Methods and devices are provided for activating brown adipose tissue (BAT). Generally, the methods and devices can activate BAT to increase thermogenesis, e.g., increase heat production in the patient, which over time can lead to weight loss. In one embodiment, a medical device is provided that activates BAT by electrically stimulating nerves that activate the BAT and/or electrically stimulating brown adipocytes directly, thereby increasing thermogenesis in the BAT and inducing weight loss through energy expenditure.