A specific group of amino acids called branched-chain amino acids (BCAAs) is elevated in the blood of obese, insulin-resistant humans and rodents. A new study in mice indicates that lowering consumption of BCAAs may combat the metabolic problems that occur in diabetes and obesity. The findings are published in the Journal of Physiology.

Lead author Dr. Dudley Lamming from the University of Wisconsin-Madison, Madison, and colleagues found that lowering the consumption of BCAAs (leucine, isoleucine, and valine) improved metabolic health, even when overall calories were not reduced.

They found that feeding obese, pre-diabetic mice a low-BCAA diet promoted leanness and improved the regulation of blood sugar.

The researchers examined their weight, body composition, glucose metabolism and energy expenditure.

Importantly, mice in this study were free to eat as much of the low-BCAA food as they wanted, and thus did not experience overall calorie reduction.

Despite continuing to eat an unhealthy high-fat and high-sugar diet, mice on the low-BCAA diet still experienced an improvement in metabolic health.

“If these results can be translated to humans, it is possible that such diets, or drugs that mimic the effect of a low-BCAA diet, would be easier for people to follow and more effective than traditional calorie-counting diets,” Dr. Lamming and co-authors said.

“We hope that a low-BCAA dietary approach could be an effective way to treat or prevent metabolic syndrome, which is a group of conditions including high blood pressure, high blood sugar, abnormal cholesterol levels, and excess abdominal fat that collectively increase the risk of diabetes, heart disease, and stroke.”

The team plans to investigate whether reducing dietary BCAAs can improve the metabolic health of humans, and how the specific amino acid composition of dietary protein regulates metabolic health.

“This could help explain the wide variation seen between individuals in response to different weight-loss diets,” the scientists said.

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Nicole E. Cummings et al. Restoration of metabolic health by decreased consumption of branched-chain amino acids. Journal of Physiology, published online December 19, 2017; doi: 10.1113/JP275075