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21 September 2010

Stress – can it make you fat?

The link between stress and weight gain is receiving a great deal of media attention these days and you might be wondering whether all this hype is actually based on fact.

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The link between stress and weight gain has received a great deal of media attention and you might be wondering whether all this hype is actually based on fact.

One of the first points to consider is how different people handle stress. For some, stress is highly motivating and somehow they are able to dig deeper, reach higher and achieve what they didn't dare dream was possible. Others don't feel they can cope and respond by grabbing the closest box of chocolates as pressure rises.

Clearly, the relationship between stress and eating behaviour is complex and varies from individual to individual. Questions that frequently arise regarding stress and food are:

Does stress...

  • actually reduce our willpower?
  • increase our appetite?
  • increase our risk of suffering from serious health problems i.e. cardiovascular disease, diabetes etc?

What happens when we are stressed?
The hypothalamus (part of the brain) sends a signal to the adrenal glands to release cortisol, whether the stress is physical or emotional. Cortisol in turn releases glucose (sugar) and fatty acids into the bloodstream in order to provide energy to the muscles so they can respond to the stress. Too little cortisol release can result in hypoglycaemia (low blood sugar), whereas an excess of released cortisol can cause hyperglycaemia (high blood sugar), which, if persistent and chronic, could lead to diabetes.

Researchers Greenspan and Baxter, 1994, also report that high levels of cortisol can increase appetite and food intake, and later, fat deposits in the trunk and abdominal area, producing the "spare tyre" with which many of us are so familiar. What happens with chronic stress is that the cortisol levels remain elevated for long periods of time.

This can lead to "overworked" adrenal glands resulting in less cortisol release, i.e. a blunted effect. Scientists Rosmond et al, 2000, having researched this area extensively, suggest that overworked adrenals may trigger a vicious cycle of hormonal imbalances, possibly linked to dysfunction of the heart and increased obesity in men. The same effect has frequently been found in women.

Therefore, chronically elevated cortisol appears to be associated with diabetes, high blood pressure, obesity and cardiovascular (heart) disease. However, research also indicates that there may be a link with mental disorders, such as depression.

The table below gives more detail about how the stress hormone cortisol affects the body:

  • regulates carbohydrate, fat and protein metabolism
  • affects muscle tone and microcirculation
  • raises blood pressure
  • increases gastric secretion
  • alters connective tissue response to injury
  • impairs cartilage repair
  • increases inflammation
  • shrinks lymphatic tissue
  • increases allergic and immunological responses
  • stimulates the central nervous system
  • increases appetite and fat deposits, especially in the cervical area, trunk and abdomen
  • increases the risk for developing diabetes

Stress and eating
Not only can stress increase our appetite, it typically makes one crave foods that are calorie-laden and lacking in nutrients. Some "stress-eaters" go for high-energy foods containing sugar and fat (e.g. chocolate), others prefer salty foods (e.g. savoury chips) and then there are those who choose crunchy foods (e.g. potato chips, crackers).

Some people initially lose their appetite when facing a stressful situation, but typically about 40% of these individuals begin to eat excessively about six weeks after the onset of stress, ultimately putting on weight.

- This article was written by Kathleen Mc Quaide (exercise physiologist and educationalist): Health Promotions Manager at the Sports Science Institute of South Africa (SSISA).
For more information about the health, wellness and fitness services offered at SSISA, visit their website www.ssisa.co.za or phone 021 659 5600.

 
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