The amount of a hunger-fighting hormone can be increased by eating a higher protein diet, researchers report in the September issue of the journal Cell Metabolism, published by Cell Press. The hormone, known as peptide YY (PYY), was earlier found by the researchers to reduce food intake by a third in both normal-weight and obese people when given by injection.
"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 loss," said Medical Research Council clinician scientist Rachel Batterham of University College London, who led the new study.
Scientists have known that high-protein content meals make people feel more full and reduce food intake, resulting in improvements in weight loss and weight loss maintenance. However, the mechanism responsible remained elusive.
In a study in normal-weight and obese people, the researchers now show that enhanced-protein meals stimulate greater release of PYY than either high-fat or high-carbohydrate meals and result in a greater reduction of hunger.
Further investigation in mice supported the human study results. High-protein diets reduced the number of calories animals consumed and increased their PYY levels. Mice fed a high-protein diet also gained less weight and produced more PYY than animals that ate the usual amount of protein, they found.
In addition, the researchers found that genetically modified mice unable to produce PYY ate more and became markedly obese. The genetically modified mice were also resistant to the beneficial effects of a high-protein diet, the researchers reported, demonstrating a direct connection between protein and PYY.
When the researchers treated those hormone-deficient mice with PYY, the animals lost weight.
"The findings show that PYY deficiency can cause obesity and that PYY appears to mediate the beneficial effects of increased-protein content diets
Contact: Heidi Hardman