Exercise is a valuable element of a weight loss program. Although exercise alone leads to only modest weight loss, and at a slower rate than calorie restriction, combining exercise with diet results in greater losses of body weight and fat than dieting alone. But what about your exercise program once you've achieved your weight goal? Johns Hopkins reviews that data to answer this important question.

Exercise is especially important for weight loss maintenance, which is harder to sustain than losing weight in the first place. And adding exercise to calorie restriction makes the dietary changes easier because they need not be as drastic. It is easy to see why this is so. To lose one pound per week requires a deficit of about 500 calories a day. By adding a half hour of moderate to vigorous exercise each day (enough to burn 250 calories), you can reduce the calorie restriction to a more manageable 250 calories daily.

But the good news is that high levels of exercise are not need to maintain weight loss – this according to a study published in the journal Obesity (Volume 15, page 1226). Exercising at a moderate intensity for an hour or more on most days of the week is generally recommended to maintain weight loss. However, a study from the University of Alabama at Birmingham suggests that a high level of physical activity isn't the only route to successful weight maintenance.

Eighty-nine participants in the university's Eat Right weight-loss program were evaluated a year after they completed the program. Eighty percent of the participants had maintained their weight loss (regained less than 5% of their ending body weight). The researchers found that the maintainers consumed 384 fewer calories per day on average than the participants who regained their weight. They also tended to eat more low-energy density foods, such as low-calorie but filling fruits and vegetables, than the regainers.

However, no significant differences were noted in the amount of exercise engaged in by the maintainers vs. the regainers -- although there was a suggestion that subjects who exercised more regained less weight than those who exercised just a little or not at all.

The bottom line: While exercise is recommended to maintain a weight loss, you may be able to get away with more modest (and doable) amounts than typically advised if you eat a low-calorie diet.