We all know that extra weight can increase the risk of heart disease and diabetes, but new information shows that body size is not the best predictor of health risk. In other words, skinny does not mean healthy, and chubby does not mean unhealthy.

In two research studies published in the Archives of Internal Medicine, researchers examined the link between weight and risk of heart disease, using the body mass index (BMI) as a standard for comparison. Patients with a BMI less than 25 are considered normal weight, between 25 and 30 overweight, and greater than 30 obese.

The first study came from data extracted from National Health and Nutritional Examination Surveys, which examined 5,440 people between 1999 and 2004. In addition to determining whether participants were normal weight, overweight or obese, researchers also evaluated if they had two or more risk factors of heart disease, including high blood pressure, an elevated triglyceride, or a low level of the good, or HDL, cholesterol.

Twenty-three and a half percent of normal weight individuals were found to be at an increased risk of heart disease. Only 50 percent of overweight individuals were at increased risk of heart disease, compared to 69 percent of obese individuals. In other words, a significant fraction of overweight and obese people were "normal" and a large number of normal weight individuals were "abnormal" and at increased risk of heart disease.

Normal weight people who were at increased risk of heart disease tended to be older, less physically active and had higher waist circumferences than those who were at low risk. Overweight and obese individuals who were at low risk of heart disease were younger, black, more physically active and had smaller waists than those at high risk.

Another study conducted in Germany examined 314 people between ages 18 and 69. In addition to measuring their BMI, a magnetic resonance imaging (MRI) machine was used to measure abdominal, muscle and subcutaneous fat. In general, the overweight and obese people had more fat in their abdomen and muscles than those who were normal weight. Being overweight typically leads to an impaired ability of insulin to pump glucose into cells, a condition called insulin resistance.

However, in this study as many as 30 percent of the obese people did not have insulin resistance. Interestingly, these people had less fat in their muscles and in their livers than the 70 percent of overweight adults who did have insulin resistance. Furthermore, unlike those with insulin resistance, they had no evidence of deposition of fat in their carotid artery, which is a very sensitive marker of increased risk of heart disease and stroke. The researchers felt that these people had what they referred to as a "metabolically benign" form of obesity with a low risk of diabetes, heart disease and stroke.

Here is the message: Even if you are normal weight, there is a good chance that you are at increased risk of heart disease or diabetes. Just because a person is within the normal BMI range does not mean he lives a healthy life. If you are sedentary, smoke, have elevated blood pressures, high cholesterols or eat a poor diet, your risk of heart disease is high. Regardless of weight, if you maintain a high level of physical activity, normal cholesterol and a healthy diet, it is certainly possible to minimize the risk of heart disease.

These studies also show that more abdominal fat, as evidenced by a larger waist circumference, is a very sensitive measure of an increased risk of insulin resistance and heart disease. If you are shaped like an apple, your risk of heart disease is much greater than if you are shaped like a pear. If you have a very large belly, exercise, eat right and have regular medical check-ups, this can go a long way to assure that you too remain healthy for as long as possible.

No matter what the scale says, remember that we all must live a heart-healthy life. This will reduce your risk of disease and assure a longer and a better life.

Dr. David Lipschitz is the author of the book "Breaking the Rules of Aging." To find out more about Dr. David Lipschitz and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com. More information is available at www.drdavidhealth.com.

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