"Humanity's most fundamental relationship is with what we eat." "But nowadays, in wealthy countries, we're eating far too much of the wrong things." "There are 96 million fat people just like us!" "CHEERING" "And we're paying the consequences of our expanding waistlines with an epidemic of diseases that kill - heart disease, diabetes and cancer." "There's a complete lack of knowledge about obesity." "How did we end up in this situation and how do we fix it?" "The relationship between what we eat and how it affects our health is a story that television has been drawn to over and over again because it's never gone away." "Well, I'm greedy." "LAUGHTER" "This is the story of mankind's attempt to control nature through the wholesale industrialisation of food production in our search for enough to eat." "This is a process which we can do nothing but admire." "It's also the story of the impact this massive shift in our diet has had on the health of each and every one of us." "As a nutritionist, I've spent my career researching how what we eat determines what we are." "Of course, we now know that eating the right kind of food is crucial for good health, but it's only relatively recently we've taken that as read." "The greatest impact of the change in our eating habits is the modern-day epidemic of obesity." "In just a couple of generations, we've gone from suffering from the diseases of poverty to being afflicted by the diseases of excess." "But it's surprising how long it's taken scientists to understand the true causes of obesity and the real connection to our eating habits." "Since it was launched on the airwaves 45 years ago," "Horizon has attempted to understand this connection too, and has charted science's attempts to change how our food is produced, initially to combat the real problem of an exploding population with not enough to eat as well as trying to unearth how and why these changes" "have impacted so disastrously on our health." "The story of our bulging waistlines actually has its roots in another battle - ironically, one driven by a lack of food." "Hunger is always with us." "From the dawn of time, poverty has been the destiny of man." "Man everywhere scratched an uneasy living from an unyielding soil." "Disease and death, famine and plague were the natural order of things." "Through the course of the 20th century, a rapidly expanding population meant there were an ever-increasing number of mouths to feed." "Today it's hard to imagine, but in Europe people were still suffering from diseases of malnutrition like scurvy and rickets right up to the Second World War." "Well, the war is over, but peace hasn't brought back the plenty." "Food is still Europe's top-priority problem." "In the wake of the war, there was a great impetus to grow and provide more food." "# Hey, little hen, when, when, when" "# Will you lay me an egg for my tea...?" "#" "Industrialisation had transformed our ability to manufacture goods, and the same application of technology was now being applied to food production to feed the masses." "By the time Horizon hit the airwaves, this process was well underway." "More and more farmers were experiencing the shock of the new." "Over the last decade, scientists and experts from agricultural firms have persuaded more and more farmers to take a more drastic course, to take up what's become known as factory farming." "More and more, chickens are being produced tailor-made to fit in with the needs of the factory farmer." "One big firm brings out a new model every two or three years." "Where can the chicken go from here?" "The traditional farmyard was rapidly being modernised and the animals brought indoors to increase efficiency and enable mass-production." "The chicks are sexed, a skilled job invented by the Japanese and brought by them to Britain in the 1930s." "Today, it's possible to separate the cocks from the hens with a guaranteed accuracy of 98%." "The hens are put on one side." "The cocks, of no commercial value, are gassed." "The drive to produce the maximum amount at the minimum cost meant methods that could keep the product flowing as fast as possible, whatever the cost to the animal." "Each day, 28,000 chickens are set off down a long conveyor belt on a journey which will last 108 minutes." "Calmed by hanging upside down, they are then electrically stunned." "Now, bit by bit, the chicken is stripped down to a shell to become a convenience food." "With a pause of only 35 minutes for lunch and two breaks for tea, all day long the procession of birds goes by." "This is a process which is inevitable, a process which must go on and a process which we can do nothing but admire." "The end of the production line." "Conceived by the geneticist and realised in a factory, it's grown in nine weeks from 1.5 ounces to three pounds, the weight that the housewife wants, and at a price that most people can afford." "The march of progress was relentless." "But in their urge to squeeze maximum efficiency out of the farmyard, scientists sometimes went to extremes." "Animals kept completely free of the main farm diseases thrived, putting on weight at an exceptional rate and with much lower mortality." "By rearing a whole herd of germ-free piglets in incubators and keeping them away from other animals in a sealed-off building, commercial herds of pigs for meat have been produced that are the healthiest pigs in the country, with quite an edge over their nearest normal competitors." "Any