After many years of practicing medicine, I must admit that weight loss is one of the hardest goals for anyone to achieve, and that doctors have very little to offer in terms of prevention and really effective treatments. The main advice is always diet and exercise, but many people report that they do a lot of exercise already and still gain (or don’t lose) the excess pounds. So, does exercise really help to lose weight? The answer is actually a bit complicated.

The New York Times has an excellent review article (Weighing the Evidence on Exercise) which discusses this problem. One fascinating study found that there is an unfortunate difference between the sexes — that women have a much harder time than men in losing weight via exercise, and that the culprit is genetic:

Women’s bodies were directing them to replace the lost calories. In physiological terms, the results “are consistent with the paradigm that mechanisms to maintain body fat are more effective in women,” Braun and his colleagues wrote. In practical terms, the results are scientific proof that life is unfair. Female bodies, inspired almost certainly “by a biological need to maintain energy stores for reproduction,” Braun says, fight hard to hold on to every ounce of fat. Exercise for many women (and for some men) increases the desire to eat.

But other studies are more encouraging, showing that people who exercise more over many years have less weight gain than others. The exercise doesn’t have to be strenuous; much benefit came in the groups who do “brisk walking” for an hour a day. Plus, that brisk walking can be a simple part of your routine, and even just standing up can burn more calories than being seated all day.  That’s good news for waitresses!

The bottom line is that exercise is indeed an indispensable part of any lifestyle, and a little is always better than nothing, at any age. But don’t be disappointed if your routine isn’t melting off the pounds, especially if you’re a woman. Exercise has many benefits that extend far beyond simple weight loss.