Why it's so hard to keep fat off & what you can do about it

by Nicky Pellegrino / 16 August, 2016
Getting the weight off is one thing; keeping it off quite another. But new science is shining a light on the business of dieting.
Photo/Getty Images
Photo/Getty Images


Craig Davies has only positive memories of the TV weight-loss show he took part in in 2007. One of the earlier examples of the genre, Fighting Fat put five people on different diets and offered them the support of a psychologist and a dietitian.

“It was all very well done,” recalls Davies. “At the time, I weighed about 130kg. I was put on the Eat Right For Your Blood Type diet, which really worked, and I lost 15kg.”

The Auckland man ended the TVNZ show on a high and full of good intentions, but within six months, the kilos were building up again. A knee injury prevented him from exercising and a new, more sedentary job with a security company involved lots of driving and easy access to unhealthy foods. He regained not only all the weight he had lost during the filming of Fighting Fat but also a great deal more: he peaked at 200kg.

“I tried every diet: Weight Watchers, Optifast, a doctor who handed out amphetamines like candy,” he says. “I’d lose a bit, feel better, put it back on, feel guilty and then think, ‘What is the point?’ I was in a cycle.”

Kevin Hall: reality TV meets biomedical research.
Kevin Hall: reality TV meets biomedical research.


Fat-busting reality shows are in an endless cycle of their own. The most popular, the US series The Biggest Loser, has spawned more than 30 international versions, including in Australia. Obese contestants sign up for boot camps of intense exercise and diet. The one who has lost the most weight at the finish gets the cash prize.

The winner in season 8 in 2009, Danny Cahill, was dubbed “the biggest loser ever” after shedding an astonishing 108kg – more than half his body weight – in seven months. But like Davies, once he returned to normal life, the weight began to return. Within a few years, he had regained almost half what he had lost.

This was devastating for Cahill but a gift for science, as Kevin Hall would attest. A scientist at the National Institutes of Health, America’s (and the world’s) largest biomedical research agency, he is also a fan of reality TV and he followed 14 contestants from season 8 of The Biggest Loser and measured long-term changes in their resting metabolic rate (RMR) and body composition.

Your RMR determines how much energy you burn simply to stay alive – to keep your heart pumping, your digestive system working, your lungs breathing. It was already known that when you lose weight, your RMR slows, in what is known as metabolic adaptation or adaptive thermogenesis. (It is part of the body’s defence system against possible famine.)

So it was no surprise to Hall and his team that the RMR of contestants dropped substantially after the competition. But it was what they found when they checked them six years later that shocked them: many subjects had regained much of the weight they had lost but their RMR remained suppressed at the same average level as at the end of the show, when they were much lighter. So they were burning about 500 fewer calories a day than expected given their age and body composition.

What was worse, changes in hormone levels conspired to make them hungrier. Leptin, the so-called satiety hormone, is made by fat cells and helps to regulate energy balance by inhibiting hunger. Its production declines with weight loss and should increase with weight gain. But in The Biggest Loser contestants, it did not return to its original levels: they were fat again, even hungrier than before and burning fewer calories.

An internationally renowned investigator of obesity management, Melbourne endocrinologist Professor Joseph Proietto, explains that leptin is only one of a number of hormones controlling hunger. His study of overweight people who had lost an average of 13kg found a fall in levels of leptin and four other satiating hormones. At the same time, there was a rise in levels of ghrelin, the hormone secreted in the gastrointestinal tract when your stomach is empty to tell you you’re hungry.

“More recently, we showed that after three years, the leptin was still lower and the ghrelin higher for these people,” Proietto says. It made no difference whether weight loss was gradual or rapid; the body’s mechanisms worked to return it to its previous weight set point.

“It’s really hard not to eat when you’re hungry,” says Proietto, who is now investigating at what level of weight loss these hormones start to change.

Craig Davies: “I’d lose a bit, feel better, put it back on, feel guilty.” Photo/Rebekah Robinson
Craig Davies: “I’d lose a bit, feel better, put it back on, feel guilty.” Photo/Rebekah Robinson

Pick your plan


The diet market, worth billions and rising, is full of conflicting advice. Yet research has shown that it doesn’t matter which eating plan you follow. If it suits you and you stick with it for long enough, you will lose some weight, according to a study published in the Journal of the American Medical Association two years ago. The trouble is that about 80% of people regain that lost weight.

