSE
Fay, Heidi, Peter...
APPLAUSE
Feast.
So, that's exactly what I do.
At least I know now that my gut hormone isn't working properly
and that maybe we can address this and work on it from there.
The second group of people is a group who turn to food
at times when they're emotional or stressed.
And we're calling you the emotional eaters.
CHEERING
Alison Vaughan.
Chantelle.
Diane.
Derek.
Whooh!
Oh, I love Derek.
Well, it's going to give me coping mechanisms
to sort of try and combat, when I am feeling emotional, not to eat.
It's like a big step for everyone, it's a big deal.
It could be life-changing.
After the driving test yesterday,
I definitely knew I was in the emotional group!
Susan.
Such a great lady.
Yay, Susan! No surprise, eh?
The third group is a group of people who have a pattern of eating
where they are hungry throughout the day and they eat between meals.
That's because you have a high number of the genes
that predispose to weight gain and obesity.
And we're going to call you the constant cravers.
John.
Morris.
Morgan.
Hi. What's up, dude? Here we go. Fantastic.
I've always maintained that it was in my genes
and nobody would listen to me.
And I now know that it is.
So, I've got my father's family to blame for it.
Thanks, Dad!
Nicola. Patricia. Darren.
Tracey and Hazel.
Yeah!
OK. So, here it is. This is the beginning of a new chapter,
a chapter that we really hope will make a massive difference
for the rest of your lives.
Good luck, everybody.
Now, finally, we can allocate our volunteers
to the personalised diets, which address their overeating,
the right diet for them.
Weight loss studies show that, if you're trying to diet,
then losing five percent of your body weight
is a tough target to reach.
Our experts want to discover whether the volunteers can hit five percent
using this new, personalised approach.
Nutrition scientist Professor Susan Jebb
has chosen the right diet for each group.
This is just to give you a little insight
into what your shopping baskets are going to look like
next time you go to the supermarket.
The first group are the feasters.
They have low levels of a gut hormone,
which tells them when to stop eating.
So, what they need is a diet that makes them feel full
for as long as possible.
Susan is putting them on something called the high-protein and low-GI,
or glycaemic index, diet.
OK. So, you guys, the feasters,
you find it difficult to stop eating.
So, we're going to choose foods
which we know boost your gut hormone signals
and they just make you feel a bit fuller.
And those foods are high in protein.
So things like fish, the chicken we've got there.
The other important thing is we're going to have low glycaemic index.
Those are carbohydrates, which are really slowly released.
Pasta, lentils and basmati rice are low glycaemic index carbohydrates.
They are slowly processed by the gut,
so have a lasting-fullness effect.
So high-protein, low-GI foods.
That means meat, beans, lentils.
Lots of fantastic grains and cereals.
And no potatoes!
Potatoes and most rice and breads are not allowed,
because they are carbohydrates
that are processed by the gut quickly
and so don't make you feel full for very long.
This is the first of our three, personalised, diets.
And gut hormone specialist Professor Fiona Gribble
wants to demonstrate how effective it is.
Can it make the feasters feel fuller for longer?
Fiona has taken the feasters group and split them into two teams -
yellow and blue.
The blue team are eating their new, correct diet
of high protein and low GI.
Chicken for protein, bulgar wheat for low GI.
Meanwhile, the yellow team are eating the opposite,
a low-protein and high-GI meal of vegetable curry and white rice.
Both meals have the same number of calories.
But Fiona suspects that they may have very different effects.
The hormones that actually send the signals to the brain to stop eating
are actually produced very low down the gut,
so, in order to produce the hormones,
we need to get the food lower down the gut.
And, actually, protein and carbohydrates,
that are not absorbed quickly,
arrive lower down the gut
and stimulate higher levels of these hormones
that make people feel less hungry.
Fiona is keen to see which team starts to feel hungry first.
And she wants to measure if the levels of each team's gut hormones,
which make people feel full,
are different.
So we are taking both groups' bloods before and after lunch
because we're keen to see the effect of the different meals
on their gut hormone levels.
To see which team feels hungrier quicker,
we are pitching the blues against the yellows
in a strawberry-picking competition.
It's three hours after lunch,
so the volunteers shouldn't be too hungry.
Now we want you to do some work.
What we'd like you to do is to pick until you feel hungry.
If you do feel hungry, wave your team's flag, colour, up in the air,
bring your punnet up to the top
and we'll weigh your strawberries
and see how many you've managed to eat.
To pick!
Exactly! Exactly!
Exactly! So...
So just to dig the professor out of a hole,
don't eat them!
Just pick as much as you can
and the strawberries go into the baskets,
not into your mouths, OK?