location seemed fair game for food production if it meant an increased yield." "But some experiments were clearly destined to be abandoned." "At Hunterston in Scotland, the nuclear power station is being used for an unusual experiment." "The White Fish Authority is applying factory farming techniques to sole." "Like broiler chickens, the fish are kept in a controlled environments - in this case concrete tanks through which flows constant warm water from the power station." "This speeds up their rate of growth." "Already, they're having success." "This sole has become fully grown in only 20 months, whereas in natural conditions it would have taken three years." "Having streamlined farming, scientists now turned their attention to the rest of food production." "But what happens to food as it gets built up into more convenient forms?" "What happens to the quality?" "Take bread, a £400 million market." "It's become the ultimate in predictable products, suited to the majority of consumers." "Each piece of dough is accurate to within 1%." "It has a precise weight, constituency and measure of chemical additives, the details closely guarded from rival factories." "I'm looking for a well-developed loaf, clean." "Internally, I shall be looking for a nice white appearance, fine texture to suit the housewife for buttering, etc." "# There's a bright golden haze on the meadow" "# There's a bright golden haze on the meadow" "# The corn is as high as an elephant's eye... #" "Our attitudes to food were changing rapidly and most people embraced the new uniformity that cheap, processed foods offered." "It seemed as if science could provide all of the answers." "The British housewife is tremendously conservative in her requirements for food." "What she is looking for is satisfaction from her family." "And by that I mean that there is no rejection factor." "If one has a family sitting down, the housewife serves them a meal, she is obviously concerned and worried if two or three around the table leave." "Types of food served." "It's broken down as follows." "Cereals..." "As new production methods brought down the price of food, the possibilities for innovation appeared to be endless." "And there's certainly a convenience benefit there, if it could be done technically, to have a tray with bacon and egg and fried bread and grilled sausage and tomatoes and so on that you simply slip into the oven while you nip upstairs and get the kids ready for school and when you come down..." "It's not been tried." "And if one had a deep-frozen egg in some sort of foil dish that one actually took and dropped into a pan of boiling water..." "One might recreate the egg all over again." "It's an egg shape." "It has a shell of some sort." "You would boil it, I guess." "You know?" "And I don't know what it contains, but it could be kind of solid egg and bacon in an egg shape, or solid sausage and tomato." "But whatever it is, this is concentrated high-protein, and it is the new egg." "Artificial anything seems only a matter of time." "Already, synthetic caviar, eggnogs and whiskies have appeared on foreign markets, and enthusiasts see the day coming of the super-blackcurrant." "You know what real blackcurrant flavour is made of." "You could perhaps make a less good blackcurrant into a better one." "Alternatively, you know a great deal about what you think is nice to smell and taste." "You might be able to put together something, if not like blackcurrant - it might be as artificial in taste and smell, for example, as a Beethoven sonata, which is a purely artificial collection of noises which you think are marvellous." "So perhaps, in a little while, we could come back to a laboratory like this and smell something so much better than anything in real life." "This would be, then, the success of flavour chemistry, wouldn't it?" "The scientists thought they had it licked." "It was a revolution that couldn't be reversed." "There's no going back now." "It's all an essential part of life, providing us with full nutrition at prices possible to almost everyone." "There are virtually no more of the old deficiency diseases, no more rickets or scurvy, no more starvation." "Foods which were luxuries at the beginning of the century have now become commonplace." "The cost - uniformity, predictability, a reduction perhaps in the quality of life." "So far, it seems worth it." "It seems that the advent of intensive food production had ushered in a new era of plenty with no apparent drawbacks." "But it wasn't long before the first signs of trouble began to appear on the horizon." "One big problem humanity faced was that at least a quarter of what we grew was eaten by something else " "insects." "Scientists were quick to come to the rescue in the battle with the bugs." "As you can see, pesticides at this time are our major weapons of control." "The post-war era saw a surge in the use of newly developed pesticides, which were deployed on an industrial scale." "There are four different weeds here being dosed good and proper." "Well, the charlock doesn't like it anyway, nor the cleavers." "Not even the poppy can stand up to it much longer." "Yes, no weed escapes and the scientists' victory is complete." "Yes, he's found a beetle." "Even the home was a theatre of war in the campaign on insects, and people were happy to trust that scientists had their best interests at heart." "Spraying should be as much of a routine as sweeping and cleaning wherever