The Halo Effect of Exercise : The Antidote to Sugar Addiction?

      Why is it that we eat right when we are in an exercise routine and then if that routine is interrupted (usually due to an injury or work schedule), then our “diet” goes out the window soon after?  This has been described as the “halo effect” of exercise in studies, and recently there was a scientific article that perhaps described why.

    In this article in the journal Obesity, in a study conducted at my alma mater (University of Southern California),  22 participants underwent functional MRI scans while being exposed to food and non food images.  In a functional MRI, brain activity can be measured in the pleasure and addiction centers of the brain (so called “regions of interest”).  They found that greater number of minutes of moderate to vigorous physical activity was associated with decreased food cue reactivity after glucose exposure across brain regions of interest and that greater sedentary behavior was associated with increased food cue reactivity after glucose exposure.   In other words, you may be more prone to sugar cravings when you are sedentary than baseline and even more so compared to when you are active.   Couple that with the food environment at work which frequently has sugary snacks in the break room or candy dishes, and you have a "double whammy."  Remember also that sedentary behavior adversely affects your metabolic milieu.
     But that's not all.  In sub group analysis, these results were only true in participants with obesity, and not in participants with lean body fat percentage.  This may be due to the active endocrine effects of excess adipose tissue,or it could be part of the underlying disease of obesity, and would not be resolved by reduction in excess fat.  In either case, yet another example of how excess weight is not just “calories in, calories out," and why the disease needs treatment, not a diet, and long term treatment, even for weight maintenance. 

   This activity on functional MRI may be the same area targeted by the medication Contrave. If you experience intrusive thoughts and craving for certain trigger food, or experience difficult to control urges to consume food when not hungry, this can be due to this brain chemistry seen on functional MRI and may be the target mechanism of action of the medication Contrave, an FDA approved medication for the treatment of the disease of obesity.  Learn more at a consultation with us.  Pharmacotherapy should be considered as part of a comprehensive treatment plan. 

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Valerie Sutherland MD

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