Study suggests high-protein diet may help maintain healthy weight

A high-protein, total replacement diet might offer a metabolic advantage compared to a diet consisting of the same number of calories, but with a lower proportion of protein, according to a new study published in The American Journal of Clinical Nutrition.

For the study, researchers compared the impact of a high-protein total diet replacement to that of a control diet, a typical North American diet, on selected components of energy metabolism. The authors recruited a group of healthy, normal-weight adults between the ages of 18 and 35 years old.  

Subjects were then randomly assigned into one of two groups: one group was fed the high-protein total diet replacement, which consisted of 35 percent carbohydrate, 40 percent protein, and 25 percent fat. The second group, the control group, was fed a diet with the same number of calories, but consisting of 55 percent carbohydrate, 15 percent protein, and 30 percent fat, a typical North American dietary pattern. Participants received the prescribed diets for a 32-hour period while inside a metabolic chamber.

Compared to the standard North American dietary pattern, the findings of this inpatient metabolic balance study revealed that the high-protein total diet replacement led to "higher energy expenditure, increased fat oxidation, and negative fat balance." The researchers said the results suggest a higher proportion of protein might lead to an increase in energy expenditure and fat oxidation compared to a diet consisting of the same number of calories, but with a lower proportion of protein as well as a higher proportion of carbohydrate or fat.

Further studies are needed to better understand the long-term effects of this dietary intervention on the physiology of both healthy and diseased population groups, the researchers said.

"Although these results are restricted to a specific population of healthy, normal-weight adults, they can help nutrition scientists and healthcare providers better understand the real physiological effects of a high-protein total diet replacement in humans,” said Carla Prado, PhD, RD, principal investigator, in a statement. “In our opinion, it is imperative to first understand the physiological impact of a high-protein total diet replacement in a healthy population group so that the effects are better translated in individuals with obesity and its related comorbidities."