food is handled." "The introduction of pesticides seemed like a great success as crop yields shot up." "But it wasn't long before the dream of pest-free farming began to sour." "The time, May 1970." "Here on the island of San Miguel, the breeding ground for California's sea-lions, some appear to be killing their young." "These great animals have 17 times more DDT in them than officially permitted in fish for human consumption." "By the 1970s, it was clear that pesticides were devastating wildlife by crippling reproductive ability and wrecking nervous systems." "And we were at the top of the food chain." "149 persons in California alone have now become ill, with hundreds more cases suspected in four other western states and Canada from eating watermelons contaminated with the pesticide." "In the town of McFarland, there have been 12 cases of cancer among children." "Six children have died." "There's a growing suspicion that it's connected with the spraying of chemicals." "Children are dying." "That's why we're here." "I've lost children." "Many pesticides were banned in the 1970s and public confidence in the food revolution had taken its first serious knock." "If such destruction was being wrought on our environment by unchecked attempts to increase food production, the impact on our bodies was equally as damaging." "Understanding the consequences of this shift to an abundant, highly processed food on obesity and related diseases was a problem that was to occupy scientists for decades to come." "It only took a generation of eating processed food before people everywhere began putting on weight." "A 1967, a detailed investigation on 500 patients from two general practices showed that half the population was more than 15% overweight." "That represents over a stone of unwanted fat." "It's no shock to us today that too many sweet things are bad." "But back in 1968, they were only just latching on to the problems in store." "The problem of overweight has partly arisen because of changing eating habits." "In a growingly affluent society, there's more food generally available." "Sales of biscuits and confectionery has doubled in ten years." "All these new foods contain sugar, which although nutritionally valueless, improves the flavour of almost any processed food - even soups, beef cubes and tinned vegetables." "As a result, sugar consumption has risen fivefold in a century and doubled in ten years." "On average, we eat two hundredweight of sugar a year each." "Meanwhile, the advertising of a highly competitive food industry encourages us to buy even more." "Butter rich..." "With a family to feed..." "Sugar and eggs..." "You can really get your teeth..." "Exotic, delicious..." "Nothing tastes so good..." "The great British taste..." "Creamy taste..." "Smell that..." "Taste that goodness..." "A happy ending to any meal." "An early hint that something was wrong with our waistlines came with the arrival on British shores of WeightWatchers." "Horizon took a look at this latest American trend." "Everyone who works for WeightWatchers is a formerly fat person who knows the misery and failure of being fat and also the tremendous triumph of beating this terrible problem." "I am your lecturer and I am a weightwatcher." "Can we have Mrs Wright?" "Come along, Mrs Wright." "Yes." "You have gained a pound and a quarter also this week." "What about those chocolates?" "Well, I must confess, I did have a couple of chocolates." "LAUGHTER" "My Appestat tells lies." "Your Appestat is not down to normal yet, so you cannot have chocolates." "No, I know." "I wish I hadn't." "Two chocolates didn't weigh a pound and a quarter." "What else did you do?" "I can't recall anything else, except..." "Except." "Yes." "Except what?" "Well, I'm greedy." "That's why we're all here." "No, truly, I don't think I've had enough of the things I should have had." "All right, Mrs Wright, we all know what you've been doing." "We'll all be watching you next week, won't we?" "ALL:" "Yes." "Yes, next week." "The developing tide of obesity was to have serious consequences, affecting the way we live and how we die." "A heart attack emergency." "After years of hidden deterioration, a man's heart has suddenly reached crisis point." "Some scientists were beginning to have serious doubts about the supposed benefits of our new diet." "If we change the pattern of food that we eat, we will certainly change the pattern of diseases that we suffer from." "But I defy anybody to tell me accurately what the consequence is going to be of going from the traditional foods to these relatively artificial and quite new foods." "I think we will have new patterns of disease." "And indeed the change in diet was beginning to deliver different ways to die." "In Britain today, one in three men will die of heart disease." "Colon cancer is now the second biggest cancer killer after lung cancer." "In Africa, it's rarely seen." "In spite of all the advances in medical technology, it's getting worse." "One explanation for the worrying shift in disease patterns was the change in what we were eating." "The diseases we have now - arterial disease, cancers, these are the things that kill us." "These are also closely connected with our long-term food intake, but not in a way which we understand clearly." "The food industry doesn't understand it any better than I do, and yet they propose to make drastic changes in our food intake not knowing what the consequences are going to be at