Cell Metab. 2006 Sep.
Critical role for peptide YY in protein-mediated satiation and body-weight regulation.
Batterham RL, Heffron H, Kapoor S, Chivers JE, Chandarana K, Herzog H, Le Roux CW, Thomas EL, Bell JD, Withers DJ.
Centre for Diabetes and Endocrinology, Department of Medicine, University College London, United Kingdom.
[ PubMed ]

Abstract: Dietary protein enhances satiety and promotes weight loss, but the mechanisms by which appetite is affected remain unclear. We investigated the role of gut hormones, key regulators of ingestive behavior, in mediating the satiating effects of different macronutrients. In normal-weight and obese human subjects, high-protein intake induced the greatest release of the anorectic hormone peptide YY (PYY) and the most pronounced satiety. Long-term augmentation of dietary protein in mice increased plasma PYY levels, decreased food intake, and reduced adiposity. To directly determine the role of PYY in mediating the satiating effects of protein, we generated Pyy null mice, which were selectively resistant to the satiating and weight-reducing effects of protein and developed marked obesity that was reversed by exogenous PYY treatment. Our findings suggest that modulating the release of endogenous satiety factors, such as PYY, through alteration of specific diet constituents could provide a rational therapy for obesity.

(09/05/06 - WebMD) When released in the gut, the hormone known as PYY reduces hunger. And high-protein foods set off PYY better than other foods, according to a study by Rachel L. Batterham, MD, of University College London, and colleagues published in the journal Cell Metabolism.

Recent studies suggest PYY is part of the solution to obesity. Compared with a normal-weight person, for example, an obese person has to eat twice as many calories to trigger PYY. "We've now found that increasing the protein content of the diet augments the body's own PYY, helping to reduce hunger and aid weight lossweight loss," said Batterham says.

Batterham's team first looked at what kind of food best satisfies hunger. They studied nine obese men and 10 normal-weight men. After brief fasts, the men ate different meals. Each of the meals - a high-protein meal, a high-fat meal, and a high-carbohydrate meal - had the same number of calories. All the men said the high-protein meal best satisfied their hunger. Interestingly, the normal-weight men found the high-fat meal more satisfying than the high-carb meal, while the obese men did not. Measurements showed the high-protein meal triggered the most PYY in all of the men. In the normal-weight men - but not the obese men - the high-fat meal triggered more PYY than the high-carb meal.

Batterham's team then genetically engineered a mouse strain that did not have the PYY gene. These mice ate huge amounts of food and quickly became obese. Normally, obese mice fed a high-protein diet will eat less and lose weight. But a high-protein diet didn't help the PYY-defective mice lose weight - unless they also got PYY treatments.

Why does protein trigger PYY and satisfy hunger so well? It's not entirely clear, but Batterham and colleagues suggest evolution is the reason. The prehistoric humans whose genes we inherit had a different diet than we do. They got 19% to 35% of their energy from protein and 22% to 40% from carbs. Our modern diet gets 49% of its energy from carbs and only 16% from protein.

"One potential weight loss strategy is therefore to increase the satiating power of the diet and promote weight loss through the addition of dietary protein - harnessing our own satiety system," Batterham says. "Such a diet is perhaps more typical to that of our hunter-gatherer ancestors."

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