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Lifestyle factors key in developing, preventing & reversing type 2 diabetes & heart disease

Apr 22, 2002

Lifestyle factors have now been established as the key in developing 1 as well as preventing and reversing type 2 diabetes 2, 3 and heart disease.4

Hu and his colleagues at Harvard School of Public Health followed more than 42,000 male health professionals for 12 years and found that those who consumed a typical “western” diet—including lots of red and processed meat, high-fat dairy products, French fries, and refined grains, sweets, desserts, high-sugar drinks, and other rapidly absorbed, high-glycemic index (high GI) carbohydrates—are much more likely to develop diabetes than those whose diets center on vegetables, fish, and poultry, more fiber, higher intakes of protein, as well as less refined and more slowly absorbed, low-GI carbohydrates. 1 The 20 percent of the men who were closest to the typical western diet were 60 percent more likely to develop diabetes than the 20 percent who were best at following a healthier diet. The combination of a western diet with a low level of physical activity or obesity was associated with a particularly high risk of type 2 diabetes. Of interest, saturated fat and total fat were not appreciably associated with the risk for type 2 diabetes. 1


The Diabetes Prevention Program shows that weight loss with diet and exercise can reduce by 58 percent the incidence of type 2 diabetes in high-risk men and women. This is twice as effective as prophylactic treatment with metformin. 5 While a typical western diet increases the risk of developing type 2 diabetes and CHD, a healthy diet and lifestyle can prevent and reverse the risks. But what constitutes a “healthy” diet? Evidence supports lowering glycemic load (the amount of rapidly digested and absorbed carbohydrates), eliminating trans fats, and emphasizing monounsaturated and omega 3 fatty acids. These dietary measures have been shown to improve glycemic control, 6, 7 insulin sensitivity, 8 9 and lipid profiles, 6, 7 10 thereby reducing the risk of diabetes 8, 11-14 and coronary heart disease (CHD). 6, 7, 9, 15, 16

Research suggests an association with lifestyle, worry, cortisol levels, and abdominal girth. Those who were found to have the highest levels of chronic stress had the highest levels of cortisol and visceral abdominal fat. The researchers suggest that chronic stress leads to elevated cortisol levels, which may lead to the insulin resistance syndrome. There is also evidence that a number of medications, including prednisone, may cause an excess of cortisol and insulin resistance. Taken orally, cortisol raises blood pressure, and it has been shown to impair brachial artery blood flow in response to an acetylcholine challenge, i.e., an indicator of endothelial dysfunction. 17-24 Even brief episodes of mental stress, such as those encountered in daily life, may cause transient endothelial dysfunction even in young, healthy individuals. 25, 26 In turn, subsequent cytokine release may increase anxiety and have negative effects on emotional and memory functions. 27

In a recent study, patients with type 2 diabetes followed a stress management protocol including progressive muscle relaxation, mental imagery, breathing techniques and instructions on how to modify one’s physiologic, cognitive and behavioral responses to stress. They showed, on average, a 0.5 percent reduction in HbA1c, while by the end of one year, 32 percent of the patients in that group showed an even greater improvement by lowering their glucose level by 1 percent or more. According to the authors, that amount of glucose level reduction is what the Food and Drug Administration (FDA) considers sufficient when reviewing drugs seeking approval for diabetes control. The control group in six months began to show deterioration in their glucose levels, while the stress management group continued to improve. 28

Level of fitness is a powerful predictor for diabetes 29 and all-cause mortality. In a report from the Cooper Institute for Aerobics Research in Dallas, Texas unfit men were twice as likely to die from CHD and inactive men were 70 percent more likely to die during the study period than active men. 30, 31 In a study of 25,000 men followed for an average of eight years, the fatter the men the greater the mortality risk. However, when categorized according to level of cardiorespiratory fitness (treadmill performance), weight did not matter as much as fitness levels. Even those who were physically fit, but obese, had a lower risk of dying than unfit men of normal weight. 32 Being unfit is a greater risk factor than obesity. Compared to fit men, low fitness men were twice more likely to die from any cause than were men with better cardiorespiratory fitness. Besides being 7.4 times more likely to die from diabetes, these unfit men were also twice as likely to die from heart disease. Fit men were found to have greater longevity than unfit men regardless of their body composition or risk factor status, e.g., cholesterol levels. Patients with diabetes and a high fitness level were found to have at least a 70 percent lower risk of dying. 31

A British study followed over 5,000 apparently healthy men aged 40 to 59 over an average of 17 years. In addition to fewer MIs, strokes, and cases of diabetes, a moderate level of physical activity was associated with a 50 percent reduction in the risk of having abnormal liver enzymes (GGT), 40 percent reduction in risk of having high insulin levels, 30 percent reduction in risk of elevated triglycerides, a 25 percent reduction in risk of having low HDL levels, and reductions in diastolic hypertension. 33 Exercise (aerobic and resistance training) improves endothelial function, 34 35 insulin sensitivity, 36 hyperglycemia, blood pressure, raises HDL, increases lipoprotein lipase that breaks down triglycerides, 37, 38 reduces body fat, and reduces a tendency to coagulation, 38 lowers secretion of tumor necrosis factor alpha (TNF-a) 39, 40 , reduces CRP, and decreases the atherogenic activity of blood mononuclear cells in persons at risk of developing CHD. 41

Sumo wrestlers—an example of fit and fat becomes fat and sick

Japanese sumo wrestlers are a good example of how exercise can only do so much for so long to offset the harmful effects of obesity. Competitive sumos carry most of their abdominal fat subcutaneously with relatively little visceral fat (which is more strongly associated with insulin resistance). 42 They are able to maintain insulin sensitivity until after they retire when they develop large amounts of abdominal visceral fat, insulin resistance, type 2 diabetes, cardiovascular disease and premature death. 42, 43

Eric S. Freedland, MD graduated from University of Rochester School of Medicine in 1982, trained in internal medicine at Mt. Auburn Hospital in Cambridge, MA, and emergency medicine at Harbor-UCLA Medical Center in Torrance, CA, and has held faculty positions at Harvard Medical School (1990-1991) and Boston University School of Medicine (1992-1997). Dr. Freedland has developed a nutrition-centered model of disease with a special emphasis on diabetes. A staunch advocate for prescribing lifestyle changes before drugs, Dr. Freedland has written and lectured extensively on this subject.


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