all." "There's a complete lack of knowledge about obesity." "Why is this?" "To some extent, it's an unspectacular subject to be interested in and it's been neglected to a large extent by the medical profession." "While doctors were struggling to keep up with this rapid change in their patients' illnesses, other habits were changing too." "The other important change that's made us fat is lack of exercise." "Living in cities is unhealthy." "We take a taxi, bus or motor car when once we'd have walked." "There's been a growth, too, of sedentary jobs." "It's well known now that London Transport bus drivers have twice the coronary rate of bus conductors, cos the bus conductors run up and down stairs, and they found that a high proportion of bus drivers had much larger size trousers" "than bus conductors because they were fat gents sitting about, physically inactive." "If you should weigh 12 stone and in fact weigh 16, then your chances of death from a heart attack are 50% more." "With overweight goes high blood pressure, and that makes the heart work harder, and high fats in the blood itself, which makes it clot and cause thrombosis." "But it's not only how much we eat, but what we eat." "With the can and packet revolution has come an outstanding change in our fats." "What's important are the proportions of unsaturated and saturated fats." "These farm animals are different from those of 50 years ago." "Beef not only contains much more fat, but it's the saturated kind." "These huge quantities of hard fat are causing the epidemic of coronary disease." "It would be another 20 years before the connection between heart disease and the increased levels of saturated fat in our diet could be graphically demonstrated." "A lot of people think that obesity is a cosmetic issue, not fitting into a dress or something." "But it lies at the heart of a host of medical illnesses and diseases." "This is serum from a healthy patient." "The blood has been spun to separate and take the red cells away." "A slightly yellow colour but quite clear." "This is serum from a person who is clinically obese." "It looks almost like milk, it's so cloudy." "And what's causing that is all the fat globules and the fat that is circulating in the blood around the body." "Not only does that cause a narrowing of the arteries, slowing the flow of blood and delivery of oxygen to the tissues." "It actually causes damage and a secondary process starts which leads to further damage to those blood vessels." "If you take an organ like the heart, which is pumping away to pump the blood around the body, it needs a lot of energy, a lot of oxygen delivered to it." "If it doesn't get it, if it gets starved of oxygen, that can produce a heart attack." "We weren't just suffering the effects of our new diet in our hearts." "It was hitting us in the guts, too." "Our bowels were exploding." "It seemed that again the reason was man-made." "Modern flour milling techniques removed the fibre from our staple foods." "Horizon was on hand to explain precisely what this was doing to our digestive systems." "The colon isn't just a static tube." "It contracts like an earthworm to force the food residue along." "Painter believes that on a low-fibre diet, this residue may be stiff like tar so that the very high pressures are built up in the colon." "This can cause a blow-out in the wall of the colon, called a diverticulum." "As we get older, the large bowel may become peppered with these little blow-outs, and this is diverticular disease." "In 1975, Horizon reported on the hard-won discovery made by one man's trip to the ends of the earth." "Dr Alex Walker was trying to understand why Africans, still living on a traditional high-fibre diet, remained free from Western diseases like diverticular disease." "In this experiment, African schoolchildren are being given red dye marker pills to measure the speed of transit of their food through their bodies." "Dr Walker has found that in rural Africans on traditional diets, food passes much more quickly through the bowel than in urban whites." "In the European, food waste may stay in the colon for as long as two weeks." "In the rural Africans, it may be as little as 12 hours." "This unique work has yielded strong evidence linking transit time with disease patterns." "Throughout the world, Dr Walker has found that in communities where transit times are short, Western diseases are rarely seen." "The discovery of this connection was quickly taken back to hospital wards in the West, and doctors treating bowel disorders began prescribing fibre-rich bran, with impressive results." "I now have over 1,000 patients with irritable colons, diverticular disease and various other bowel diseases that have progressed extremely satisfactorily on a normal diet plus bran alone." "Problem solved, even if the bran came from the pharmacy rather than the canteen." "Discoveries like the importance of fibre were very significant." "But as the end of the century approached, it became clear that obesity was fast becoming an epidemic." "Scientists urgently needed to understand the root causes of the problem." "At first, the answer seemed simple." "Everyone was eating too much and exercising too little." "But this simple statement could not explain why some people were gaining weight but others were not." "The search was on to understand why." "Some believed that the answers were all in the mind." "I think this is actually a disease, and I think what