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Is The Rat Race Making Us Fat?

By Kellie Heywood

Stressed rodents may have uncovered an important clue about how coping with the rat race of modern life has contributed to people gaining weight.


              Is The Rat Race Making Us Fat?

There has been a lot of discussion about why rates of overweight and obesity have risen so steeply around the world in the last thirty years.

Some of the answers – increased consumption of high fat and high sugar foods and reduced physical activity – are well accepted. But scientists are investigating multiple approaches to trying to solve the great paradox of modern life: why when we’ve never had so much sophisticated health care available are we looking at dealing with epidemics of lifestyle-related diseases such as diabetes and heart disease.

Social stress may be one of the factors. While extreme stress associated with major traumatic events is frequently associated with loss of appetite and weight, low-grade, every-day stress that comes from having to negotiate the social demands of work, family and relationships appears to have the opposite effect. Over time it may trigger overeating and weight gain.

A group of scientists at the University of Cincinnati College of Medicine have studied rats living in close proximity in an attempt to understand why.

Closeness means extra calories?

The researchers put rats who had previously been housed separately into colonies of six – inducing a rodent version of social stress. The rats quickly established hierarchies, sorting out which rats were dominant and which were subordinate.  The scientists monitored their eating patterns during the two weeks the rats lived together and in a recovery period after they were put back into individual housing.

What they found was that when living together the rats eating patterns changed quite markedly. Initially all the rats ate less. Once the dominant rats established themselves at the top of the pack, they went back to their normal eating patterns. The subordinate rats; however, made do with fewer meals.

Once the stress was off, during the recovery period, all the rats began to overeat. But the dominant rats ate smaller, more frequent meals while the subordinate rats ate larger and less frequent meals. And this had an impact on their weight. While the dominant rats gained weight all over, the subordinate ones gained significantly more weight around their abdomens – and increased abdominal weight has been linked with metabolic changes that are known to contribute to diabetes and cardiovascular disease.

A weight loss lesson from the lab

Of course, humans aren’t rats and our social interactions are rather more complicated. But what the study does suggest is that chronic social stress may interfere with the hormones and signals that control appetite and how much we eat – even when the stress is off.

Tackle stress proactively. Be aware of your stress levels and take measures to deal with stress in healthy ways other than overeating.

If it has been a tough day/week/year and you’re feeling the need for some comfort food, try opting for smaller and more frequent meals rather than large meals that can make you feel uncomfortable at the end. It’s also worth figuring out ahead of time some healthier versions of your favourite stress-busting treats so that you can indulge with fewer consequences to your waistline.

Reference:

Melhorn SJ, Krause EG, Scott KA, Mooney MR, Johnson JD, Woods SC, Sakai RR (2010) Meal patterns and hypothalamic NPY expression during chronic social stress and recovery. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 299(3): R813-822.