Studies reveal how the right combination of macronutrients may facilitate weight loss
With more than two-thirds of adults determined to be overweight, guidelines help achieve and maintain a healthy body weight, a key health concern. New research is helping to explain causes and possible solutions for the near-epidemic weight gain in Americans over the last few decades.
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n part, the solution to this growing health concern may lie in findings that were published in two other recent studies. In the first study, researchers were interested to learn why low-carbohydrate diets help subjects to lose weight. What they found is that a macronutrient mixture, namely the high-protein, not low-carbohydrate content of popular diets like Atkins, aid in people losing weight. The reason appears to be that protein is more satiating and energy-burning than either carbohydrate or fat.
In the study, researchers varied the amounts of protein and fat that study participants consumed, while keeping carbohydrate intake constant. The study excluded individuals with a body mass index of 30 or higher; those who did aerobic exercise for more than 30 minutes, three times a week; those who used tobacco, alcohol, had diabetes or any other medical condition.
What the researchers found is that people became more satiated on a high-protein (30%) diet. The study results could not be explained by the hunger hormone ghrelin which increased or the satiety hormone leptin which decreased during this phase of the research.
In a second study that was published in January of 2006, researchers wanted to test the hypothesis that a low-fat, high-carbohydrate diet - a diet which is promoted by organizations such as the American Cancer Society and American Heart Association - contributed to the rise in obesity over the past several decades.
Not surprisingly, this is a notion that has been purported by advocates of low-carb diets like Atkins and The South Beach Diet.The low-fat study was part of the Women's Health Initiative which followed about 48,000 postmenopausal women for an average of 7.5 years. About 40% of the women in the study were assigned to a low-fat diet with the remaining 60% of the women assigned to a control group. Initially, both sets of women consumed at least 32% of their daily caloric intake from fat. Women in the low-fat group were told to consume no more than 20% of their daily caloric intake from fat. These women also participated in a series of group sessions designed to reduce dietary fat intake while increasing complex carbohydrate intake. The control group was not given any specific dietary restrictions but received a copy of the Dietary Guidelines for Americans. Neither group was instructed to exercise or to restrict their caloric intake.
During the first year of the study, women on the low-fat diet lost an average of 4.8 pounds compared to the control group. In addition, many of the women maintained their weight loss over the next several years. Based on these results, the researchers concluded that a low-fat diet may prevent the tendency for women to gain weight during their postmenopausal years. Also concluded was that a low-fat diet paired with complex carbohydrates such as fruits, vegetables and whole grains has not been a contributing factor to the rising rate of obesity in this country.
For the majority of healthcare professionals who are involved in providing care to an increasingly obese patient population, these two studies provide direction for weight management in these patients. Based on these findings, encouraging patients to consume 30% of their calories from protein, 20% from fat and 50% from complex carbohydrates seems prudent. Guidance should be based on helping patients to make quality choices within each macronutrient group, with emphasis on lean sources of protein, unsaturated fats and complex carbohydrates from fruits and vegetables.