Saturday, May 13, 2017

Visual cues and subsequent energy intake

The Study
Larger portion sizes have been shown to increase energy intake in the research literature. A recently published study attempts to explain why. Thirty-six children between the ages of 7 and 10 were shown a variety of pictures while undergoing a brain MRI scan. Some of the pictures were of large portion sizes, some were of small portion sizes. Some of the pictures where of high energy density junk foods (like chicken nuggets, French fries and cookies) and some were of low energy density healthy foods (like grilled chicken, green beans and blueberries).

The results were fascinating. When the children were shown pictures of foods with large portion sizes, there was a decrease in activity in the region of the brain called the inferior frontal gyrus. This region is important for inhibition. When the children were shown pictures of the high energy density junk food, there was an increased activation in the insula, caudate and cingulate. These parts of the brain deal with reward and taste processing. American Journal of Clinical Nutrition 2017; 105:295-305.

Take Home Message
This is a really interesting study. Just seeing pictures of foods that were large in portions or energy dense changed the brain in a way that increased the desire to overeat. When I first started studying nutrition and weight loss in the early 2000’s, the prevailing wisdom was that losing weight was simply about eating less and exercising more. 

It is now clear that there is a lot more going on. There are a multitude of factors that impact our food choices and cravings. The results of this study add simple visual cues to the growing and complex list of body systems that impact what we eat and how much we eat. We are learning a lot but still have a ways to go. If you find yourself in the presence of tempting foods that you do not want to eat, look away! J

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