'Biggest loser' study shows why weight keeps coming back

Keeping weight off after you have lost it is usually harder than shedding those extra kilos in the first place. But the real question is

While it's known that metabolism slows when people diet, a new research from the National Institutes of Health indicates that metabolism remains suppressed even when people regain much of the weight they lost while dieting.

The findings come from a study of contestants in 'The Biggest Loser' television series. Despite substantial weight regain in the 6 years following participation, resting metabolic rate remained at the same low level that was measured at the end of the weight loss competition.

The average rate was approximately 500 calories per day lower than expected based on individuals' body composition and age.

"Long-term weight loss requires vigilant combat against persistent metabolic adaptation that acts to proportionally counter ongoing efforts to reduce body weight," wrote the authors.

The study appears in the journal Obesity.