All humans require some stress to stay motivated and stimulated. Stress can be detrimental to health if it is excessive in that it exceeds normal tolerance, and/or is negative in nature. Stress can induce weight gain due to an external response (getting less sleep and eating more) or an internal response (the release of fat storage hormones in response to chronic stress, such as cortisol).
Evidence: Psychosocial Stress and Weight Gain
A recent research article published in the "American Journal of Epidemiology" studied whether various types and levels of psychosocial stressors were associated with an increase in body mass index (BMI) among adult men and women. Researchers found that stress related to work, personal relationships and finances (controlling for other factors) were independently associated with weight gain. A June 2006 article featured in "The International Journal of Obesity" examined if work stress induced weight loss in lean individuals and weight gain in overweight individuals (more than 5,500 male British civil servants). The leanest individuals at baseline (BMI less than 22 kg/m2) with high job stress and low job control lost weight by follow-up, while the heaviest individuals at baseline (BMI greater than 27 kg/m2) gained weight at follow-up. This supports the theory that those already overweight are more susceptible to stress-induced weight gain.
A Hormonal Connection
Chronic stress appears to overstimulate the hypothalamic-pituitary-adrenocortical (HPA) axis, which regulates the release of stress hormones (also fat storage hormones). Theoretically, the body needs an energy surge for "fight or flight" (even if you are not really running or moving). When hormones, such as cortisol, are released too often because of chronic environmental stress, weight gain can occur. In a 2009 study published in the journal Obesity, the dynamics of weight gain and the activity of the HPA axis in women who gained weight after a stressful event, was investigated. Twenty-four-hour urinary-free cortisol excretion rate was used as a measure of HPA-axis activity. The women were divided into two groups. Anthropometric measurements, diet and physical activity levels were similar in both groups. The stress-related obesity group had 24-hour urinary-free cortisol excretion rates that were significantly higher when compared with the non-stress-related obesity group, or the normal-weight control groups. More weight was gained in this group over a shorter period of time as well. This research supports that a biochemical or physiological factor is involved in stress-induced weight gain.
External Factors
The stress hormones have been researched, and many studies are showing a link between an increase in cortisol and weight gain or fat storage (especially around the waist). However, poor lifestyle choices, in the face of chronic stress, contribute to weight gain. It is difficult to measure how significant these are in the stress-induced obesity theory. Oftentimes, chronic stress causes fatigue, from interrupted sleep patters, for example, decreasing the likelihood that this person will participate in regular, vigorous exercise. Time constraints may factor in as well, causing the stressed individual to make less healthful food choices. Quick-serve or fast-food restaurants typically do not offer many healthful, low-fat, fresh food or meal options. Additionally, stress hormones, such as cortisol, may stimulate the appetite, exacerbating the issue. Although much of the research shows that those already overweight, or with an elevated BMI, are at the greatest risk, this might be due to the fact that they have not had success in the past controlling their body weight. It takes a good foundation of healthy habits and stress management techniques, practiced over some years, to properly cope with the effects of chronic stress.
References
- American Journal of Epidemiology; Psychosocial stress and change in weight among US adults; JP Block, Y He, AM Zaslavsky, L Ding and JZ Ayanian; May 2009
- International Journal of Obesity; Work stress, weight gain and weight loss: evidence for bidirectional effects of job strain on body mass index in the Whitehall II study; M Kivimäki, J Head, JE Ferrie, et al.; Jun 2006
- Obesity; Stress-related development of obesity and cortisol in women; V Vicennati, F Pasqui, C Cavazza, U Pagotto and R Pasquali; Sep 2009
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