Scientists compared ordinary lab mice with mice genetically engineered to lack capsaicin receptors. The guts of ordinary mice responded noticeably to a capsaicin-like drug. Those on a high-fat diet did not. In mice without capsaicin receptors, diet made no difference in these gut-level responses. Capsaicin – the chemical that gives chili peppers their kick – really does seem to be an aspirin-like drug: it has many beneficial health effects with no apparent downside. The chili effect is opening a window on some of the mysteries of how metabolism works, and perhaps treatments for overeating and obesity as well. Hot peppers tend to suppress appetite. The key is the capsaicin receptor, the protein that detects capsaicin and triggers the “hot” sensation. Capsaicin receptors in the mouth, skin, eyes and nasal passages actually do detect heat in addition to spiciness. Capsaicin receptors help signal the brain that this stretching is occurring. So you feel full, and stop eating. But obviously, some people routinely stuff themselves.
