It's age-old advice: to lose weight, get active. Any health expert will agree that while obesity may have many causes, the best way to prevent it is to expend at least as much energy as you consume. And if you still need convincing, their case is supported by the numbers: With funding from the National Heart, Lung, and Blood Institute, researchers conducted a 10-year study of the eating and exercising habits of more than 2,200 adolescent girls in the U.S. Each year, researchers also measured the girls' body-mass index, or BMI, a gauge of their body weight in relation to height.

The study found that between the ages of 9 and 19, the girls' levels of physical activity dropped off significantly. At the same time, their rates of overweight and obesity doubled, despite the fact that the eating habits reported by the girls did not  explain the weight gain. Authors of the study (published at thelancet.com) offer easy advice: To stave off adolescent weight gain, teen girls should boost their exercise routines with 2.5 hours a week of brisk walking.

From our archive:
12/27/2004  The Year of Obesity
06/07/2004  America's Obesity Crisis