Unraveling cysteine deficiency-associated rapid weight loss [liver II]

Forty percent of the US population and 1 in 6 individuals worldwide are obese, with the incidence surging globally1,2. Various dietary interventions, including carbohydrate, fat and more recently amino acid restriction, have been explored to combat this epidemic3-6. We investigated the impact of removing individual amino acids on the weight profiles of mice. Here, we show that conditional cysteine restriction resulted in the most dramatic weight loss when compared to essential amino acid restriction, amounting to 30% within one week, which was readily reversed. We found that cysteine deficiency activated the integrated stress response and oxidative stress response, which amplify each other, leading to the induction of GDF15 and FGF21, which partly explained the phenotype7-9. Surprisingly, we observed lower tissue coenzyme A (CoA), which has been considered to be extremely stable10, resulting in reduced mitochondrial functionality and metabolic rewiring. This results in energetically inefficient anaerobic glycolysis and defective TCA cycle, with sustained urinary excretion of pyruvate, orotate, citrate, α-ketoglutarate, nitrogen rich compounds, and amino acids In summary, our investigation reveals that cysteine restriction, by depleting GSH and CoA, exerts a maximal impact on weight loss, metabolism, and stress signaling compared to other amino acid restrictions. These findings suggest novel strategies for addressing a range of metabolic diseases and the growing obesity crisis.