Can Strength Training Protect Against the Risks of a High-Protein Diet?

A high-protein diet can benefit athletes by promoting muscle growth and strength, yet for those with a sedentary lifestyle, a high-protein diet can increase heart attack risk, have adverse effects on bone density and change the gut microbiome. Is strength training responsible for mitigating the risks of a high-protein diet? A new study, published in eLife, suggests it might be.

How much protein is too much?

Protein provides key nutrients and calories and is an essential part of our diets that contributes to growth and repair. Recommended amounts of protein change throughout our lifetimes, with most adults needing about 0.75g of protein per kilogram of bodyweight each day, or about 10% of caloric intake.

Protein intake on a high-protein diet is anything above the recommended daily allowance, but can be around 1.5g of protein per kilogram, or 20–30% of caloric intake.

The protein paradox

The lead author of the new study, Michaela Trautman from the University of Wisconsin, explains, “We know that low-protein diets … promote healthspan and lifespan in animals and that the short-term restriction of protein improves the health of metabolically unhealthy, adult humans. But this presents a paradox – if high dietary protein is so harmful, many people with high-protein diets or protein supplements would be overweight and at an increased risk of diabetes, whereas athletes with high-protein diets are among the most metabolically healthy.”

Strength training

Strength training has numerous benefits with studies suggesting that it can reduce cancer mortality, slow neurodegeneration in older adults and even rejuvenate aging skin.

In the new study, the researchers aimed to identify the impact of strength training in mice on a high-protein diet.

Two groups of mice were either fed a low-protein diet (where 7% of dietary calories came from protein) or a high-protein diet, where 36% of calories came from protein. Half of each group performed progressive resistance-based strength training in the form of pulling a cart with an increasing weight along a track three times a week over a three-month period. The other half pulled the cart with no weight added.

After three months, the researchers analyzed the body composition and weight of the mice and took measures of metabolic activity, including blood glucose.

Mice fed a high-protein diet that undertook strength training gained muscle, whereas those on a high-protein diet without the strength training gained excess fat and had impaired metabolic health compared to the mice on a low-protein diet.

Strength training has a protective effect

The research team concluded that the strength training protected the mice on the high-protein diet from fat accumulation, highlighting the importance of considering diet and exercise in our approaches to health.

Senior author Dr. Dudley Lamming says: “Our research may explain [the protein paradox], by showing that resistance exercise protects from high-protein-induced fat gain in mice. This suggests that metabolically unhealthy, sedentary individuals with a high-protein diet or protein supplements might benefit from either reducing their protein intake or more resistance exercise.”

Reference: Trautman ME, Braucher LN, Elliehausen C, et al. Resistance exercise protects mice from protein-induced fat accretion. eLife. 2023;12. doi: 10.7554/eLife.91007

This article is a rework of a press release issued by eLife. Material has been edited for length and content.