CBSN

Study Explains U.S. Obesity

Many of the more than two-thirds of U.S. adults fighting the battle of the bulge could fail because they're cutting calories or exercising but not doing both, a nationwide survey found.

In fact, 35 percent of men and 40 percent of women who said they're trying to lose weight are not counting calories at all, according to a recent report Journal of the American Medical Association. Instead, they're eating less fat, but may be consuming as many or more calories from lower-fat foods, researchers said.

Even those who are combining exercise and calorie reduction often aren't exercising enough, researchers said. Only 42 percent of men and 37 percent of women trying to lose weight meet federal guidelines that call for at least 150 minutes of exercise each week.

The findings could help explain why obesity is increasing even though Americans spend $33 billion a year on weight loss products and services, said lead author Dr. Mary K. Serdula, a medical epidemiologist in the federal Centers for Disease Control and Prevention's Division of Nutrition and Physical Activity.

"It is a combination of factors," said Serdula. "We're more likely to eat out, (eat)snack foods, and physical activity is not built into our daily life."

The survey results from more than 107,000 men and women in 49 states and the District of Columbia were analyzed by researchers from the National Center for Chronic Disease Prevention and Health Promotion, an arm of the CDC.

Serdula said she was surprised that only 21.5 percent of men and 19.4 percent of women trying to lose weight reported following federal guidelines for both exercise and calorie reduction. And she said the recommendations also are important for people who are not overweight but are trying to prevent weight gain.

Reducing fat intake is important and can be a good way to automatically reduce calories as long as dieters are careful not to consume more calories overall, Serdula said. She said guidelines recommend people get 30 percent or fewer of their calories from fat and eat at least five servings each of fruits and vegetables daily.

"It is important for persons consuming no-fat or fat-free foods to check out the labels to see how many calories are in (the food)," she said. "If people feel reducing fat is synonymous with reducing calories, they have a tendency to reward themselves" with sweets.