Two major studies from the University of Southern Denmark (published in eLife) and Yale School of Medicine (published in Nature Metabolism) converged on the same discovery.
Cutting two specific amino acids — methionine and cysteine — from mice diets triggered a 20% increase in calorie burning without any change in food intake or exercise. The mice simply generated more heat through a process called thermogenesis.
The Danish team found that diet-induced thermogenesis produced almost the same weight loss as constant exposure to 5°C cold. Professor Jan-Wilhelm Kornfeld: "They lost more weight, and it was not because they ate less or exercised more — they simply generated more heat."
The Yale study went further: mice on a high-fat diet that had cysteine removed returned to a healthy weight. Nearly all their white fat (storage fat) converted to brown fat (energy-burning fat). They were burning off calories as fast as they consumed them.
Methionine and cysteine are found in high amounts in animal proteins (meat, eggs, dairy) and in much lower amounts in plant foods (vegetables, nuts, legumes). The Yale connection came from the CALERIE-II trial — the first controlled study of calorie restriction in healthy humans — where lower cysteine levels correlated with metabolic benefits.
Source: ScienceDaily / University of Southern Denmark | Yale School of Medicine