Monday, June 1, 2009

Death of the Energizer Bunny


The fitness industry suffered a bit of a blow last week. A recently released study shows that exercise doesn’t boost the body’s long-lasting calorie-burning power, after all.

This is bad, right?

The ability to prime the body to burn calories even after a person stops exercising has been the fitness industry’s answer to the consumer’s hunt for the “magic pill.” We’ve been selling exercise as the gift that keeps on giving, turning the fit body into a calorie-burning Energizer Bunny.

But, if this study is right, then we’ve been wrong.

How will this affect people’s perception of exercise? Will this one study change you sell your product? For me, anyway, this study seems to have raised more questions than it’s answered.

1 comment:

Kym Wimbis said...

Hi Heather,

The article that you point to is very much consistent with my understanding of exercise's effects on resting metabolic rate (RMR).

It has been around 10 years since I have read any primary articles on the subject (but I did read quite a few as part of my post graduate studies in exercise science) but the consensus was that vigerous exercise (> 85% Vo2 max) elicited the greatest increase in RMR that would typically return to baseline levels within a few hours of ceasation of exercise.

These are intensities that average, obese or deconditioned subjects were unlikely to be able to sustain for a long enough duration to have a significant effect on weight loss.

Aerobic activity elicited a significantly greater response in overall magnitude of increase and time to return to baseline levels than resistance training (RT).

I believe that the article states the role of exercise on RMR and the usefullness of RT in weight loss quite accurately.

Most studies that recommended RT to mitigate against reductions in RMR were used in conjunction with Very Low Calorie Diets (VLCD) where there were significant losses of lean muscle mass which resulted in corresponding reductions in RMR.

In some cases (but not all) the addition RT ameloriated these losses.

On balance most studies demonstrated that diet + exercise was better than diet or exercise alone for weight loss especially in the longer term (1-5 years).

In any event I am not sure that most people's primary motivation to exercise is to increase RMR as opposed to looking and feeling better (regardless of the mechanism of action).

Those who have been 'selling' the beneficial effects of exercise on RMR as a key to weight loss have been guilty of selling the sizzle and not the steak.