Less protein intake may lead to more body fat, a new study suggests.

Researchers studied three types of diets with different protein content levels to determine how protein influenced weight gain and body fat. According to the researchers, led by Dr. George Bray of the Pennington Biomedical Research Center in Louisiana, the findings could have significant implications on fighting obesity.

The study observed 25 people between the ages of 18 and 35 who were made to undergo the three types of diet -- low protein, normal protein, and high protein -- for eight weeks. All the three diets had the same amount of carbohydrates and fat.

The participants, whose meals were carefully controlled, were purposely overfed by roughly 40 percent more than what they were previously eating, during the initial phase of the study. All gained weight, but those in the low-protein diet lost 2.2 pounds of muscle mass, while those in the normal and high protein groups gained muscle mass during the overeating period.

The researchers discovered that while all three groups gained body fat, in the low-protein diet, more than 90 percent of excess calories were stored in the body as fat as compared to the normal and high-protein groups that had about 50 percent of the extra calories stored as fat.

A substantial increase in the resting energy expenditure or how many calories the body burns while at rest, was also observed in the normal and high-protein groups, while there was significant change in the low-protein group. The fitter a person is, the more muscle mass he or she has, and the higher the resting energy expenditure.

"Most people are overeating and for those people who are, they need to pay attention to what they are putting into their mouths," said Leanne Redman, an assistant professor of endocrinology at Pennington Biomedical Research Cente, study co-author.

"If you overeat a high-fat, low-protein diet, you may gain weight at a lower rate, but you are gaining more fat and losing more muscle," she said.

The study was published in the Journal of the American Medical Association.