There are many commonly held fallacies about weight loss, but none seems to do more harm than the notion that exercise is responsible for the lion's share of weight management. While exercise does burn calories, and if you burn more calories you should lose weight, but unfortunately, it's not that simple.

Researchers have found that to lose a pound of weight each week would require runners to travel the same distance of a marathon, 26.2 miles to burn the equivalent of losing one pound. Unfortunately, most runners feel the need for a reward for running that offsets the positive effects of the exercise.

Real-world studies of exercise and effect weight loss are inconclusive. A 2007 study published in the journal Obesity instructed 196 men and women to exercise an hour a day, six days a week, for a year. Researchers weren't just telling people to exercise; they were supervising them and instructing them as well.

Only seven of the participants dropped out before the year's end with men averaging over six hours of weekly exercise and women almost five hours. Just how effective was the the 320 hours of exercise for the men and the 254 hours for the women? Men lost, on average, 3.5 pounds, and women, 2.6. That translates to 91.5 hours of exercise per pound lost. Not encouraging at all.

The notion that exercise alone will generate weight loss is a dangerous one. For some people, it may effectively discourage exercise when results aren't seen immediately on scales. For the media and entertainment industries, it often leads to the perpetuation of the "people-with-a-lack-of-will-power" label. For the food processors, it allows an embrace of exercise by means of sponsorship and marketing, which, in turn, helps companies deflect product blame and forestall industry-unfriendly legislation.