Why high protein diets may keep you slim

A group of scientists, led by Dr Rachel Batterham (UCL Medicine, MRC Clinician Scientist), have discovered that the amount of a hunger-fighting hormone can be increased by eating a higher protein diet.

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.

The research published in the journal Cell Metabolism suggests that PYY may be the secret ingredient at work in high-protein weight-loss diets.

The team investigated the effects of different diets on hunger and circulating levels of PYY. They found that in obese and normal weight volunteers an increased protein diet resulted in the highest levels of PYY and the greatest reduction in hunger.

Further investigation in mice supported the human study results. Increased protein diets reduced the number of calories consumed, resulting in reduced body weight and adiposity whilst increasing levels of PYY.

By creating mice that cannot produce the hormone (PYY null mice), the team were able to determine the precise impact of PYY on appetite. These mice, when presented with the same amount of food as normal mice, ate more and became obese. When given a high protein diet the PYY null mice did not benefit from the diet's satiating effects.

Dr Batterham said: "To confirm the role played by PYY, we then gave the PYY back to the PYY null mice. Their food consumption went down to normal levels as did their weight. When they no longer received PYY, their food intake and weight went up again."

This work resolves an ongoing debate in the scientific community as to the role of PYY; a debate which prompted Dr Batterham to conclusively investigate the hormones role. Her experiments show that PYY plays a key role in regulating hunger and that topping it up reduces appetite.

"This research suggests that an increase in the protein content of the diet may help tackle obesity by reducing hunger. However, large scale clinical trials are needed before high protein low-fat diets can be recommended"

To find out more about Dr Batterham, or to view UCL's statement on the use
of animals in research, use the links at the bottom of this article.

Image: Dr Batterham

---

• Links:
• Dr Rachel Batterham
• Statement