is behind it is really a psychological disturbance." "Suleika had a modest overweight problem, cured by a course of psychotherapy." "Looking back, she clearly sees the psychological problems behind her fatness." "It was a defence against the responsibilities of my own femininity." "If I could be fat, I would be inaccessible to young men," "I would avoid the responsibility of making relationships with young men." "Eating can be a comfort to the unhappy and bored." "Fatness may be a way of avoiding problems." "Somebody shy may become too fat to go out." "Obesity can be a way of avoiding sexual problems and people may get fat because other people need them to be inactive and hence dependent." "While this kind of explanation suited the shrinks, it couldn't be true for everyone." "If it wasn't neurosis, then where should research focus now?" "# She's got it" "# Yeah, baby, she's got it... #" "As recently as the 1980s, scientists believed the answer to why only some of us put on weight lay in the genes that control the body's metabolism, the rate at which food is broken down and turned into energy." "They reasoned that if the body didn't burn food fast enough, you put on weight." "A view shared by members of the water ballet troupe, the Padded Lilies." "I would say that probably the reason we're fat is because our metabolism is slow." "To suddenly be 32 pounds at a year old," "I don't see any other reason for that than metabolism." "Thin people can eat a tremendous amount and still be thin." "Fat people can eat next to nothing and still be fat." "The amount I'm eating isn't what's making me fat." "My metabolism, my genetics, this combination of things is what made me fat." "The question of metabolism was a key issue for my own research." "I myself was involved in a Horizon programme in the '90s to examine if this really was the case." "One of the most common things that overweight people say to me is," ""I've got a slow metabolism." ""I eat just the same or even less than my slim friend," ""but yet I put on weight."" "Another way of putting it is," ""I only have to look at a cream cake and I gain half a stone."" "To find out if overweight people do have a slow metabolism, they brought slim and overweight volunteers into a calorimeters, sealed chambers where they could measure how many calories people were burning off by measuring the oxygen breathed in and carbon-dioxide breathed out." "At all times of day, the overweight person was in fact using more calories than their thin friend." "That came as a little bit of a surprise to us, but a great surprise to them." "We could show that, rather than having a low metabolic rate, in fact it was even higher than the lean subjects." "Every activity they did took up more energy because they had a bigger body weight to carry around." "This idea that overweight people have a slow metabolism is in fact a complete myth." "If it wasn't a slower metabolism causing obesity, then what was it?" "Could it be that obese people were simply greedy and only had themselves to blame?" "While scientists were busy searching for the causes of obesity, people who were overweight still needed to find ways of shedding the pounds." "The search was on for a magic bullet, a short cut that would allow people to eat as much as they liked while still losing weight." "We now know that the best way to lose weight, other than a healthy diet, is to exercise." "But back in the '60s even this apparently obvious idea was so novel that it was deemed worthy of a scientific experiment that drew the attention of an early Horizon." "But only some were deemed worthy of study." "At this gymnasium in London, an experiment is being conducted in exercising business executives who've had heart attacks." "Business executives have been chosen because the success of the experiment requires intelligent co-operation as well as the motivation and resources to continue with the treatment for a number of years." "That's fine." "Now breathe in." "That's good." "Are you coping all right with your side bends?" "That's fine." "Alastair Murray, a British Olympic coach, supervises the patients." "And breathe in." "And do relax." "Remember, the whole thing is to try and break this tension and keep your mind on your exercises and forget about your business for a while." "When I say as far as you can, I mean as far as you can without undue stress." "Nice and leisurely." "That's grand." "Exercise is thought to reduce the risk of heart attacks for several reasons." "It keeps the level of fatty acids in the blood down, which helps because fatty acids are thought to make the heart electrically unstable." "After a month of coming three hours a week to the gym, a patient can usually do 50% more for a given pulse rate." "What's quite clear is that for both doctors and patients, obesity is extremely difficult to cure." "There are no simple answers, and those that there are seem to work for some people and not others." "But for those who found it hard to stick to a punishing gym routine, there has always been the hope of popping a pill to lose weight." "The majority of people who are obese have too much fat in their diet." "So scientists looked at the way that fat is absorbed in the stomach and assimilated into the body." "If a drug could be made to interfere with digestion and stop fats being absorbed, then people would be able to carry on eating a lot and still lose weight." "The drug, Xenical, is manufactured by an