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Activation of tissue-resident myeloid cells in the brain, known as microglia, is thought to drive obesity-associated hypothalamic dysfunction. The authors of this Perspective present a more nuanced view of microglia, echoing lessons learned from the field of adipose macrophage biology: instead of simply responding to diet-induced damage, microglia are proposed to act as nutrient and environmental sensors that regulate hypothalamic physiology, a role that, if hijacked by chronic overnutrition, can produce disease.