Joslin Diabetes Center Research | Obesity and Diabetes
Director, Obesity Clinical Program, Joslin Diabetes Center; Instructor in Medicine, Harvard Medical School
The incidence of obesity in the U.S. is rising dramatically: two-thirds of adult Americans, and more and more children, are overweight or obese. From 1994 to 2000, the average waist size of Americans increased by more than one whole inch. This bulging of American waistlines parallels an alarming rise in diabetes. Excessive weight is a risk factor for diabetes and also increases ones chances of having life-threatening heart attacks and strokes.
Weight gain is the enemy, but the good news is that we know how to fight it. Our target is the fat cell. Take in more food than the body needs, and the excess is stored in fat cells, which keep swelling in size and increasing in number. But start taking in less food, and burn more calories in the form of physical activity, and those fat cells will literally shrink. Research on this subject is loud and clear: diet and physical activity are effective, and its never too late to start.
A Weighty Impact on Insulin
The job of insulin is to get glucose from the foods we eat into the cells of the body, where energy is created to power critical functions in the muscles and other body organs. When people gain weight, particularly around their waists, their insulin sensitivity decreases. This decrease in insulin sensitivity is the beginning of a problem that, in genetically susceptible people, leads to insulin resistancea condition in which the cells do not respond to insulinand consequently type 2 diabetes. If the cells dont receive enough glucose because of insulin resistance, they clamor for more. The pancreas can compensate for awhile by making more insulin. To add to the vicious cycle, insulin may cause further weight gain, which in turn triggers the need for more glucose. Over time, the pancreas becomes exhausted and less effective.
We now have a huge sector of the American population with pre-diabetesas many as 40% of all U.S. adults over age 40, according U.S. Department of Health and Human Services estimates. People with prediabetes have glucose levels that are above normal but are not yet high enough for a diagnosis of diabetes. People with so-called metabolic syndrome are also considered to pre-diabetes. Metabolic syndrome condition in which one has several problems that all come together: obesity, insulin resistance, high blood pressure and abnormal cholesterol and triglyceride levels. This is a significant problem because not only are people with prediabetes at risk for diabetes, they are the fast track to Americas number killer: coronary artery disease.
Fat Is Not Filler
Research has taught us much about body fat. We know, for instance, that the fat that resides below the waist area is the most dangerous to our health. We also know that fat isnt just an inert couch-potato cell. A fat cell is a busy machine, churning out hormones and chemicals. One of these chemicals plays a major role in controlling appetite, and another has a significant role in determining the bodys sensitivity to insulin. But others trigger destructive inflammation that may damage the lining of arteries and contribute to its thickening and hardening (atherosclerosis), leading to coronary heart disease and cerebral stroke.
Wed like to report that sucking out fat is the cure. Liposuction does precisely that, sucking out the subcutaneous fat just below the surface of the skin. Yet researchers earlier this year reported that in a study of 15 people, in which an average of 10 kilograms (about 22 pounds) of subcutaneous fat was removed, there was no noticeable change in their glucose, blood pressure and cholesterol levels despite the weight loss. In other words, it didnt reverse the disease process because it is the visceral fat the deeper fat that curtains the intestines and abdominal wallthat is directly involved in insulin resistance and inflammation. A JoslinBeth Israel Deaconess Medical Center clinical research study will attempt to determine whether surgical removal of visceral fat, a much more difficult operation, will be more successful.
In the meantime, the only way to truly prevent, or even reverse, type 2 diabetes in the early stages is through diet and physical activity. Studies at Joslin and elsewhere demonstrate that a 7% weight loss (16 pounds if one weighs 220 pounds, for example) combined with moderately intensive physical activity (90-150 minutes a week) will improve insulin sensitivity, reduce inflammation in blood vessels, lower glucose levels and improve blood vessel function. (It is important to always check with your health care provider before increasing your physical activity or beginning a new physical activity program.)
We know the enemy. Its too much of the wrong types of fats found in the large portions we eat, resulting in too much fat in the wrong places in our bodies. But if we dont do something, the enemies multiply. Instead of just dealing with fat, we could be facing diabetes, coronary artery disease, stroke or cancer.
This article first appeared in the Nov. 1, 2004 issue of Time magazine.Courtesy of Joslin Diabetes Center
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