international company, and their first trial was done in Europe." "I've had some successful diets, yeah, very much so - two stone, three stone." "But unless you live your life totally eating sensibly, it goes back on." "It's a pain." "You think, "Ooh, God, why do I do this?"" "Sue Longster volunteered to be a guinea pig." "The effects came as a surprise." "When you go to the toilet on this particular drug, it is not like going to the toilet as we know." "All of the fat that you eat that you shouldn't is converted into, like, a red oil." "Not particularly nice." "And the whole of the time I was on the trial, the stools were not what you would be used to, if that's the right way to put it." "Sue found that she had to stick to a really low-fat diet and could never afford to let it slip." "But on holiday - obviously other people cooking for you and you're not able to look at what you're eating - this had an extreme effect." "We were in this shop and it wasn't particularly nice." "And I must stress to people, if you do take the drug, watch out." "And that's the key to the way the drug works." "Its slimming effects could largely be the result of aversion therapy." "The diarrhoea can be so unpleasant that patients don't dare to eat fat." "Not everyone would have the willpower Xenical demanded to avoid the heavy penalty for slipping off the wagon." "There was still demand for a drug that could suppress the appetite to bring down weight." "In 1994, two drugs that were already on the market were combined." "Together, they became very potent and users lost around a fifth of their body weight." "The drugs looked like a miracle cure and became affectionately known as Fen-Phen." "I lost 64 pounds when I was on the Fen-Phen drugs and I loved every minute of it." "The weight just literally fell off of me." "It was amazing how rapid the weight loss was." "The Fen-Phen drugs changed something in my brain and I no longer craved..." "Sugar-free Diet 7 Up." "I was, like, drinking water, and I no longer craved the fatty foods that I'd always loved, and I no longer craved all the bad things that I wasn't supposed to eat." "I could go through a room full of pizzas and never look twice at them." "Fen-Phen took America by storm." "Over six million prescriptions were issued in 1996." "But by then something had already started to go wrong." "This is my liver and my kidneys and my spleen, it's all swollen." "I look like a man that's pregnant." "But I've always wanted to be skinny and I'm skinny, but I'm not healthy." "All Carla wanted to do was to lose weight, but she began to feel ill just five weeks into her course of treatment." "I had gone to chaperone my middle son's homecoming dance and I was up dancing with the kids and just having fun with them, and all of a sudden my head started pounding and my ears started ringing so loudly" "that I couldn't even hear the music." "I went to the hospital and the next day they transferred me to Salem, and he came into the room and he told me that I had primary pulmonary hypertension and I had two years to live." "Fen-Phen seems to have caused a rare but lethal side-effect." "The blood vessels that go to Carla's lungs have constricted and her heart is now failing." "Primary pulmonary hypertension, or PPH, has now damaged all of Carla's internal organs." "The search for a wonder drug to cure obesity clearly wasn't at an end." "But the seeds to our modern understanding of the causes of obesity were actually planted 40 years ago." "In a little-known study from an era before the modern ethics committee, scientists took a completely different approach to the problem." "They didn't examine fat people, but concentrated on thin ones instead." "In 1967, the inmates of a Vermont state prison were approached by medical researcher Ethan Sims to take part in a unique experiment." "He wanted to find out about the hormonal changes in our bodies when we become seriously overweight." "And in order to study that, he needed to take a group of people and make them fat." "Very fat." "The study called for each inmate to gain 25% of their body weight." "In return, they were promised early release from jail." "Over the course of the year, the team fed the volunteer prisoners as much as they could physically eat and carefully monitored their bodily changes." "But as it went on, Dr Sims became concerned by an unexpected finding." "However much they ate, some of the prisoners could not reach the target." "Two of the prisoners got stuck at 21% and one of them couldn't put on any more than 18% extra body weight, despite eating as much as 10,000 calories a day." "the experiment pointed to a fascinating and unexpected conclusion." "It seemed that for some people becoming obese is not just unlikely, it's practically impossible." "It would be some time before the importance of these findings was accepted." "In the meantime, people continued to be attracted to any dieting fad that claimed it would work." "Then new evidence emerged supporting the theory that some of us are born to be thin in the form of a very special pair of sisters." "Twin sisters Sharon and Debbie are taking their very first holiday together at the age of 46." "They were brought up by two completely different families." "They didn't even know one another existed." "They were separated at birth and were only reunited a year ago." "We didn't know that we were identical twins." "We just knew we were twins." "So I see her coming out and I keep staring