To evaluate the functional role of αB-crystallin/HspB2 in diet-induced obesity and diabetes, we placed αB-crystallin/HspB2-deficient and littermate controls (wild-type, WT) on normal chow or high fat diets and monitored weight and metabolic parameters over time. The gene discussed is HSPB2; the disease is obesity due to melanocortin 4 receptor deficiency.