Normal weight adults, including those who had lost a lot of weight and kept it off, ate more often than overweight people in a new study looking at factors that may help in preventing weight gain.

Researchers following about 250 people for a year found that overweight individuals ate fewer snacks in addition to meals than people in the normal body weight range, but the overweight still took in more calories and they were less active over the course of the day.

"Most of the research has shown that people who eat more frequently have a lower weight," said lead researcher Jessica Bachman, assistant professor in the Department of Nutrition and Dietetics at Marywood University in Scranton, Pennsylvania. "But no one knows why."

In particular, Bachman told Reuters, she wanted to understand what people who have lost significant amounts of weight do to maintain their weight loss, as a first step to helping guide others in losing weight and keeping it off.

More than 60 percent of people in the United States are obese or overweight, but the relationship between the number of meals people eat each day and the ability to maintain weight loss has remained unclear, she said.

Bachman and her team analyzed data collected in two large studies sponsored by the National Institutes of Health. One looked at the eating habits of people with a body mass index (BMI), a measure of weight relative to height, between 25 and 47, which is considered overweight to obese.

The other study looked at adult men and women who were normal weight (BMI of 19-24.9), about half of whom had lost at least 13.6 kg and maintained their lower weight for more than five years.

The researchers found that, on average, the normal weight subjects ate three meals and a little over two snacks each day, whereas the overweight group averaged three meals and just over one snack a day.

Generally, though, "weight loss maintainers" consumed the fewest calories, at about 1,800 a day, compared with the normal weight and overweight subjects, who took in 1,900 and more than 2,000 calories a day, respectively.

Weight loss maintainers also were the most physically active of the three groups, Bachman said, burning off about 3,000 calories a week through exercise and other activities, compared to 2,000 calories a week among the normal weight subjects and 800 calories a week in the overweight group.

The results, published in the Journal of the American Dietetic Association, suggest that weight loss maintainers intentionally do more to keep from regaining extra pounds, Bachman said.

"It appears that being extremely physically active and eating more often helps them keep the weight off," she said. "Most commonly, they were walking at least 60 minutes a day seven days a week."

Bachman believes her study is the first to compare eating frequencies among successful weight loss maintainers, other normal weight people and those who are overweight.

She speculates that snacking might help prevent weight gain by staving off intense hunger.