Rena Wing has studied the habits of the 20% who don’t. A professor of psychiatry and human behaviour at Brown University, she established the National Weight Loss Registry in 1994. Its members are a self-selected population of dieters who have had long-term success – defined as shedding at least 10% of initial body weight and keeping it off for a year. They report engaging in high levels of physical activity, eating a low-calorie, low-fat diet, eating breakfast regularly, monitoring their weight and maintaining the same eating pattern on weekends as on weekdays. The longer they keep off the kilos, the more chance they will continue to.

That is all very well, says Proietto. “But if something bad happens in their lives and they get distracted from frugal eating and heavy exercise, their biology will take them back to where they were.”

Davies and his fellow Fighting Fat contestants.
Davies and his fellow Fighting Fat contestants.


He believes the solution is to develop medication designed not to aid weight loss, but to maintain it. “The ideal treatment would be to replace the hormones and return them to natural levels. We know leptin on its own doesn’t work; most people are leptin-resistant if you replace it to the level it was before. It doesn’t make biological sense to use a single agent. What we need urgently is more of these hormones to be made and then we can combine them. I don’t think we can go wrong if we mimic nature.”

Support is the other thing that might make a difference. In the US, a weight-loss programme called TOPS (Take Off Pounds Sensibly) promotes healthy eating, but doesn’t insist on any particular plan, and costs very little to join. The programme, which began in 1948, is a low-profile not-for-profit and weekly meetings provide a supportive and educational environment, with regular weigh-ins for those losing kilos or trying not to regain what they have already lost.

Nia Mitchell, of the University of Colorado, came across TOPS while looking for a programme her patients could afford. Realising no one had done any research on it, she embarked on an analysis of the organisation’s database, focusing on those who had lost 5% of their body weight over one year.

Of those who participated through a second year, 80% kept the weight off. By year seven, 95% of participants who continued in the programme had maintained the weight loss. These results sound remarkable, but the numbers are skewed by the vast dropout rate. By the end of year seven, there were only 779 of the original 65,559 participants left; the rest were lost to the team’s tracking and are assumed to have regained the weight.

“What this implies is that continuing to engage in a weight-loss programme can lead to extended maintenance,” says Mitchell. “Group settings work for a lot of people.”

Mitchell says the challenge is to find a way to keep people engaged indefinitely in a maintenance programme.

The season 8 contestants in The Biggest Loser included Danny Cahill (top right and below). Photo/Getty Images
The season 8 contestants in The Biggest Loser included Danny Cahill (top right and below). Photo/Getty Images

A perfect storm


However, she may be swimming against the tide. Diets, no matter how sensible, are falling out of favour with a growing number of experts. The new obesity philosophy holds that we are in the middle of a perfect storm. As if long-lasting metabolic adaptation and unco-operative hormones were not enough of a challenge, we now live in what is described as an “obesogenic” environment: processed foods high in salt, sugar and fat are widely available and heavily marketed; modern life (all that screen time) is steadily becoming more sedentary. Add in a genetic predisposition to gain weight and it’s not our fault we’re getting bigger, the argument runs. The odds are stacked against us.

This isn’t entirely new. In the 1980s, pioneering psychiatrist Albert Stunkard found that fatness is in your genes. Using data from the Danish adoption registry, he found there was no correlation between the weight of children and their adopted parents. However, if both their biological parents were obese, there was an 80% chance they would be too. Stunkard followed that up with a study of twins separated in early life and found their body mass index was nearly identical.

Subsequent studies have identified genetic variations linked to obesity. The thinking is that if you are saddled with several of these, you are likely to survive well in a time of famine, but the super-size-me era would not have gone so well for you.

Such research, as well as personal experience, changed Auckland endocrinologist Robyn Toomath’s attitude to dieting. In November, she shut down Fight the Obesity Epidemic, the advocacy group she had founded 14 years earlier, and in the book, Fat Science, she explores the reasons recommending diet and exercise to the obese isn’t going to work.

