Is dieting or exercise better for weight loss?

It’s a bit complicated, but basically, it’s the net calorie deficit – expending more energy than you consume – that counts, said Eric Ravussin, a physiologist at the Pennington Biomedical Research Center in Baton Rouge, La.
In a small, randomized, controlled clinical trial, Ravussin divided three dozen overweight but healthy men and women into three groups. One group reduced their calorie intake by 25 percent. Another group cut calories by half as much (12.5 percent) while increasing energy output through exercise by 12.5 percent; and the third group made no diet or exercise changes.