Stress + High-Fat Meal = Weight Gain

Women who experience one or more stressful events the day before eating a single high-fat meal may metabolize food more slowly, with the daily effect potentially adding up to as much as 11 pounds in a year. Janice K. Kiecolt-Glaser, from The Ohio State University (Ohio, USA), and colleagues enrolled 50 women, average age 53 years, who received three standardized meals on the previous day and instructed them to fast for 12 hours before reporting for their study visit.  On the day of admission, the participants completed several questionnaires to assess their depressive symptoms and physical activity and were interviewed about stressful events on the prior day. Thirty-one women reported at least one prior day stressor on one visit and 21 reported stressors at both visits. Six women reported no stressors.   The research meal consisted of eggs, turkey sausage, biscuits and gravy – roughly equivalent in calories and fat to a loaded two-patty hamburger and French fries at a fast-food restaurant. Participants were required to eat the entire meal within 20 minutes.  The control for comparison in this randomized trial was that one meal contained saturated fat and another was high in a different kind of fat: sunflower oil containing monounsaturated fat, which is associated with a variety of health benefits.  Before the meal, participants rested for 30 minutes and their energy expenditure – or calories burned by converting food to energy – was tested during that time. After they ate their meal, their metabolic rate was tested for 20 minutes of every hour for the next seven hours.   Researchers also took multiple blood samples to follow metabolic activity throughout  the post-meal day.   Testing revealed that the stressors' effects of increasing insulin had a time element: Insulin spiked soon after the high-fat meal was consumed and then decreased to roughly match insulin levels in nonstressed women after another 90 minutes.  A history of depression alone did not affect metabolic rate, but depression combined with previous stressors led to a steeper immediate rise in triglycerides after the meal.  The study author conclude that: “The cumulative 6-hour difference between one prior day stressor and no stressors translates into 435 kJ, a difference that could add almost 11 pounds per year. These findings illustrate how stress and depression alter metabolic responses to high-fat meals in ways that promote obesity.”