Study confirms protein's role in fullness

High-protein diets have been increasing in popularity in recent years, with many believing that eating protein-rich meals leads to increased feelings of fullness. However, this idea has not been tested on a large scale. Now, a systematic review of the evidence on the effect of protein intake on perceived fullness has confirmed the theory, finding that protein does, in fact, make us feel fuller.

“A good deal of evidence suggests that protein activates satiety hormone release and so should be most strongly tied with fullness ratings,” said lead investigator Richard D Mattes, MPH, PhD, RD, Distinguished Professor, Department of Nutrition Science, Director of Public Health, and Director of the Ingestive Behavior Research Center at Purdue University, “but individual studies are often conducted in small populations or with different approaches that can make interpretation of results challenging. Our study combined multiple experiments to confirm the presence of an effect.”

However, the authors of the study, which was published in the Journal of the Academy of Nutrition and Dietetics, caution that while protein may help dieters feel fuller, it is by no means a magic bullet. “Feelings like hunger and fullness are not the only factors that influence intake. We often eat for other reasons. Anyone who has ever felt too full to finish their meal but has room for dessert knows this all too well,” explained Dr Mattes.

The study also did not determine the exact amount of protein needed to prolong fullness or the optimum time of day to consume protein. The researchers suggest that people looking to moderate their energy intake by enhancing the sensation of fullness might consider a moderate increment in protein consumption as a first step.

“Though this study did not specifically evaluate dieters, feeling fuller could help to reduce food intake, an important factor when dieting,” concluded Dr Mattes. “If these effects are sustained over the long term — and our study only looked at short-term effects — increased protein intake may aid in the loss or maintenance of body weight.”