OVEREATING CAUSES BRAIN INSULIN RESISTANCE, INCREASING DIABETES RISK

New research suggests that chronic overeating can lead to insulin resistance within brain cells, and when the brain becomes insulin resistant it fails to properly regulate the breakdown of fat stored in the body as well as the production of glucose by the liver.

While stored fats are important energy sources during fasting, their release into the bloodstream when the body is in a fed state, leads to multiple metabolic problems including elevated blood sugar and blood cholesterol, and increased levels of inflammation throughout the body. Previously it was believed that insulin's ability to suppress fat breakdown in healthy persons was entirely mediated through the fat tissue cells but recent findings suggest that brain cells’ response to insulin is a key regulator of fat breakdown. 

In this most recent study, Dr. Christophe Buettner and his research team at Mt. Sinai School of Medicine demonstrated, at least in rats, that overeating drives brain insulin resistance. For 10 days researchers fed one group of rats their usual weight- maintenance diet while they fed another group a diet with 150% of their caloric needs. The researchers then infused a tiny amount of insulin into the brains of both groups of rats. Unlike in the control diet group, in the overfed group, the addition of insulin to the brain failed to suppress the release of glucose from the liver and fatty acids from fat tissue. While this study was not conducted in humans, it is probable that a similar process of brain insulin resistance occurs in humans.  Certainly human studies have demonstrated that temporary overeating produces similar patterns of metabolic dysfunction in the liver and fat tissue. 

What to do: These findings remind us that not only excess weight but that overfeeding itself also drives insulin resistance and the metabolic problems that lead to diabetes and heart disease. Certainly, maintaining a healthy weight by following a healthy diet moderate in calories and getting regular activity minimizes the risk of diabetes.  But, even among persons with excess weight, avoiding overeating (even when weight loss is not achieved) can help to moderate insulin resistance and the processes that drive the development of diabetes.

Adapted from article available at: http://www.sciencedaily.com/releases/2012/10/121017153911.htm & http://www.sciencedaily.com/releases/2011/02/110216123547.htm

Sources:

T. Scherer, C. Lindtner, E. Zielinski, J. O'Hare, N. Filatova, C. Buettner. Short Term Voluntary Overfeeding Disrupts Brain Insulin Control of Adipose Tissue Lipolysis. Journal of Biological Chemistry, 2012; 287 (39): 33061 DOI: 10.1074/jbc.M111.307348.

Thomas Scherer, James O'Hare, Kelly Diggs-Andrews, Martina Schweiger, Bob Cheng, Claudia Lindtner, Elizabeth Zielinski, Prashant Vempati, Kai Su, Shveta Dighe. Brain Insulin Controls Adipose Tissue Lipolysis and Lipogenesis. Cell Metabolism, 2011; 13 (2): 183 DOI: 10.1016/j.cmet.2011.01.008