Carbohydrates are found in sugar, bread, cereals, fruits and vegetables.  All carbohydrates, with the exception of fiber which is indigestible, are broken down into sugar and the resulting increase of glucose in the bloodstream causes insulin to be released.  Insulin shuttles the glucose to muscle and liver cells resulting in a lowering of blood sugar.

Refined carbohydrates, found in refined flours and sugars, are more easily digested by the body leading to higher levels of blood glucose and a greater insulin response than less processed carbohydrates such as whole grains, beans, fruits and most vegetables.  This heightened insulin response to refined carbohydrates leads to a more rapid decline in blood glucose from peak levels and causes a more rapid return of hunger.

High glycemic index diets, from refined carbohydrates, increases the risk of coronary heart disease by 1.98 times compared with low GI diets.¹  Furthermore carbohydrates classified by glycemic index were found to be a stronger predictor of coronary heart disease than the traditional classification of “simple” and “complex”.  This again suggests that the glycemic index is a more accurate measure of a carbohydrate’s effect on our blood chemistry and resulting health.

1.                  A prospective study of dietary glycemic load, carbohydrate intake and risk of coronary heart disease in women. Am J Clin Nutr 2000;71:1455-61

Results of the Nurses’ Health Study, a longitudinal study of diet and lifestyle factors among 65,000 Nurses followed since 1986, suggest that diets with a high insulin demand (high glycemic index) lead to an increased risk of diabetes.¹

In this study, Dr. Walter Willet at the Harvard school of Public Health, found that high glycemic diets (which included cola beverages, white bread, white rice, French fried potatoes, and cook potatoes) increased the risk of developing diabetes by 1.47 times compared with low glycemic diets.  Furthermore when dietary fiber was factored in, diets with a high glycemic index and low cereal fiber increased the risk by 2.5 times.

Another study of 43 thousand Finish men and women found a 35% risk reduction of developing diabetes in participants with high whole grain intake compared to participants with low whole grain intake.² Although not measured directly, this suggests that a low GI diet represented by a high whole grain intake reduces the risk of diabetes mellitus.

1.                  Dietary Fiber, Glycemic Load, and Risk of Non-insulin-dependent Diabetes Mellitus in Women.  1997 JAMA; 277:472-477

2.        Whole-grain and fiber intake and the incidence of type 2 diabetes.  2003 Am J Clin Nutr;77:622-9

Physical fitness and your health

In a study by Steven Blair of the Cooper Institute increasing levels of physical fitness as measured by a treadmill test lowered the risk of mortality.¹ Specifically least fit men had mortality rates 3.44 times higher than most fit men. For women the mortality rate was 4.65 times higher. Maximal fitness benefits with lower risks of mortality were attainable by individuals who engage regularly in moderate exercise (equivalent to a brisk walk of 30-60 minutes each day).

In 1995 the Centers for Disease Control and the American College of Sports Medicine advised American adults to accumulate 30 minutes or more of moderate-intensity physical activity on most, preferably all, days of the week.² Examples of moderate activities cited included brisk walking (3-4 mph), cycling less than 10 mph, swimming, moderate effort, conditioning exercise, racket sports, home care and general cleaning and mowing the lawn. Remember that these recommendations are to improve fitness and are not related to weight loss maintenance where greater levels of activity are required.

Fitness benefits for those overweight

It’s no surprise that obesity can be dangerous to your health. Studies from the Cooper Clinic demonstrate that overweight individuals have a 3 times higher cardiovascular death rate and double the overall mortality rate when compared to normal weight men.³

However when cardiovascular fitness was considered, fit obese individuals had lower mortality rates equivalent to fit lean men!⁴ Or put another way, unfit lean men had twice the risk of mortality of fit obese men. Clearly fitness offers equivalent protective health benefits for overweight individuals as compared with lean individuals.

1. Physical Fitness and All-Cause Mortality. JAMA 1989;262:2395-2401

2. Physical Activity and Public Health. A Recommendation From the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273:402-407

3. Relationship Between Low Cardiorespiratory Fitness and Mortality in Normal-Weight, Overweight, and Obese Men JAMA;282:1547-1553

4. Cardiorespiratory fitness, body composition, and all-cause and cardiovascular disease mortality in men. AM J Clin Nutr 1999;69:373-80

Americans are becoming more overweight

Americans have become more overweight and obese.¹ The prevalence of overweight (defined as a BMI 25 or higher) increased from 56% to 65% largely due to the rising prevalence of obesity (defined as a BMI of 30 or higher) which increased from 23% to 31%.  These results are alarming and the health implications will be profound. 

Obesity is as detrimental to your health as smoking

We have known that overweight and obesity are detrimental to our health but life expectancy results from the Framingham Heart Study are astonishing.²  Non-smoking obese adults (BMI >_ 30) at age 40 lived 6 to 7 years less than their normal weight counterparts.  These decreases in life expectancy are similar to that seen with smoking.  For non-smoking overweight individuals (BMI 25-29.9) lived about 3 years less than their normal weight counterparts.