Little-Known Amino Acid Could Be Secret to Rapid Weight Loss

In both human trials and animal studies, lower cysteine levels sparked the transformation of white fat into heat-producing brown fat, resulting in weight loss, improved metabolism, and even reduced inflammation, the journal Nature Metabolism reported.

Cutting calories is widely recognized as a way to improve health and shed excess weight, but new research in I highlights a more specific factor: the sulfur-containing amino acid cysteine. In the study titled “Cysteine depletion triggers adipose tissue thermogenesis and weight loss,” scientists found that when participants reduced their calorie intake, cysteine levels in white fat also dropped.

Researchers at Pennington Biomedical, including Dr. Eric Ravussin and Dr. Krisztian Stadler, explored cysteine’s role in fat metabolism and discovered that its reduction promotes the conversion of white fat cells into brown fat cells. Brown fat is more metabolically active, using energy to produce heat and maintain body temperature. In animal studies, completely removing cysteine led to substantial weight loss, increased fat burning, and enhanced browning of fat cells, underscoring cysteine’s influence on metabolic processes.

“In addition to the dramatic weight loss and increase in fat burning resulting from the removal of cysteine, the amino acid is also central to redox balance and redox pathways in biology,” said Dr. Stadler, who directs the Oxidative Stress and Disease laboratory at Pennington Biomedical. “These results suggest future weight management strategies that might not rely exclusively on reducing caloric intake.”

The findings draw on data from both human and animal trials. In the human study, fat tissue samples were collected from participants who had reduced calorie intake over a year. Researchers analyzed thousands of metabolites, compounds created as the body processes food and stores energy, and found a clear drop in cysteine levels.

“Reverse translation of a human caloric restriction trial identified a new player in energy metabolism,” said Dr. Ravussin, who holds the Douglas L. Gordon Chair in Diabetes and Metabolism at Pennington Biomedical and oversees its Human Translation Physiology Lab. “Systemic cysteine depletion in mice causes weight loss with increased fat utilization and browning of adipocytes.”

The tissue samples came from participants in the CALERIE clinical trial, which recruited healthy young and middle-aged men and women who were instructed to reduce their calorie intake by an average of 14% over two years. With the reduction of cysteine, the participants also experienced subsequent weight loss, improved muscle health, and reduced inflammation.

In the animal models, researchers provided meals with reduced calories. This resulted in a 40% drop in body temperature, but regardless of the cellular stress, the animal models did not exhibit tissue damage, suggesting that protective systems may kick in when cysteine is low.

“Dr. Ravussin, Dr. Stadler, and their colleagues have made a remarkable discovery showing that cysteine regulates the transition from white to brown fat cells, opening new therapeutic avenues for treating obesity,” said Dr. John Kirwan, Executive Director of Pennington Biomedical Research Center. “I would like to congratulate this research team on uncovering this important metabolic mechanism that could eventually transform how we approach weight management interventions.”

4155/v