Because slow walking does not contribute to cardiovascular fitness, obese people also should adopt some form of vigorous low-impact exercise like swimming or cycling.

Ray Browning, a doctoral student at the University of Colorado at Boulder, said that his studies show that the obese burn more calories per mile when they adopt a speed below their normal pace. He said that slow walking as an additional benefit -- placing less stress on knee joints.

Browning and his colleagues found, to their surprise, that the number of calories burned per pound of body weight was the same for the obese and subjects of normal weight. Some researchers had believed that the obese would have to use an awkward stride, burning more calories.

Does Not Contribute to Cardiovascular Fitness

The subjects probably are unwittingly altering their posture and walking with straighter legs, conserving calories in the process, Browning said.

Because slow walking does not contribute to cardiovascular fitness, Browning recommended that the obese also adopt some form of vigorous low-impact exercise like swimming or cycling.

The study was presented at the June meeting of the American College of Sports Medicine and published in the journal Obesity Research.