Overview

• Gene-edited mice lacking the enzyme cystathionine γ-lyase and fed a cysteine-free diet lost 30% of their body weight in one week.
• The study identifies cysteine, rather than methionine, as the key amino acid driving fat loss and metabolic benefits in sulfur-amino-acid-restricted diets.
• Cysteine depletion disrupts coenzyme A (CoA)-dependent metabolic pathways, forcing rapid fat burning and impairing energy production from carbohydrates and fats.
• The process activates integrated and oxidative stress responses, increasing the stress hormone GDF15 and preventing fat replenishment by degrading key lipid synthesis enzymes.
• Researchers aim to develop targeted approaches to mimic cysteine deprivation in humans without the risks of complete cysteine elimination.