0 Overeating impairs brain insulin function can lead to diabetes and obesity

New research from Mount Sinai School of Medicine sheds light on how overeating can cause a malfunction in brain insulin signaling, and lead to obesity and diabetes. Christoph Buettner, MD, PhD, Associate Professor of Medicine (Endocrinology, Diabetes and Bone Disease) and his research team found that overeating impairs the ability of brain insulin to suppress the breakdown of fat in adipose tissue.

In previous research Dr. Buettners team established that brain insulin is what suppresses lipolysis, a process during which triglycerides in fat tissue are broken down and fatty acids are released. When lipolysis is unrestrained, fatty acid levels are elevated, which can initiate and worsen obesity and type 2 diabetes. The current study is published online in The Journal of Biological Chemistry. The first study was published in the February 2, 2011 issue of Cell Metabolism.

"We are interested in understanding why people who eat too much eventually develop diabetes. Our recent studies suggest that once you overeat, your brain develops insulin resistance. Since brain insulin controls lipolysis in adipose tissue by reducing sympathetic nervous system outflow to adipose tissue, brain insulin resistance causes increased spillage of fatty acids from adipose tissue into the blood stream," said Dr. Buettner.

Increased fatty acids induce inflammation and that, in turn, can further worsen insulin resistance, which is the core defect in type 2 diabetes. Fatty acids also increase glucose production in the liver which raises blood glucose levels, Dr. Buettner explained. "Its a vicious cycle and while we knew that this can begin with overeating, this study shows that it is really the brain that is harmed first which then starts the downward spiral."

In this study, researchers fed rats a high-fat diet comprised of 10 percent lard for three consecutive days. This increased their daily caloric intake by up to 50 percent compared to the control rats that were fed a regular low fat diet. The researchers then infused a tiny amount of insulin into the brains of both groups of rats that they had shown in earlier studies to suppress release of glucose from the liver and fatty acids from fat tissue. They found that overeating impaired the ability of brain insulin to suppress glucose release from the liver and lipolysis in fat tissue. Similarly, short-term overeating in humans is known to produce comparable insulin resistance which could be explained by brain insulin resistance.

"When you overeat, your brain becomes unresponsive to these important clues such as insulin, which puts you on the road to diabetes. We believe that what happens in rats also happens in humans" said Dr. Buettner.

Dr. Buettners team plans to investigate methods of improving brain insulin function that could restrain lipolysis and improve insulin resistance.

0 Overeating Can Double the Risk of Memory Loss Leading to Cognitive Decline

Compelling research will be presentedat the American Academy of Neurologys 64th Annual Meeting to explain how overeating may double the risk of memory loss, or mild cognitive impairment (MCI), among people aged 70 and older. Cognitive decline threatens the very nature of who we are and how we interact with others and the number of individuals experiencing the normal loss of thought and memory has been increasing over the past half century.

Loss of cognition and early stage dementia are both precursors to the devastating condition diagnosed as Alzheimer’s disease, said to affect nearly half of those aged 80 and above. Calorie restriction initiated early in life may be one of the most effective tools available to combat cognitive decline and memory loss leading to dementia.

High Caloric Intake is Shown to Double the Risk of Cognitive Decline in Seniors

The studywas conducted using 1,233 individuals aged 70 to 89 who were free of dementia and living in Minnesota. Each participant filled out a questionnaire detailing the number of calories they ate or drank, and were then broken into three groups based on total caloric consumption. A third of the participants consumed between 600 and 1,526 calories per day, the middle third ranged between 1,526 and 2,143 and the top third consumed between 2,143 and 6,000 calories per day.

The lead study author, Dr. Yonas Geda noted of the initial findings, “We observed a dose-response pattern which simply means; the higher the amount of calories consumed each day, the higher the risk of MCI.” The team discovered that those consuming the highest number of calories (2,143 calories per day and up) more than doubled their risk for developing MCI. The researchers adjusted for history of stroke, diabetes, amount of education, and other factors that can affect risk of memory loss to reach their conclusion.

Dietary Restriction Lowers Oxidative Damage to Delicate Brain Structures

It is important to note that participants in the lower two-thirds experienced no increased risk of MCI, leading to the conclusion that the body is able to metabolize calories to an individual set point before cognition is impaired. Dr. Geda commented “excessive caloric intake may lead to oxidative damage leading to structural changes in the brain… cutting calories and eating foods that make up a healthy diet may be a simpler way to prevent memory loss as we age”.

It comes as no surprise to those following healthy lifestyle principles that caloric intake is yet another lifestyle factor found to affect the brain and impact normal thinking and memory processes as we age. Researchers have known for decades that calorie restriction is the only demonstrated mechanism to extend healthy lifespan, as it is shown to stress the body’s natural survival mechanism toward longevity. Cutting 20% of your daily calories in the form of hydrogenated and trans fats, ined carbohydrates and excess animal protein will not only help you maintain a normal body weight, but may help prevent cognitive decline in your senior years.