The Stress, Eating and Exercise Equation
Did you know that researchers are keenly interested in how stress influences eating behaviors and leads to obesity? In fact, a substantial amount of scientific research has been committed to unraveling this complex question. What does it say, and how can it help you stay healthy? Here are some insights on how stress impacts eating and what can help, from Maria-Victoria Montes, who graduated from the University of New Mexico, Albuquerque (UNM), with an exercise science degree and is entering physical therapy graduate school, and Len Kravitz, PhD, the program coordinator of exercise science and a researcher at UNM.
Chronic Stress and Weight Gain
With chronic stress, the hypothalamus (the central control station for stress) directs the pituitary gland to send a signaling message hormone (the adrenocorticotrophic hormone, or ACTH) to the adrenal cortex. ACTH triggers the release of the hormone cortisol (Adam & Epel 2007). This reaction is referred to as the hypothalamic-pituitary-adrenocortical (HPA) axis.
If the chronic stress (real or perceived) is of sufficient intensity and duration, the HPA does not wind down (as it should), resulting in prolonged elevation of cortisol levels. Thus, chronic stress leads to daily increases of cortisol secretion. Cortisol can stimulate appetite during the intermittent recovery periods that occur while you are experiencing chronic stress. Cortisol (with the help of slightly elevated insulin levels) has also been shown to activate lipoprotein lipase, the enzyme that facilitates the deposition of fat (Björntorp 2001).
Additionally, chronic stress is associated with emotional changes that can include increases in anxiety, apathy and depression (Torres & Nowson 2007). These changes may lead to much higher consumption of food.
The Effect of Exercise on Stress
The good news is that exercise can help with chronic stress. The Physical Activity Guidelines Advisory Committee Report, 2008, published by the U.S. Department of Health and Human Services, concluded that physical activity can protect against feelings of distress, defend against symptoms of anxiety, guard against depressive symptoms and the development of major depressive disorder and enhance psychological well-being.
The report said that between 1995 and 2008, more than 30 studies—involving more than 175,000 people—were conducted in areas related to stress. The findings show that exercise decreases stress levels and increases feelings of well-being. Dunn and Jewell (2010) add that exercise bouts of 30 minutes (but not longer than 60 minutes) appear to have the best “stress-reducing” benefits. There does not appear to be a different impact based on the type of exercise (e.g., running, swimming, cycling, elliptical training, etc.). As to exercise intensity, the report indicates that (with regular participation) moderate to vigorous physical activity reduces stress better than low-intensity activity.
In addition to exercise, mind-body techniques such as meditation, progressive muscle relaxation and visualization can help reduce stress (Stoppler 2008).
Listening to music can also help. Luskin et al. (1998) propose that music has the power to calm, soothe and inspire. It can directly affect physiological factors such as heart rate and blood pressure and has been shown to be effective in treating anxiety, stress and depression.
Adam, T.C., & Epel, E.S. 2007. Stress, eating and the reward system. Physiology and Behavior, 91, 449–58.
Björntorp, P. 2001. Do stress reactions cause abdominal obesity and comorbidities? Obesity Reviews, 2 (2), 73–86.
Dunn, A.L., & Jewell, J.S. 2010. The effect of exercise on mental health. Current Sports Medicine Reports, 9 (4), 202–207.
Luskin, F.M., et al. 1998. A review of mind-body therapies in the treatment of cardiovascular disease. Part 1: Implications for the elderly. Alternative Therapies, 4 (3), 46–61.
Stoppler, M.C. 2008. Stress management techniques. MedicineNet.com. www.medicinenet.com/stress_management_techniques/article.htm; retrieved Oct. 29, 2010.
U.S. Department of Health and Human Services. 2008. Part G, section 8: Mental health. Physical Activity Guidelines Advisory Committee Report. Washington, DC. www.health.gov/PAguidelines/Report/G8_mentalhealth.aspx.