After just five minutes,
our first picker starts to feel hungry and quits.
She's from the yellow team
and on the incorrect diet.
She's quickly followed by half a dozen more yellows.
They're all giving up, they're all hungry.
20 minutes later, more than half the yellow team feel hungry
and have stopped.
Still no blues.
Are you feeling hungry? No.
I'm not feeling super-hungry.
I'm not even tempted to take a strawberry.
So the high-protein, low-GI diet
does seem to be holding off hunger.
And if the blue team don't feel hungry,
they'll eat less and lose weight.
And this is what we're going to encourage them to continue to do,
because they'll get fuller quicker, they'll eat less
and they'll go longer before they have to eat again. That's right.
It's actually a natural way to increase your own gut hormones
and send these signals to your brain that say that you're full.
Yay! We're done!
It's not until eight out of ten yellows have quit,
that the first blue pickers start to feel hunger pangs.
Finally, when the last yellow has surrendered to their hunger,
the blue team are left kings of the strawberry field.
BLUE TEAM WHOOPS
The blue team, who ate the correct diet,
held off their hunger for a combined total of eight hours longer
than the yellow team.
And that's because the blue team's hormone levels are also much higher.
When she looked at the results of their hormone tests,
Fiona discovered the blue team's levels of the hormone GLP-1
kept rising for three hours after lunch.
In contrast, by then, the yellow team's were just half as high.
The second diet is for the constant cravers.
This is the group of eaters whose genes encourage them
to feel constantly hungry.
Because of their constant hunger, our nutrition scientist Susan Jebb
believes this group will struggle to diet for seven days a week.
Instead, for part of the week,
she's going to dramatically reduce their calories,
a diet that's often called intermittent fasting.
The good news is, for five days a week you don't need to diet.
You're going to do all the hard work just on two days.
Two days each week, you're going to have no more than 800 calories.
By reducing food intake on two days,
this diet should shock the constant cravers' bodies into burning fat.
Crucially, they need to avoid carbohydrates, like bread and pasta.
So, fruit's off. It's really meat, fish, eggs and veg.
The other five days a week, they don't have to diet,
but they should eat healthily.
It's 18 hours into the first day of fasting
and some in the group are starting to suffer.
It's really flipping hard, like.
I don't know how the other guys do it.
I just don't get it. So far...
It's only my first day. And I'm going to struggle, you know?
And I'm here for that. You know, I'm here to lose weight, so...
I know this is something I will have to do for quite a while, but...
It's hard.
So-called fasting is difficult,
so Giles Yeo wants to show the constant cravers the benefits.
Not only is it reducing the calories they eat,
it's also encouraging their bodies to burn fat.
To see how, they need to give a urine sample.
Hello, guys. For a good reason, we need to look at your wee now, guys.
So here's a pot.
Now, grab a cup and fill her up.
Here you go, guys.
When we eat, our bodies convert our food into sugars, like glucose.
But, when we fast and there are no sugars left,
our bodies turn to our fat reserves.
They burn them for energy instead, which is why we lose weight.
And a by-product can be seen in our urine.
We're making everyone go and have a wee. What are we looking for?
Well, when someone fasts, they start to burn sugars first, or carbs,
and the reason is because your body is looking for the easiest way out.
However, when all the sugars are gone, they start to burn fat.
And when they burn fat, they start to release ketones.
And it's these ketones we're trying to find in the wee.
Ketones are the tell-tale chemicals which show that the diet is working.
The volunteers are burning fat and, therefore, losing weight.
But, if they have even a nibble of a carbohydrate,
their bodies will switch back to burning sugars
and the ketones won't appear.
If anyone's snuck out this morning and had a Danish for breakfast,
we will know, because they won't have any ketones.
Absolutely.
Any carbs, no ketones. So we know when they're cheating.
OK, guys, we're going to test your ketones now in your wee.
So, I'm... These are test strips.
OK, I'm going to hand these out individually.
What I want you guys to do
is to dip them into your wee immediately and pull it out, OK?
Don't drip it everywhere.
And we're going to look at the colour, OK?
And I think we're going to look for shades of purple.
The negative is this beige colour thing here.
And we're looking for different shades of purple.
The darker the purple colour,
the more ketones are being produced,
and the more fat that's being burnt.
Does everyone have a stick?
ALL: Yes!
OK.
Go...
out.
Hold them up. Everyone, hold them up.
So, there are some very dark purples.
Claire's. Danille. Barbara. Morgan.
Oh, wow!
Oh, look, see? It matches your T-shirt!
You are burning fat like nobody's business.
In fact, John has as many ketones as his polo shirt.
Yeah, definitely!
So, I would say 80% of people have small or moderate. Yes.
