Why diets fail and how to succeed

New research published today in the New England Journal of Medicine reveals that the body does everything in its power to induce weight gain after a diet, which partly explains why diets fail in the long term.

Researchers put 50 overweight and obese people on a low calorie diet for 10 weeks and at the end of the diet examined participants’ hormone levels over a one-year period.

Their findings revealed that levels of the hormone leptin, which is an appetite suppressant, went down while levels of the hormone ghrelin, which is an appetite stimulant, went up.

In other words the body is doing everything it can to regain the lost weight, which partly explains why diets fail. Study participants also said that their appetites increased over time after the diet ended.

Whilst the body is releasing hormones causing increased appetites, keeping the weight off can be a major challenge, especially if we cannot control compulsions to consume junk food – and here’s why.

A study in 2010 led by Associate Professor Paul Kenny at the Scripps Research Institute in Florida, found that junk food is as addictive as heroine.

Laboratory rats were placed on two diets: a typical salad diet and a junk food diet consisting of sausages, bacon and cheesecake.

The findings revealed that the rats fed junk food quickly became compulsive over-eaters and even endured electric shocks to satisfy their food cravings.

They also developed an aversion to healthy food as when researchers tried to place the junk food rats back on the salad diet they refused to eat. An examination of the brains of the junk food rats revealed similar neurochemical mechanisms in place associated with drug addiction.

The findings confirm long-held suspicions that the over-consumption of junk food causes chemical changes in the brain that induces compulsive eating.

So whilst our hormones are telling us we’re hungry and that we should eat, the moment we succumb to that bar of chocolate, cake, pizza or burger, our brain releases chemicals that cause us to carry on eating and the pounds it took six months to shed pile straight back on in half the time!

In a study published in the American Psychologist in April 2007, researchers reviewed studies on the long-term effects on dieting to help determine the best methods of treating obesity.

Their findings revealed that whilst diets are successful in the short-term, the weight loss is not maintained in the long-term, and once a diet ends, the more time that elapses the greater the weight gain.

On a more positive note, researchers found that exercise helps to maintain weight loss. Analysis of several studies found that dieters who exercised regularly kept more weight off than those who did not.

But the researchers said that overall their findings point to dieters that gain back more weight than they lose being the norm, rather than the exception.

As a self-confessed, though unintentional yo-yo dieter, I can readily identify with the findings of these studies. The only reason I became a yo-yo dieter was because each time I lost two stone it went straight back on, usually within a year, forcing me to diet again to lose it.

That is precisely why I embarked on my Lifestyle Challenge – to avoid the dieting syndrome and make permanent changes to my approach to health, which includes moderate daily exercise that I can easily maintain.

To date my weight loss has been steady and I am pleased with the results so far, but admit it has been challenging. Whilst I love the food I have been eating  – lots of fresh fruit and vegetables, eggs, fish, chicken and beef – I have succumbed to junk food on a few occasions when away from home.

I have learned through experience that it is futile trying to avoid highly palatable foods on a permanent basis – since the more you deny yourself the foods the greater the compulsion to eat them.

So yes, now and again I do allow myself some indulgences – but if I break from my healthy eating plan then I will follow this up by reducing my intake for a week or so. I have found that I can lose any weight I gained this way and it helps me to get back into the right frame of mind to return to healthy eating.

I lost about 4lbs in one week eating virtually nothing but porridge (Oats So Simple sachets in different flavours); which was one pound extra than I gained when fell off the wagon for a week!

Also, as the research shows – regular exercise alongside calorie reduction has the most chance of success in keeping the weight off. You don’t have to join a gym – you can exercise at home with a few inexpensive pieces of equipment like me.

Research may prove that overall diets fail – but if you take the right approach you can still be a winner!


Chatman, A et al (2007) Medicare’s Search for Effective Obesity Treatments: Diets Are Not the Answer; American Psychologist; Vol 62; No.3; pp 220-233

Connor S (2010) Junk Food Could Be Addictive Like Heroin; The Independent; March 29

Delbridge, E et al (2011) Long Term Persistence of Hormonal Adaptions to Weight Loss; New England Journal of Medicine; Vol 365; pp 1597-1604

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