The ventromedial hypothalamus (VMH) is known to regulate body weight and counter-regulatory response. However, how VMH neurons regulate lipid metabolism and energy balance remains unknown. O-linked b-D-N-acetylglucosamine modification (O-GlcNAcylation), catalyzed by O-GlcNAc transferase (OGT), is considered a cellular sensor of nutrients and hormones. Here we report that genetic ablation of OGT in VMH neurons inhibits neuronal excitability. Mice with VMH neuron-specific OGT deletion show rapid weight gain, increased adiposity, and reduced energy expenditure, without significant changes in food intake or physical activity. The obesity phenotype is associated with adipocyte hypertrophy and reduced lipolysis of white adipose tissues. In addition, OGT deletion in VMH neurons down-regulates the sympathetic activity and impairs the sympathetic innervation of white adipose tissues. These findings identify OGT in the VMH as a homeostatic setpoint that controls body weight and underscore the importance of the VMH in regulating lipid metabolism through white adipose tissue-specific innervation.