WE all know what the problem is: The western world is full of overweight people, an estimated two billion according to the World Health Organisation. Many people claim to know the answer: Put them on a diet so they eat less. Problem solved.
Except they overlook one thing - diets are not the solution to the problem because in many cases they are the cause of it. Diets play havoc with the mind and the body and 95 per cent of dieters regain the weight they've lost.
As Dr Adrienne Key, of the Royal College of Psychiatrists, told the parliamentary group on body image: "Getting rid of dieting could wipe out 70 per cent of eating disorders. Get rid of dieting."
You may only have thought acute conditions like anorexia, bulimia and binge eating were eating disorders. You'd be wrong. Constant, drastic dieting is not normal behaviour and many experts now consider it is one of the major factors contributing towards the obesity epidemic. A diet is really disordered eating.
The UK has the highest rate of eating disorders in Europe with an estimated 1.6 million sufferers, and between 11 and 13 million people are on a permanent diet, according to official figures. Spot the link?
As this is National Eating Disorders Awareness Week it's the perfect time to consider some of the scientific evidence about dieting and its horrendous psychological effects which often manifest in low confidence, obsession with calories, deprivation, binge eating and generally feeling out of control.
The diet industry has only been around for about 50 years - up until the 1960s we were slimmer and dieting was rare. Post-war austerity meant we had less money to spend on eating and junk food - additive-rich, fructose-packed fast food and ready meals - hadn't arrived on our shores.
The way food - or more precisely, lack of it - affects our behaviour was discovered as long ago as 1944 in the Minnesota Starvation Experiment, also known as the Ancel Keys Study.
In this, 36 men voluntarily halved their calorie intake for six months. The physical changes were dramatic, with significant reductions in the men's strength, stamina, body temperature, heart rate and sex drive.
For me, the psychological effects are even more worrying. Hunger made the men obsess about food. They would dream and fantasise about it, read and talk about it and savour every mouthful of the two small meals they were given each day. They reported fatigue, irritability, depression and apathy.
This is such a familiar story; I hear it all the time both in Harley Street and at Thinking Slimmer from people who've spent years on diets. The only way they can hope to lose weight is by changing their behaviour towards with food and thinking the way slim people think.
Disordered eating is the reason so many people seek therapy. They have a rubbish relationship with food and years of dieting have taken their toll, so much so they've forgotten how to eat normally.
There's a remarkable book I recommend every overweight person should read, Diets Still Don't Work, by Bob Schwartz PhD. Bob was a health club owner in America in the 1980s who'd been on diets himself without ever achieving lasting weight loss. He reckoned he'd done almost 100 diets in 10 years and lost 2,000lbs - and yet he was heavier than when he started.
So he studied the gym records of his customers and discovered that they'd nearly all suffered the same fate. That's when Dr Schwartz had a lightbulb moment.
Lots of people came to him because they were skinny - so he decided to put them on diets, depriving them of their favourite foods, to see if they would put on weight. Guess what? They did. Dr Schwartz was one of the first to establish that diets make you fatter in the long term.
One reason for this is something I have come across many times in my work as a behavioural change specialist. Put simply, when we're deprived of something, our brains are hard-wired to make us obsess about it.
When you're on a diet you're supposed to think less about food, but just the reverse happens. Dieters think about food all the time. They even dream about eating. It's a sad truth that only overweight people on diets know about calories - slim people have no clue and just eat normally.
When an eating plan dictates people can't have cakes, biscuits or chips, that's all they can think about. Says Dr Schwartz: "It's not weight that's the real problem - it's the mentality behind it. Get rid of the mentality, and the weight comes off by itself, as quickly and as naturally as it was put on."
How can we hope to end millions of people's obsession with food unless we can first cure their obsession with dieting?