This underscores the urgent need for strategies that promote energy expenditure rather than merely suppressing food intake. Building on these findings, they mapped the circuit of Crabp1 neurons to understand how they exert their effects on energy expenditure. For example, cold exposure and physical exercise strongly activated Crabp1 neurons, driving increased energy expenditure to support thermogenesis and activity. Conversely, prolonged light exposure suppressed Crabp1 neuronal activity through the retinohypothalamic pathway, resulting in reduced energy expenditure and weight gain. More information: Ting Wang et al, Identification of a neural basis for energy expenditure in the mouse arcuate hypothalamus, Neuron (2025).