And some people have large. Some people have amazing amounts.
I'd be interested about how some of the people with lots of ketones...
I mean, you're in an unusual state for your body.
John, how are you feeling? I'm not feeling particularly hungry.
Really? OK. That's great.
Claire?
Erm...less than I would expect.
Morgan, how are you feeling?
I'm really hungry. You're really hungry? OK.
Many of you are in a very unusual kind of bio-chemical state.
So, it may feel odd for some of you,
but your bodies will, in the next three months, get more used to this.
It's not going to get worse than this. This is how I feel.
And then that should help you get your way through, as well.
It's tough for the constant cravers, but, after two days of fasting,
all of them, to a greater or lesser extent,
are burning fat.
I think you guys...you guys with the intermittent fasting
have had the hardest couple of days.
How's it been?
Horrendous. Horrendous.
Really, really hard. Really hard.
We thought what we would reveal to you now
is how much weight
each of you has lost in the last 48 hours.
Susan, do you want to...
All of you have lost at least one pound in the last two days.
One pound!
You're not very excited by that, are you?
I think it's really good. They're not excited.
It'll be more exciting when you see how it looks.
Let me show you what one pound of fat looks like.
Urgh...!
Oh...
Here... And I find that fat blob really helpful
to visualise what all those hard efforts
have, actually, actually meant.
Next time we see you,
if you guys have stuck to two days a week of 800 calories,
what you expect to have lost
is this...
GASPS OF SURPRISE
That is five pounds of fat.
So, when the going gets tough, think of the fat you're losing.
The third and final group
to be put on a personalised diet are the emotional eaters.
They need to go on a low-calorie diet.
But again, it's difficult.
By eating when they're anxious, depressed or stressed,
the emotional eaters have developed habits which are hard to break.
People often think diets are about willpower.
Forget that. Diets are not about willpower. Yeah.
Diets are about habits.
There's never been a study that says
that people can will themselves to lose weight.
But they can change their habits. Yes.
But, first, we've got to break the old ones. Yes.
So, for you guys,
there's going to be a lot about how you break old habits.
How do you establish new, healthy habits? Yes.
That's really the focus of your programme.
One established way that emotional eaters
can create such healthy habits
is through group support.
By sharing dieting diaries, using e-mail groups
and attending weight-loss meetings,
they can encourage each other to stick to their diets.
Morning, Minnie. Morning.
Good morning, everybody! Hello! Oh, you are so cheerful.
Professor Paul Aveyard has come up with a powerful way
to show the Emotional Eaters how effective group support can be,
how it can get them over the most impossible hurdles.
Well, one of the things that's so hard about losing weight
is that your goal seems so far off and your progress is so slow.
What groups do, is that they give you a weekly goal.
Not only that, you're there with other people
who are going to help you with that.
Just as you're bonding now as a team,
in your weight loss groups, you'll also bond as a team.
And group support can really help boost your motivation.
We've set up a task today to really ask all of you to challenge yourself
in terms of overcoming stress and anxiety.
And that, ladies and gents, is to abseil down this lighthouse.
GASPS
No chance! Are you being serious?
What we are going to do is go through an exercise
where we show you how you can manage your emotions
to help each other down that rope, OK?
It will help you when you get back home, when you're trying to struggle
with your eating and managing the emotions of your eating.
Most of the group think they can't do the abseil.
But Paul wants to show them how group support can motivate them
to achieve something that seems impossible.
I'm terrified.
If you did it, can you imagine what that would be like?
No, cos I can't imagine that.
I want you to try and imagine it now.
Talk me through it. Who are you going to tell?
My family. OK.
Who in particular? My son and my daughter.
OK, imagine yourself now thinking of phoning your son and your daughter.
How good will that feel? How will you feel?
Pretty fantastic, right?
You've got to let that thought run through your mind too.
You can think, feel that emotion that you will feel.
If you can keep those thoughts going through your mind,
you'll get there. OK. Up you go.
So. what's happening in the Emotional Eaters' brains?
When the brain perceives we are in difficulty,
it triggers changes through our bodies.
It raises our blood pressure, increases the heart rate
and releases energy for our muscles.
Being in this stressed state makes it even harder
to overcome the challenge we're facing.
And that's where group support comes in.
Encouragement can activate the motivation-areas of the brain,
allowing you to overcome stress and achieve your goal.
Come on, then. Let's go for it.
I can't do it. I can't do it!
My legs are trembling. My heart's going ten to the dozen,
and I feel sick.
Rate it from zero to ten for me.
Ten. Ten? Ten's a panic attack though.
Oh, honestly.
You're looking really scared.
You going to do this, sweetheart, because you can overcome your fear.
