A high-protein diet can make regular exercise more effective for women trying to lose weight _ helping to build muscle while trimming body fat, a small study suggests.
In a four-month period, the protein-rich diet along with exercise significantly reduced abdominal fat and triglycerides, risk factors for heart disease, according to findings published in the August issue of the Journal of Nutrition.
"People thinking about doing exercise want a return on that investment," said Donald K. Layman, a professor of nutrition at the University of Illinois' Urbana-Champaign campus, who led the study. "Our way of looking at it is the protein-rich diet basically boosts the benefit of doing exercise."
The study was largely funded by beef and dairy interests. A nutritionist not involved with the study said that what the research really showed is that exercise is important for losing fat and preserving muscle.
"That's exactly what we want to have happen in a weight reduction diet," said Roberta Anding, a clinical dietitian at the Baylor University College of Medicine who works with the Houston Texans football team.
She cautioned that diets should not be protein-dominant and noted that the average American eats "more protein than we need to begin with."
Many high-protein diets, such as the Atkins plan, have fallen from favor with consumers in recent months. Layman's diet for the study was lower in fat and called for more fruits and vegetables than the Atkins diet.
The research was funded by the Illinois Council on Food and Agricultural Research, the National Cattlemen's Beef Association, Kraft Foods and the Beef Board.
Forty-eight women took part in the study, eating about 1,700 calories per day. Half ate a diet rich in meat and dairy while half ate a diet that contained more complex carbohydrates, such as rice or pasta.
Each group was then split between women who were asked to walk 30 minutes a day, five days a week, and women who were required to walk at least that much and participate in two 30-minute weightlifting sessions per week.
The low-exercise group was voluntary and averaged less than 100 minutes per week. The other group was supervised and averaged more than 200 minutes of exercise per week, Layman said.
All the women who exercised at least 200 minutes per week lost about the same amount of weight whether they ate a high-protein or a high-carb diet. But almost all the weight lost by those who ate the protein diet was fat, while almost one-third of the weight lost by those on the high-carb diet was muscle.
While the research involved only women, there is no reason to believe that men would not have the same results, Layman said.
Shirley Washington swears by Layman's diet. Even though she is still overweight at 267 pounds (120 kilograms), she has lost 90 pounds (40 kilograms) while following it.
"It's been really easy," said Washington, a 55-year-old Chicago grandmother. "I tell anyone if you can't make it on this eating plan, you can't make it.",. AP reported.