Stress and diabesity -
cause and effect
Certain levels of stress may be considered ‘healthy’ (for example in performance enhancement) but generally speaking we refer to stress as being negative and unhealthy. We all know that an elevated unhealthy type of stress is a risk factor for cancer, hypertension and CVD. In this article I would like to discuss how stress influences eating behaviours that may lead to diabesity. A substantial amount of scientific research has been committed to unravelling this complex issue. Although it has been claimed that some individuals may gain more weight under stressful circumstances, whilst others may lose weight and still others may have little change in weight, yet for the vast majority, stress is likely to lead to higher food consumption, fat accumulation in the midsection, weight gain and diabesity.
Stress could be defined as the body’s nonspecific response to any stimulus that overcomes, or threatens to overcome, the body’s ability to maintain its systems in constant stability (homeostasis). The stress response may be caused by social stressors (e.g., life events, personal conflicts); physiological stressors (e.g., pain, tough workouts, intense heat or cold); psychological or emotional stressors (e.g., sadness, fear, anxiety); and/or chemical stressors (e.g., blood acid-base imbalance, low oxygen supply).
Physiologically, the human body responds differently to acute and chronic type of stress. If the stressor represents an “ongoing” hassle, fear or overwhelming issue in an individual’s life (such as bad relationships, economic problems, on persistent health issue etc.) the effect is referred to as chronic stress. In contrast, if the stressor is more transitory and immediate, the effect is referred to as acute stress. The body perceives an acute stressor (e.g., being stuck in traffic) as a challenge that a human being is capable of handling. On the other hand, chronic stress may seem unmanageable.
During periods of acute stress, the medulla part of the brain signals the release of several “stress hormones,” including adrenaline and noradrenaline from the adrenal glands. These hormones trigger physiological “fight-or-flight” mechanisms, which include increased heart rate, respiration rate, fat and carbohydrate metabolism, and blood pressure. Simultaneously, the body slows down other physiological processes, such as blood flow to the digestive system, appetite and food intake. The body is preparing itself with immediate energy, reflexes and muscular strength which it may need to act in response to the stressor. This is an automatic physiological response to a real or perceived risk that endangers an individual’s immediate existence. When the threat that triggered this response has been eliminated, the body and mind return to a state of homeostasis.
When it comes to chronic type of stress, the hypothalamus (the central control centre for stress in our brain) directs the pituitary gland (which is just below the hypothalamus) to send a signalling message hormone (adrenocorticotropic hormone, or ACTH) to the adrenal cortex (the outer layer of the adrenal glands above the kidneys). ACTH triggers the release of cortisol (a stress hormone). This reaction is referred to as the hypothalamic-pituitary-adrenocortical (HPA) axis, and it is most active in humans during the early-morning hours.
If the chronic stress (whether real or perceived) is of sufficient degree and duration, the HPA does not wind down (as it should), resulting in prolonged rising of cortisol levels. Therefore, chronic stress leads to daily increases of cortisol secretion.
The hormone Cortisol is known to induce appetite during the intermittent recovery periods that occur when an individual is experiencing chronic stress. Cortisol (with the help of slightly elevated insulin levels) has also been known to activate lipoprotein lipase, the enzyme that facilitates the storage of fat. When insulin levels are slightly higher, elevated cortisol levels inhibit the breakdown of triglycerides, thus promoting fat storage. There is evidence that chronic stress consistently contributes to greater central fat accumulation in females than in males.
Additionally, chronic stress is associated with emotional changes that can include increases in anxiety, apathy and depression. This in turn is likely to lead to much higher food consumption, referred to as stress-induced or emotional eating.
Stress-induced or emotional eating may be defined as making oneself feel better by eating or drinking in response to a stressful situation.
The fact that during periods of chronic stress, people often have limited time or patience to prepare healthy food choices seems to contribute to their tendency to make bad dietary choices. Research suggests that overweight individuals tend to eat more when exposed to chronic stress, whereas normal-weight or underweight individuals do not. It appears that people who are chronically stressed—regardless of whether they eat more or less—tend to choose more pleasurable or palatable foods containing higher levels of processed fat and/or sugar.
Although eating highly palatable foods seem to temporarily decrease stress levels, it stimulates more eating of pleasurable foods. Thus, dealing with life’s stressors using food can become an incessant cycle that continues to contribute to diabesity.
Amongst many of the stress reduction and management methods known, meditation and physical activity are dominant and combined are likely to produce better results in protecting 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.
Although the measurements of stress are not considered to be uniform, there is a universal consensus that physical activity and practicing meditation decrease stress levels and increase feelings of well-being.
Physical activity provides a distraction from stressful situations, as well as an outlet for frustrations. In many ways it acts as a buffer to the overflow of hormones that accumulate from daily stress. When it comes to physical activity there does not appear to be a differential effect based on the type of activity (e.g., running, swimming, cycling, elliptical training, etc.). As to exercise intensity, there are indications that moderate to vigorous physical activity (done regularly) tend to reduce stress better than low-intensity activity.
Similarly, when it comes to meditation there does not appear to be a differential effect which is based on the type of meditation (e.g., HeartMath, Mindfulness or other traditional methods of meditation).
When in a meditative state, deep centring occurs with a focus on the core of our being; this in turn allows for a quieting of the mind and emotions, which helps relax tensions. During meditation, the brain enters an area of functioning similar to sleep, but with added benefits that we cannot achieve in any other state; these benefits include the release of certain hormones that promote health.
However, there are added benefits in engaging in activities which combine both meditation and physical activities (mind-body). For example, Yoga, Tai-Chi, Stretching etc.
Stress sends biochemical “shock waves” throughout the body that might be useful in the short term (I have mentioned performance enhancement). However, chronic stress unleashes a torrent of hormones that are likely to become toxic as the stress persists. Healthcare professionals should be encouraged to educate their clients on the importance of exercise and mind-body practices in reducing the metabolic and physiological effects of stress and potentially lowering the risk of CVD, hypertension and diabesity.