They wouldn't put us in danger.
They're not going to put us in the heart of danger.
OK. OK.
How's that? OK?
Don't look down. Oh!
Right, let's stop now. Breathe in. That's it, and out.
Tell me your kids' names.
Gary... Gary. ..John and Mandy. John and Mandy. They're my world.
And what they going to be saying to their mother?
They would be embarrassed at the state I'm in.
They're going to be embarrassed, but then are they going to be proud?
I hope. You're going to do it. OK, look into the camera
and say, "I'm going to do it."
I'm going to do it. You're going to do it. You're going to do it.
Gary, John and Mandy, I love yous.
I love yous. I love yous guys.
They're so proud of you. They're so proud.
Susan, don't worry. You're starting to abseil now.
That's amazing. That is amazing. You're doing it, you're doing it.
Susan? Uh-huh? You can do it!
Please get me down.
You're getting down. Brilliant, she's picking up speed.
Look at that! CHEERING
Can you hear what's going on down there, that's real group support.
That is group support.
Whoo!
She did it, she did it.
Oh, my legs are killing me!
Yes!
Little bit at a time. It's all right.
That's it, good girl. You're coming. There we go, well done.
CHEERING
Good girl, well done.
Go on, Sarah!
Yeah!
Whoo-hoo!
I always would stop myself doing anything like this
because I didn't think you could. And it just proves that you can.
There's nothing we can't do now. No completely.
Yes, yes, yes, yes, yes.
SHOUTING
You can do it.
Yes! Oh, my God!
She's done it, ladies. WHOOPING
I don't think I could have done that,
if I hadn't been guided all the way.
That was absolutely amazing!
Whoa!
Whoo! MANIC LAUGHTER
Yes! CHEERING
PHONE RINGING
'Hello?' I done it!
'Oh-ho-ho! You dumb bugger.' And I...
'Did you jobbie yourself?' What?
You have no idea how bad I was, you've no idea,
but I done it, John. I done it.
'Brilliant. I'm really proud of you. pal. Well done.'
By supporting each other, the Emotional Eaters have overcome
their stress response and achieved something which seemed impossible.
And group support when dieting works similarly,
helping us to control the way our emotions respond to food.
One of the things that many people did
was they harnessed their motivation
and what you did when you were doing that
was you thought about what it was you were going to achieve,
and how that would feel.
I will feel so immensely proud,
and because you could imagine that sort of force,
it provided a kind of pull that pulled you over the ledge.
Notice the emotion, it's not that it goes away,
but that you can control your behaviour despite that emotion.
So the final message from all of this is -
and please take this now with your diets -
in the days when you think you can't do it,
contact each other, find support, but also remember this lighthouse.
Look at it, this symbolises what you can all do.
Well done, everyone. Well done. CHEERING
Has anybody got wet feet?
The first five days of our ground-breaking diet experiment
have come to an end.
Our volunteers have been individually tested
by the scientists to find out why they're likely to be overweight.
Then they've been given one of three different diets, in this new,
personalised approach to losing weight.
And now the volunteers must weigh themselves.
If they want to lose 5% of their body weight,
they need to know their start points.
I'm 18 stone 13.
I'm doing it for my 14-year-old son.
I promised him I would lose at least two stone and I won't let him down.
I'm 15 stone 13.
I'm hoping to lose at least six stone, so I can be a naughty gran.
I have no doubt you will be a naughty gran
having spent the week with you.
I'm 17 stone 3.
I really have to be brave and get past this.
This is a long journey for me.
I want to live as long as I can. I want to be with my daughter.
That's a strong mother. Thank you. And a good woman.
And you're going to do it, Sharon. I have to, I have to. You will.
Thank you. Thank you.
To lose 5%, our volunteers need to shed a total of over 900 pounds,
nearly half a tonne.
Now it's time to leave the safety and support of the Diet Lab
and head home for three months of dieting back in the real world.
Thank you all for a wonderful week. Who has had a hard week?
ALL: Yes.
Pretty much everyone. Of course, this was the easy week.
It was probably the easiest week of the next three months.
We can all do things
when we are surrounded by people doing the same thing.
We're part of a team.
And you've been supported by some of the best experts in the world.
You know your weights. You know your goals. You know your diets.
So now it's over to you.
CHEERING
Log on to
and use our diet calculator to find out
what the best diet may be for you.
And join our volunteers in the next programme,
to discover whether they can succeed
with their personalised diets in everyday life.
I think I'm starving myself.
And not losing any weight at the moment.
Gained a few. Not very good.
I was crying in there. Were you crying? Yeah.
I have lost somewhere in the region of a stone.
So I'm absolutely blown away by that. That's mind-boggling to me.