at her and she keeps saying, "Don't look at me."" "It was too intense a feeling." "And then everybody goes, "Ah, so it's like looking in the mirror,"" "and we're like, "No, dummy." "When you look in the mirror, that is you!"" "The similarities are striking." "Over the years, there's been little variation in their looks, their heights and their weights." "When they finally met, there was only five pounds difference between them." "What is astonishing is that they could not have had more opposite upbringings." "Sharon lives in Kentucky and was brought up as a Catholic." "She didn't worry about her diet, loved meat, particularly pork and fatty foods." "Oh, look." "Alligator AND pork!" "She also did very little exercise." "Debbie eats fish but not meat." "She lives in New Jersey and was brought up as a Jew." "Unlike her twin sister, she exercises regularly and is very health-conscious." "Sharon and Debbie are the perfect experiment." "Carbon copies of each other, they are living proof of the power of genes." "Their separate environments have hardly influenced their weight." "It seems they were born to be slim." "If it really is the case that some people are born to be thin, could the opposite also be true?" "By looking at my family and the large number - no pun intended - of fat people in my family, it just to me seems inevitable that I would be large." "This is my natural look because it's what I've been given from my generations of predecessors." "Maybe we've all been judging the obese too harshly." "Chronic weight gain is a modern-day phenomenon." "But could an ability to store fat have actually played a crucial role in our evolution?" "According to obesity geneticist Dr Eric Ravussin, our hunter-gatherer ancestors had to live off whatever they could find." "Sometimes that wasn't much." "Which is when fat as an efficient storage system really came into its own." "Populations went through periods of feast and famine." "During the periods of famine, maybe two-thirds or three-quarters of the population would disappear." "But those who were chubbier or those fatter babies would survive and then procreate themselves and pass on these genes." "So, according to this theory, at times of famine it was literally a case of the survival of the fattest." "The cycles of feast and famine that humankind has been subjected to was an important natural selective process, in which all the babies or the people a little bit chubbier would survive the periods of famine and then be able to gain the weight during the period of feast." "This could explain why large parts of the population have a tendency to lay down fat stores easily." "It's only very recently in human history that this has become a problem." "Now, the feast is constant." "You have food available every corner, very cheap, very palatable, and this is really a perfect mixture to provide the expression of these genes and confer obesity and weight gain to these people." "So if evolution was selecting for fatness, the question remained as to what was compelling those individuals to put on the pounds." "Scientists suddenly clocked that maybe what they should be looking at was what was driving us to eat so much - our appetite." "Proving its importance was a different matter." "But what followed was a complex tale of scientific detective work, involving a German boy with an unusual brain condition and a fat mouse." "The idea that there's an evolutionary-based, biological drive to eat is clearly an interesting idea." "But until recently, it just remained that, just an idea." "Most people believed that our appetites were controlled entirely by willpower and voluntary action." "We've discovered in the last few years that our brains are actually hard-wired to eat." "28-year-old Sven's life is dominated by the drive to eat." "He could literally eat himself to death." "It's not a question of willpower or choice." "No matter how much food he consumes, he always feels hungry." "For doctors, Sven demonstrates that there is some sort of hard-wired switch which turns a hunger on or off" "and his had to be faulty." "But Sven wasn't always like this." "Until he was seven, his appetite was completely normal." "Then he had an operation to remove a brain tumour." "From that day on, he ate and ate." "Sven is only this slim because of enormous efforts on the part of his family and his doctor." "What happened was that the operation to remove the tumour somehow damaged his hypothalamus, an important nerve centre in the brain." "Damage to his hypothalamus is what changed his eating behaviour." "Actually, we know that patients who have this tumour, they don't die because of the tumour." "Most of them die because of the overweight that they develop." "Something in Sven's hypothalamus had to be keeping him hungry." "Scientists knew that the hypothalamus was involved in switching the appetite on and off." "But decades of research had brought them no closer to knowing exactly how." "Then along came a big fat clue." "From the day it was born, this mouse had never stopped eating." "Researchers spent ten years comparing this mutant mouse with other thin mice." "And unexpectedly, they found the answer in the fat cells of the thin mouse." "Scientists already knew that if we overate fat cells blow up like balloons to hold more and more fat." "But to their surprise, the research team found that the fat cells were also manufacturing a hitherto unknown hormone, leptin." "To find out that the