Physical activity and weight management: building the case for exercise.

Exercise interventions are powerful tools for helping many patient populations. For those who need to manage their weight, an exercise program combined with diet modification may be key to losing weight and keeping it off. Many patients who are already at healthy weights find that physical activity helps to prevent weight gain. The good news is that accumulating frequent short bouts of moderately intense activity can be as effective as performing longer exercise sessions less often. Aerobic exercise alone may not be enough to preserve lean muscle mass when weight is lost, but incorporating resistance exercise may prevent reductions in resting metabolic rate and lean body mass.