Weight loss occurs in a person who reduces intake of calories in his diet and or increases energy expenditure through physical exercise.

"What we found was that it did not matter whether a reduction in calories was achieved through diet or burned everyday through exercise," Dr. Leanne Redman of the Pennington Biomedical Research Center in Baton Rouge, Louisiana.

In the 6-month study of thirty-five overweight but otherwise healthy adults, 12 were assigned to reduce their calorie intake by 25 percent.   12 were assigned to diet plus exercise, reducing calorie intake by 12.5 percent and increasing their exercise by 12.5 percent.   The remaining 11 were not asked to change any thing in terms of diet and physical activity.

Redman and team found that both the diet group and diet plus exercise group experienced the same amount of weight loss. They lost 10 percent of their body weight, 24 percent of their fat mass and 27 percent of their abdominal "visceral" fat - the risky fat linked to heart disease.

The results suggest that to shed pounds, one does not need to do both dieting and exercising.   Dieting alone can be sufficient.

But the authors said that exercise can also improve aerobic fitness and reduce the risk of heart disease, diabetes and certain types of cancer in addition to weight loss.

The researchers also found that exercise helps weight loss across the whole body. One can't lose weight in a specific spot by doing physical exercise.

"Our study then would indicate that weight loss cannot override the way in which any individual stores fat. Perhaps an apple will always be an apple, and a pear, a pear," Redman was quoted by Reuters as concluding.

A scientist affiliated with foodconsumer.org comments that people should not count on exercise to shed pounds.    The best way to control weight is to control intake of calories.

He also suggests that calorie control does not mean you have to control your appetite.   Instead, you have to decide what to eat and then eat whatever amount you want to to satisfy your appetite.

To achieve such a goal, one might increase intake of plant derived foods and reduce intake of animal derived foods.   When one eats plant based foods, it is very hard for most people to gain weight no matter how much he eats.