Danny Cahill, who soon regained half the 108kg he lost. Photo/Getty Images
Danny Cahill, who soon regained half the 108kg he lost. Photo/Getty Images


Toomath no longer advises her patients to lose weight because she has seen too many motivated individuals fail. She accepts that obesity is a result of biological, social and environmental factors and says any efforts to tackle it have to recognise that. “Governments need to declare that obesity is a major problem and make reductions in obesity rates a health target.”

She isn’t encouraged by initiatives such as the recent voluntary agreement by Belgium’s manufacturers and retailers to cut the nation’s calorie intake by 5% by next year. Voluntary efforts are rarely successful, she argues, and what is needed is a comprehensive food policy that guides all sectors. “Trade, transport, treasury, agriculture and education have much bigger roles than health in correcting the obesogenic environment.”

Population science is showing us the way. A University of California study has shown that the proximity of fast-food outlets to school influences child obesity rates. And a UK study found the way we travel to work makes a difference: public transport users are less likely than car drivers to be overweight; cycling reduces the chance of diabetes; walking makes hypertension less likely.

Among the strategies Toomath suggests are improved food labelling; a ban on junk-food advertising and sponsorship; controls on siting of fast-food outlets; a tax on sugary snacks and soft drinks; and town planning that encourages us to get out of our cars.

She isn’t absolving the individual of every shred of responsibility. Constantly astonished by the terrible food served up at medical conferences – doughnuts, pastries, popcorn and chocolate bars – she believes we all need to influence the environment over which we have control: “For some, that will be our own household, but for many it could be our workplace, school or church.”

Her emphasis now is on eating for health rather than weight loss – home-cooked meals instead of takeaways, ordinary fruit and vegetables rather than pricey superfoods. “I would like us all to see food differently,” she says. “At the moment it’s a commodity – just another way to make money.”

Danny Cahill, who soon regained half the 108kg he lost. Photo/Getty Images
Danny Cahill, who soon regained half the 108kg he lost. Photo/Getty Images

Lost causes


Policy changes and public-health interventions may be the appropriate response to the obesity epidemic, but they seem like next-generation stuff. Should we accept that the obese are a lost cause? Is the best we can do for them to help manage their associated health problems?

“The short answer to this is yes, although I wouldn’t describe anyone as a lost cause,” says Toomath. “Individuals suffering with obesity need to be treated with compassion and their health issues addressed. And obese young women need to understand that eating as healthily as possible during pregnancy, not smoking, and breastfeeding the baby all seem to reduce the child’s obesity risk.”

The consensus is that we are not doing enough to ensure the next generation don’t follow in our heavy footsteps. High rates of obesity have been identified in the under fives. But there are encouraging initiatives. The Waikato District Health Board’s Project Energize is working with 44,000 schoolchildren to improve nutrition and increase physical activity. Their obesity rates are 3% lower than the national average and the kids appear to be fitter.

From top, Nia Mitchell, Joseph Proietto, Robyn Toomath: battling obesity on many fronts.
From top, Nia Mitchell, Joseph Proietto, Robyn Toomath: battling obesity on many fronts.


A 2014 review, published by the Ministry of Health, recommended that toddlers and preschoolers get at least three hours of physical activity a day and be sedentary for no more than an hour at a time (excluding sleeping and eating). In a pioneering study in low-decile early childhood centres, researchers from Massey and Waikato universities have teamed up with physical activity programme Jumping Beans and are using wearable activity trackers to see how best to maximise physical exercise opportunities for preschoolers.

For adults who are already morbidly overweight, the only beacon of hope is bariatric surgery. The Biggest Loser study found that a group of patients who’d had the gold-standard weight-control surgery, a Roux-en-Y gastric bypass, experienced metabolic adaptation six months after the surgery, but at one year it had disappeared, despite continued weight loss. Researchers speculated that bariatric surgery may help permanently reset the body’s set point – the weight it wants to return to.

Bariatric surgery also prevents ghrelin sending out those hunger signals, and for the first time a patient feels full. To begin with a meal is just two to three teaspoons of food; by six months it is still only half a cup.

But gastric bypass isn’t a magic bullet. Nurse Kate Berridge has worked with patients at Auckland’s Middlemore Hospital and has now set up her own business, Beyond Obesity, designed to provide the support and follow-up she believes is lacking in the public system to help prevent post-operative weight gain.

