A low protein, high carbohydrate diet may be the most effective for stimulating a hormone with life-extending and obesity-fighting benefits, according to the latest Australian research.

The study, published in the journal Cell Metabolism, paints a clearer picture of the role of Fibroblast Growth Factor 21 (FGF21), the so-called fountain of youth hormone produced primarily in the liver.

Previous studies have found that FGF21 plays a role in curbing appetite, moderating metabolism, improving the immune system and extending lifespan. It is also currently being used as a therapeutic target for diabetes but little is known about how this hormone is triggered and released in the body.

Now researchers at the University of Sydney’s Charles Perkins Centre have found that diets high in carbohydrate and low in protein are the best for boosting levels of FGF21 in mice.

"Despite the popularity of high protein Palaeo diets, our research suggests the exact opposite may be best for us as we age - that a low protein, high carbohydrate diet was the most beneficial for late life health and longevity," says lead author Samantha Solon-Biet.

"The nutritional context in which FGF21 is most elevated is dependent on the balance of protein to carbohydrate, and this balance was also shown to be important in how this hormone helps to mediate protein hunger."

These latest findings take researchers one step closer to understanding how FGF21 works and how to use it to help people live longer and healthier lives.

The study tested 25 diets that varied in protein, carbohydrate, fat and energy content on mice.

The research was conducted in collaboration with the ANZAC Research Institute, Macquarie University, EWOS Innovation in Norway and the Pennington Biomedical Research Centre in Louisiana.

This article was originally published by Business Insider.

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