A Female-Specific Microglial Redox Program Gates Susceptibility to Obesity

Chronic consumption of energy-dense, high-fat foods persistently exposes hypothalamic circuits that govern body weight to nutrient excess, progressively altering their activity and thereby promoting obesity. Microglia, the brain resident immune cells, sense circulating lipids, but how their intracellular metabolic programs adapt to chronic dietary excess, and how this contributes to obesity risk, is unclear. Here, we reveal a sex-dependent control of calorie overload by hypothalamic microglial cells. In females, but not males, microglia engage a protective metabolic program with increased antioxidant capacity and mitochondrial network remodeling, conferring resistance to early weight gain. Over time, activation of mTORC1 signaling in microglia disrupts mitochondrial functions and dismantles this transient resilience, culminating in weight gain. These findings identify microglial mTORC1 as a sex-specific switch between resilience and vulnerability to obesity and position microglial metabolism as a tractable target for sex-informed weight control.