Sanchis, P.; Baech-laursen, C.; Vizueta, J.; Haytural, H.; Kurgan, N.; Persson, K. W.; Groenning, A.; Salinas, R.; Samodova-Sommer, D.; Guo, J.; Jensen, T. E.; Deshmukh, A. S.; Pedersen, B. K.; Brandt, C.

Exercise not only regulates energy expenditure but also appetite, yet the underpinnings remain unclear. We describe that increased energy intake is a defense against energy loss that depends on initial running distance and operates independently of diet and age. Running caused a rapid circadian-dependent fat remodeling leading to a decline in circulating leptin accompanied by the activation of hypothalamic neurons. We discovered that the activation of the {beta}3-adrenergic receptor drives running-induced fat loss and the lower leptin triggers energy compensation by upregulating Neuropeptide Y. Once energy compensation is achieved, running is associated with molecular changes in hypothalamic signaling related to appetite and functional adaptations, such as enhanced sensitivity to hunger and satiety signals and increased responsiveness to appetite suppression induced by -Melanocyte-Stimulating Hormone. The increased food intake persisted without fat rebound beyond running in both lean and obese young mice, uncovering a new homeostatic balance in young mice.