“After surgery, people are on the ceiling, life is fantastic,” she says. “But about 18 months later, their weight plateaus and that is when they can start to fall over. The hospital doesn’t want to follow the patients through forever. It’s not the DHB’s brief to look after them long term. They want them put back in the GP system; and no disrespect to my GP colleagues, but they don’t understand obesity.”

About 60% of patients learn to live with their new smaller stomachs. They may regain some weight but they’ll exercise, take vitamins, make good food choices and enjoy the health benefits. Berridge is concerned with the other 40% and identifies the critical period between 15 months and five years after surgery as the time they need ongoing support.

“There are hundreds of people out there who have regained weight and won’t go back to their surgeons because they feel ashamed,” she says. “I know they’re out there and I want to reach them.”

Berridge sees her role as teaching people not only how to eat differently but also how to think differently. She has developed a self-care management programme, and through group sessions and one-on-one consultations, she encourages patients to let go of the shame and self-hatred, the sense that they are losers who lack willpower, that they will never be good enough.

Kate Berridge: “For some people, the surgery isn’t what they expected.” Photo/Simon Young
Kate Berridge: “For some people, the surgery isn’t what they expected.” Photo/Simon Young

Watch what you think


“For some people, the surgery isn’t what they expected. It hasn’t fixed all their problems,” says Berridge. “Shit still happens.”

Those are the people who will continue to self-medicate with food and alcohol and start to regain the weight they’ve lost. Instead of putting them on a diet, Berridge encourages her patients to record what they are thinking as they eat. She teaches them to separate “head hunger” from “real hunger” and recommends a mindfulness technique called urge surfing to manage cravings.

Rather than suggesting they never eat another square of chocolate, she quotes Canadian obesity expert Yoni Freedhoff who says: “It’s about living the healthiest life that you can enjoy, not the healthiest life that you can tolerate, because if your life is simply tolerable, you’re not likely to keep living that way.”

Almost a decade after appearing on Fighting Fat, Davies finally underwent bariatric surgery. He is back down to 130kg – his weight when he went on the TV show.

He lives on a high-protein diet, with lots of chicken and fish, and is hoping that recent knee surgery will mean soon he will be able to walk properly, start exercising, return to his old hobby of hunting and shed more kilos.

“I’ve got my life back,” he says. “I feel better, have more energy, my daughter tells me I don’t snore any more – she calls me the incredible shrinking Dad.”

The future looks lighter


Technology is tackling a major cause of disease and death.

  • Wearable technology is helping to provide new weight-loss tools. A study at Clemson University in South Carolina found that young adults fitted with a bite-count feedback device significantly reduced their intake of food – although those served meals on larger plates still consumed more than those given small plates. Researchers believe bite-count feedback is an excellent weapon against the so-called “mindless margin”, the amount we eat without really thinking about it.

  • A computer game that trains the brain to resist unhealthy food is being developed by researchers at Drexel University in Philadelphia. The game, DietDash, is designed to improve inhibitory control in the part of the brain that stops us giving in to unhealthy craving. “Studies have shown that if you do certain tasks that involve this inhibitory control over and over again, it actually gets stronger,” says professor of psychology Evan Foreman. The same researchers are also working on a phone app that intelligently detects patterns in a person’s eating habits. When users are likely to slip from their dietary plans, the app provides tailored strategies to put them back on track. In a recent study both types of training were successful in reducing snack eating.

  • A single dose of an oxytocin nasal spray has been shown to reduce food intake and suppress impulsive behaviour in overweight and obese men. Harvard Medical School researchers tested this synthetic form of the hormone and discovered it boosted self-control, although they’re still not sure how.

  • A new non-surgical intervention is being developed by radiologists and may offer an alternative to gastric-bypass procedures. Bariatric arterial embolisation targets a specific part of the stomach, the fundus, which produces the majority of the hunger hormone ghrelin. Injecting microscopic beads to decrease blood flow to that portion of the stomach suppresses some of the body’s hunger signals. In a pilot study at Johns Hopkins University School Of Medicine, seven severely obese adults who had the procedure all demonstrated weight loss and dramatic hunger-reduction levels. Ghrelin levels trended down and quality-of-life scores improved.


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