The Reason Why Running Doesn't Make You Hungry: The Secret of the Surprising Molecule 'Lac-Phe'

A recent study published in Nature Metabolism explains the reason exercise reduces appetite by showing that the exercise-induced molecule Lac-Phe directly suppresses AgRP neurons in the hypothalamus via KATP channels. When AgRP is suppressed, PVH neurons are activated, leading to decreased food intake. In mice, no behavioral abnormalities or side effects were observed, suggesting the potential for selectively suppressing appetite. Lac-Phe gained attention in 2022 as a "hunger-reducing molecule increased by exercise," and there are reports of its rise in individuals taking metformin in 2024. On social media, the prevailing cautious view is that "while understanding the mechanism is significant, its application to humans is yet to come." In drug development, there is growing anticipation for **“Exerkine (exercise factor) mimetics”** targeting KATP/AgRP, but the biggest challenge remains verifying dosage, safety, and long-term effects in humans.