by Bonnie Bayley
Are you gaining weight despite your best efforts to stay in shape? Your body’s stress hormone cortisol may be the culprit.
When you’re under stress, sticking to a healthy eating and exercise plan can be challenging. You may find yourself reaching for comfort foods, snacking absentmindedly or skipping the gym because of your busy schedule. Next thing you know, a few kilos have crept on. But it turns out, weight gain when you’re under pressure is partly due to cortisol, a hormone which can promote fat storage, slow metabolism and affect your appetite.
The cortisol connection
Known as ‘the stress hormone’, cortisol is secreted by your adrenal glands in response to stress, priming your body to respond by increasing glucose in the bloodstream and curbing bodily functions that are non-essential in a fight-or-flight situation.
Cortisol levels typically return to normal after stress subsides, but if you’re constantly wired and on edge, your body’s stress response may be over-activated, increasing your levels of circulating cortisol.
Stress and weight gain
So, how exactly does cortisol affect your weight? During periods of chronic stress, cortisol levels rise, sending a signal to fat cells to store as much fat as possible - and to hold onto those fat stores, making it trickier to shift the weight.
So, if you’re battling belly fat, cortisol may again be to blame, as research shows it promotes fat accumulation in the abdominal area.1,2
Heightened cortisol can also lead to muscle loss and slow your metabolic rate, neither of which is ideal for staying in shape.
Cortisol and appetite
As well as influencing how your body stores and burns fat, cortisol affects your appetite; this can explain why that packet of biscuits becomes almost irresistible when you’re stressed.
In a University of Leeds UK study, women who were ‘high cortisol reactors’ (that is, their cortisol spiked under stress) scoffed more snacks in response to daily stresses than their more chilled out, ‘low cortisol reactor’ peers. They were also more prone to emotional eating and lack of self-control around food.3
Taming the stress response
Regular exercise and sufficient sleep are vital to managing stress, as is finding a calm-inducing, stress management strategy that works for you. It might be a relaxing yin yoga class or meditation, deep breathing or time in nature.
Ironically, if you’re trying to lose weight, going on a strict diet could be counterproductive. A University of California study found strict dieting boosts cortisol production which, as we know, undermines weight loss.4
Stick to a healthy, balanced diet based on whole foods.
 Talbott S. The cortisol connection. 2nd edition. Hunter House Publishers: CA, 2007.
 Epel ES, McEwen B, Seeman T, et al. Stress and body shape: stress-induced cortisol secretion is consistently greater among women with central fat. Psychosom Med 2000;62(5):623-632.
 Newman E, O'Connor DB, Conner M. Daily hassles and eating behaviour: the role of cortisol reactivity status. Psychoneuroendocrinology 2007;32(2):125-132.
 Tomiyama AJ, Mann T, Vinas D, et al. Low calorie dieting increases cortisol. Psychosom Med 2010;72(4):357-364.