Success in Weight Loss May Be Affected By Sympathetic Nervous System
The sympathetic nervous system is best known for the role in plays in the “fight or flight” response, or the ability of the body to react in the face of danger. However, researchers have also discovered that nervous impulses from this part of the autonomic nervous system may also predict weight-loss outcomes in the overweight or obese. Tapping into this relationship may prove to be an opportunity for developing new weight loss strategies.
When faced with a dangerous situation, the sympathetic nervous system begins sending signals that cause the pupils to dilate, sweating and heart rate to increase, and blood pressure to rise. The same system also controls the physiological functions of resting metabolic heart rate and the dissipation of calories, two very important factors in weight maintenance.
Dr. Nora Straznicky PhD of the Baker IDI Heart and Diabetes Institute in Australia and colleagues examined 42 overweight or obese volunteers who participated in a 12-week dietary-lifestyle intervention trial. Daily caloric intake was cut by 30% and the participants followed the DASH diet. The researchers measured muscle sympathetic nerve activity, or MSNA, with microneurography – a process involving the insertion of metal microelectrodes into bundles of nerve fibers. MSNA is a measure of nervous outflow to the skeletal muscle and represents a direct measurement of sympathetic activity.
Those with higher levels of resting nerve activity were more successful in their weight loss efforts.
This actually isn’t the first study to note the link between the sympathetic nervous system and weight management. In 1993, researchers with the University of Iowa studied MSNA in Pima Indians, a group of people who have a high rate of obesity and Type 2 diabetes among them – up to 10 times the rate of Caucasians, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The team noted that those with reduced activity in the sympathetic nervous system also had lower resting metabolic rates and therefore burned fewer calories, putting them at risk for weight gain.
In addition to weight gain, the sympathetic nervous system also controls body systems that are involved with glucose metabolism. Those with autonomic nervous systems that do not work properly are at risk for developing Type 2 diabetes. Dr. Straznicky did find that carbohydrate intake affected the study volunteers differently, based upon who had adequate MSNA.
While you may not be able to control your nervous system activity, maintaining a regimen of a healthful, low-calorie diet and daily exercise can benefit your health in many ways, including reducing blood glucose levels, reducing blood pressure, and decreasing your risk for cardiovascular disease.
The study entitled “Baseline sympathetic nervous system activity predicts dietary weight loss in obese metabolic syndrome subjects,” will appear in the February 2012 issue of The Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM).
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