Human body cannot be trained to maintain a higher metabolism, study suggests

"Rather than conducting a weight-loss study, our focus was to explore whether high- or low- protein diets might lead to less weight gain when consuming excess calories due to the ability of the body to burn extra energy with a high-protein diet," said Frost. "What we found was that study participants all gained similar amounts of weight regardless of diet composition; however, there was a vast difference in how the body stored the excess calories. Those who consumed normal- and high- protein diets stored 45% of the excess calories as lean tissue, or muscle mass, while those who on the low-protein diet stored 95% of the excess calories as fat."

Researchers concluded that one mechanism for weight-loss success with high-protein diets, like the Atkins Diet or the Ideal Protein Diet, could be due to an increase in our body's natural process of metabolizing food for energy following meals.

TOS recognized Frost for her research by naming her as a finalist for the Ethan Sims Young Investigator Award, an annual award given to five young researchers to cover travel expenses associated with TOS's annual meeting. All five winners presented their research during a session today in competition for the final award -- a $1,000 cash prize.

TOS says the study results reinforce the importance of energy deficit for weight loss, showing that weight loss regardless of diet composition is not possible without consuming fewer calories per day than those burned.

"High-protein diets for weight-loss or to build muscle mass can certainly be effective, but the diet composition must be maintained for dieters to continue to see and sustain results," said Steven R. Smith, TOS President. "Further, it's important to balance how many calories you eat and how many you burn on a daily basis. This concept, also known as energy balance, is vital for weight control. I congratulate Elizabeth Frost for her study, which further reinforces that it is not possible to achieve weight loss on a high-protein diet, or any diet, without burning more calories than calories consumed -- also known as energy deficit."

The study was a randomized controlled overfeeding trial of 16 healthy individuals with varied amounts of protein (low 5%, normal 15%, high 25%) for eight weeks while living in a metabolic ward. Diet-induced thermogenesis (DIT), which is one of three components for the metabolic rate, was measured over four hours by indirect calorimetry following meals. Results showed that prolonged exposure to high-protein diets does not alter DIT, and suggests that it is under acute regulation and not involved in adaptive thermogenesis, or a sustained increase in metabolism.