"To maintain their new weight, both men and women say their fat intake was at or below the recommended limit of 30% of their diet," said Dr. Klem. "In fact, 33% of the sample reported consuming less than 20% of daily energy in the form of fat."

In addition to dietary changes needed to maintain lower weight, both male and female successful dieters regularly were involved in moderate to high intensity exercise. On average, they expended calories equivalent to walking 28 miles per week.

Participants ate regular meals, including occasional meals at restaurants. On average, they reported eating five times a day, with the majority of meals either being prepared at or eaten at home.

Among the 282 individuals who engaged in moderate intensity exercise, 48% performed stationary or road cycling, 25% aerobics, and 11% walked or ran on a treadmill.

Men participants were more likely than women to be involved in high intensity activities such as competitive sports and weight lifting.

To reduce weight, the American College of Sports Medicine (ACSM) recommends expending, during a weekly exercise program, a minimum of 1000 kilocalories. (In medicine and dietetics, the energy content of food is measured in kilocalories, which are often referred to as calories.) Seventy-one percent of the women and 79% of the men met or exceeded more than 1,000 kilocalories per week, while 50% of the women and 62% of the men exceeded 2000 kilocalories per week, listed by ACSM as an optimal physical conditioning level. For a 132-pound person, one hour of jogging burns up 540 kilocalories.

Most of the participants involved in the study reported onset of obesity in childhood. About 46% of the sample noted that they first became overweight at less than 11 years of age; over 25% became obese between the ages of 12 to 18.

A large proportion of the registry also reported a family history of overweight, with 46% having one overweight biologic parent, and almost 27% two overweight biologic parents.

To enter the study, 35% of the group (274 individuals) provided "before" and "after" weight loss photos and 42% (352) offered the names of doctors, weight loss counselors, and other individuals to verify their weight loss.

The researchers plan to follow their weight loss registry members to determine the variables that either predict continued weight maintenance, or influence the regaining of weight.

The National Weight Control Registry was developed in 1993 by Dr. James Hill at the University of Colorado, and Dr. Rena Wing at the University of Pittsburgh School of Medicine.

It's definitely possible to be overweight and fit, but it does depend on the level of fitness that you're talking about. Even if someone is overweight, they can achieve multiple benefits by starting an exercise program.