Protein diet plus exercise equals more weight loss

Women who follow a high-protein, low-carbohydrate diet may lose more weight and body fat, particularly when they engage in regular exercise, than those whose diets are low in protein and high in carbohydrates, a team of Illinois researchers reports.

"A protein-rich diet, restricting carbohydrates, is a very good way to lose weight," said study author Dr. Donald K. Layman. "It definitely enhances the benefits of doing exercise."

Yet, both a high-protein and a high-carbohydrate diet are effective for women who desire to reduce their cholesterol level or otherwise improve their blood lipid profile, the report indicates.

A growing body of research points to the benefits of low-calorie diets that are low in carbohydrates and high in protein. Regular exercise is also known to be both a necessary component of any effective weight loss strategy and key to the maintenance of that weight loss. Yet, few researchers have examined the combined role of a high-protein, low-carbohydrate diet and exercise in weight loss and body composition.

Carbohydrates are one of the main dietary components. This category of foods includes sugars, starches, and fiber.

The primary function of carbohydrates is to provide energy for the body, especially the brain and the nervous system. Your liver breaks down carbohydrates into glucose (blood sugar), which is used for energy by the body.

To investigate, Layman, a nutrition professor at the University of Illinois, in Urbana, and his team studied 48 women, aged 40 - 56 years. The women were randomly assigned to one of four groups: a high-protein diet group, a high-protein diet group that exercised, a high-carbohydrate group and a high-carbohydrate group that exercised.

The diets were equal in total energy, and were both "nutritionally sound," the researcher noted, allowing the women to consume recommended amounts of fruits, vegetables and dairy products, while controlling their servings of protein and carbohydrates, respectively.

Those who exercised were required to walk for at least 30 minutes a day for five days a week and to participate in a resistance training program twice a week, using weight machines.

At the end of the 16-week study period, women in all four groups lost a significant amount of weight, lost body fat and reduced their calorie intake, Layman and his team report in the Journal of Nutrition.

However, those who consumed the high-protein diet lost more body weight and total fat and less lean muscle mass than did those on the high-carbohydrate diet, the report indicates. Further, the addition of exercise, particularly to the high-protein diet, allowed women to lose even more body fat and preserve lean mass.

For example, women that consumed a high protein diet and exercised reduced their body fat by 21.4 percent, while those on the high-carbohydrate diet that did not exercise experienced a 12.8 percent drop in body fat, study findings show.