Nutrition and the stress response
We've all heard that we should avoid foods that are high in fat. But now we may have a new reason for doing so. Research at the University of Calgary has found that a single high-fat meal can elevate your stress response.
"We were interested in the effects of different types of meals on cardiovascular responses to stress," says Dr. Tavis Campbell, assistant professor in the Department of Psychology at the University of Calgary. "The idea is that exaggerated or prolonged responses to stress are associated with the development of sustained high blood pressure."
Dr. Campbell set out to examine the effects of high-fat meals on the stress response. Study participants came to the lab on two separate occasions following a night of fasting. One day they ate high-fat breakfasts; within a week the same participants ate low-fat breakfasts. (In order to keep the calorie and sodium levels equal, the low-fat meal contained higher sugar and carbohydrate content to replace the fat content.) Dr. Campbell emphasizes that the study did not examine a healthy alternative breakfast, but only studied the effects of the high-fat vs. low-fat meals.
After eating each meal, participants rested for two hours, then performed a series of standardized stressor tests including taking a math test, immersing their hands in icewater, experiencing the uncomfortable pressure of inflated blood pressure cuffs on their arms, and speaking to a group about emotionally provocative events. The investigators recorded several cardiovascular measures including blood pressure, heart rate, and vascular resistance (the resistance that must be overcome to push blood through the circulatory system).
After consuming the high-fat meal, participants demonstrated exaggerated stress responses to physical and mental stress. Blood pressure and vascular resistance responses were 50% higher than after the low-fat meal. "These were striking effects after only one meal," notes Dr. Campbell.
Dr. Campbell sees this work as part of other research efforts to combat obesity and the health conditions that go with it, an emerging field for psychologists in Canada. "When we think about what drives chronic illness, the major contributors are behaviour and lifestyle choices," he explains. "Look at the major killers: More than fifty percent of cancers can be explained by health behaviours such as smoking and diet. Cardiovascular disease is driven primarily by overweight, obesity, and lack of exercise. Psychologists are experts in behaviour change. We can play a role in prevention."