Faculty of 1000

Post-publication peer review

More food for thought

Posted by stevepog on 24 February, 2010

By Steve Pogonowski and Bea Downing

Work dramas, late bills, latent childhood trauma: adult life is full of potential for the average person to get stressed and deal with it by ‘comfort eating’.

As discussed in a previous post by Callum, labeled ‘Food for thought’ (hence my segued sequel/blatant rip-off title here), there are ongoing studies starting to appear in the earlier pages of top-ranked journals that look at the psychological, rather than purely physical, causes and effects of weight gain and obesity.

But the fact remains that there is still much to learn about the biological processes resulting from the mental stresses of daily life.

In a recent F1000 Biology Report, Faculty Member Achim Peters from the University of Luebeck and Dirk Langemann of Carolo-Wilhelmina-University looked at recent advances detailing how stress affects neurometabolism and eating behavior.

Stress increases the brain’s demand for glucose and, in some people, causes comfort eating and weight gain due to a weak sympathoadrenal response.

Under stress, the brain’s metabolic rate – and glucose demand – shoots up by 12%. Two mechanisms then come in to increase glucose availability to the brain: brain-pull and storage-push. Brain-pull mechanisms increase the percentage and amount of energy that the brain can withdraw from the blood across the blood-brain barrier, while storage-push mechanisms increase blood-glucose levels to flood the system with energy.

During periods of chronic stress, the stronger storage-push response results in the blood being loaded with energy. When the brain’s demand for glucose falls, the storage-push is still releasing glucose into the blood. The remaining glucose is mopped up by insulin and stored as fat.

Peters and Langemann said:

“Evidence accumulates that the stressed mind can choose a metabolic coping strategy by switching its supply mode from brain pull to ‘comfort eating’.”

Chronic stresses in adult life, such as job-related demands and difficulty paying bills, may weaken the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. In adults with depression and anxiety, weight gain and the risk of obesity were increased in a dose-response fashion with the number of episodes of these common mental disorders.

Problems can also strike earlier in life: early-life stress and juvenile trauma result in long-lasting changes in the activity of the autonomic nervous system and body weight. Prenatal psychosocial stress exposure is associated with hyperinsulinemia in later life, a strong predictor of weight gain and a typical marker of brain-pull inefficiency.

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