Two colleagues of mine spent much of this year struggling to lose major amounts of weight. And both of their diets were successful, losing about 30 pounds each. That turned out to be the easy part. Now both have gained the weight back in just a few months – far less than the time it look them to lose it in the first place. And both are feeling defeated, frustrated and somewhat bewildered.
A new study in the New England Journal of Medicine could explain exactly what happened to them. Australian researchers say that the problem is not lack of willpower (although both of my colleagues admit they've cheated on their diets recently) but the hormones involved in appetite regulation.
The researchers measured hormone levels in 50 overweight or obese people who dieted for 10 weeks. The hormones were measured before the diet, after the diet was completed and then 62 weeks later.
They found interesting changes in the levels of two hormones: ghrelin, which turns on the hunger switch, and leptin, which turns off hunger. For up to a year after weight loss, there were increases in ghrelin and decreases in leptin. The researchers speculate that this probably is an evolutionary adaptation to the threat of starvation.
This provides a good explanation for why the majority of dieters regain their lost weight within five years but I think that knowing this could also help dieters plan their weight maintenance strategy.
When you lose a lot of weight, you really have to change the way you eat permanently. Return to old habits and the weight will pile on again.