fat cell was itself producing a hormone and actually actively participating in a communication network was again revolutionary." "It's changed the way we view fat tissue ever since." "It's not as dumb as we thought." "A dumb cell was turning out to be a smart storage system." "The fat cells of the thin mice were manufacturing lots of leptin." "The researchers quickly discovered that the obese mouse had none." "So researchers gave the fat mouse leptin to see if it would stop eating." "The results were profound." "The mice lost 40% of their weight after just four weeks." "What goes through my mind is that maybe we've got our first handle on understanding what the molecules are that control body weight, and the hairs on the back of my neck stood on end." "It was wonderfully exciting." "The news that leptin made fat mice thin in a matter of weeks had a massive popular appeal." "Researchers then looked at humans and discovered that the hormone leptin was a messenger molecule for us, too." "It travels up to the appetite control centre in the brain, the hypothalamus." "The hypothalamus acts like a thermostat." "So if body fat increases, the leptin increases and appetite goes down." "When we lose fat, leptin signals become weaker and we eat." "It's very clear now that there are several biological mechanisms that determine how much fat each individual maintains in their body, and any change, either by gaining weight or losing weight, is actively resisted." "This is true for people who are mildly overweight or people that are grossly obese." "Cathy looks just great in hand-dyed, original button-down front in a full circle dress." "Beautiful, Cathy." "So the hormone leptin maintains fat at a steady level and makes dieting very difficult." "Fat people have their leptin thermostats set high." "They can be reset, but it seems to be much easier to reset it up than down." "So it's easier to get fat than thin." "It seems as if our biology is happy at the particular body composition that we are, and if our health requires that we need to change our body weight to improve our health, it's a massive struggle that's a day, by day, by day exercise." "The discovery that there are genetic variations that govern our response to leptin, and therefore our appetite, forced even expert doctors to change their attitudes to their obese patients." "I really judged them as being not strong enough to control their body." "But now I really know that there are genetic defects that we can't control, that force us to eat, and I feel sorry for my patients that I have misjudged and that I have been cruel to." "Inspired by their richer understanding of obesity that leptin had given them, scientists returned to their search for a wonder drug." "This top-secret research facility is where the war against obesity is being waged." "Here, millions of pounds are being poured into the hunt for a magic bullet, a drug to treat the disease." "John Clapham is at the front line of this research." "To find an effective treatment for obesity is of paramount importance." "And the mission is to find a pill to kill hunger, a pill that works by manipulating our desire to eat." "To do this, they need to map out all the chemical signals in the appetite pathway." "Because every one of those is a potential new drug target, and the more drug targets we've got to work on, the chances for success are much greater." "And we have every hope in the future of getting a new drug." "As suspected, leptin and melanocortin are turning out to be just the tip of the iceberg." "We now know about a number of other chemicals in the brain that act to regulate appetite." "We know there are some that act to decrease appetite... ..such as the melanocortins, the neuromedins... ..POMC, the melanocortin receptor, CART..." "There are those that decrease appetite, such as the orexins, galanin..." "Neuropeptide Y..." "There are a number of peptides released from the gut that affect appetite, such as glucagon-like peptide-1, enterostatin, cholecystokinin and on and on and on." "We're expecting more discoveries all the time." "But even with all these drug targets, they still have a long way to go." "In terms of drug treatments for obesity, we're lagging 20 years behind other avenues of research." "We're at the beginning of a long road now and even if a treatment were to be identified tomorrow, then we're looking at 10, 12 years before any treatment is actually available." "It's hard to know if any new obesity drug will ever really work." "As we've seen in our journey from malnutrition to obesity, there have been many false dawns." "From the disastrous effects of pesticides to the collapse of our fibre-deprived colons, and the tragic side-effects of some diet drugs." "Unlike the progress medicine has made in treating other major diseases, we still don't have a medical solution for obesity." "Fat is sexy, fat is fine, you've got yours and I've got mine." "Some have decided to embrace what nature has given them." "But for those who want to fight the flab to improve their health, they're left with the timeless mantra of a healthy diet and lots of exercise." "If we've learnt anything from this story, it's that nutrition is a complicated science." "Each new discovery only throws up new questions about the relationship between what we eat and our long-term health." "But perhaps that's just the very nature of science itself." "Subtitles by Red Bee Media Ltd" "E-mail subtitling@bbc.co.uk"