How Stress Affects Appetite
Do you tend to overeat during periods of stressful events or do you lose your appetite? The hormones released in response to stress seem to counteract each other. Corticotrophin-Releasing Factor (CRF) controls release of the major glucocorticoid cortisol via ACTH, stimulates the sympathetic nervous system, increases vigilance and suppresses appetite. Cortisol (a longer-lasting hormone in the bloodstream) appears to stimulate appetite, increase the activity of the ob gene, increase leptin levels in the bloodstream and yet decrease the efficacy of leptin.
In the book “Why Zebras Don’t Get Ulcers”, Robert Sapolsky, a Professor of Neuroscience at Stanford University, speculates that the opposite effects of CRF and glucocorticoids on appetite are modulated by the timing and duration of the involved stressor. CRF exposure occurs during the actual stressful event, so if it is short-lived, appetite may be stimulated because of the relatively minute burst of CRF compared to the longer duration of cortisol in the bloodstream. However, if the stressor is chronically persistent, the levels of cortisol as well as CRF will likely be elevated, leading to the blunting of appetite. Sapolsky reasons that there are probably many complex, individual differences in how people respond due to the amounts of hormones secreted, how strongly the hunger center is influenced, and so on. A zebra, running across the field to escape a charging lion, is doing what comes naturally for survival. If lucky, the zebra finds a hiding place and return to “normal”, digesting the next meal, etc., while many people continue “running” their sympathetic nerves into the ground in response to perceived and real psychological stressors. A chronically stimulated sympathetic nervous system is not primed to digest well nor seems to know how to eat well.
Theresa A. Tsingis, D.C., M.S.
Lamorinda Nutrition
89 Davis Rd, #180, Orinda, CA 94563
Phone: 925.283.Well (9355)