Not everyone who carries excess weight is at increased risk of developing cardiovascular disease.  In fact, it’s possible to be clinically obese and have a heart as healthy as a person of normal weight.  And many people of normal weight bear a greater chance of developing cardiovascular disease than some of their heavier counterparts do, according to two studies published in this week’s issue of the Archives of Internal Medicine, a publication of the Journal of the American Medical Association (JAMA).

Norbert Stefan, MD, and his colleagues working from Germany’s University of Tubingen, analyzed the distribution of body fat in 314 individuals whose average age was 45.  Each participant underwent a magnetic resonance tomography to locate body fat, including visceral and subcutaneous fat.  Visceral fat accumulates mainly in the abdominal cavity around the internal organs while subcutaneous fat is found just under the skin.  An oral glucose tolerance test measured each participant’s level of insulin resistance.

All study participants were placed in one of four groups – those of normal weight, those who were overweight, those who are obese but sensitive to insulin, and those who are obese but suffer from insulin resistance.

The overweight group and the two obese groups had more overall body fat and visceral fat than the normal-weight group.  Of the two obese groups, the insulin-resistant group had more fat in the liver and skeletal muscles than the obese group without resistance to insulin.  The insulin-resistant group also had carotid arteries with thicker walls, an early symptom of narrowing of the arteries, a form of atherosclerosis that can increase the risk of developing heart disease.  The obese group without insulin resistance had artery walls no different than the group of normal weight, meaning they were overweight but not at increased risk of developing cardiovascular disease.

The research team says the fatty accumulation around the liver may be a more important factor than the other visceral fat for determining the degree of risk in an overweight individual.  Describing the insulin-sensitive obese group as metabolically benign, the researchers say this group’s risk of developing cardiovascular disease is no greater than that of the group of individuals of normal weight.

Rachel P. Wildman, PhD, and her team of researchers explored the metabolic health of 5,440 adults as a means of determining how prevalent cardiometabolic abnormalities are in the general population.  Cardiometabolic abnormalities include elevated triglycerides, low levels of high-density lipoproteins (or, the good, HDL, form of cholesterol), blood pressure, and weight.  For the sake of the study, a person was considered metabolically healthy when no more than one cardiometabolic abnormality was present.

The findings reveal:

• 23.5% of all US adults of normal weight aged 20 or older are metabolically abnormal
• 51.3% of all US adults who are overweight and aged 20 or older have no metabolic abnormalities, meaning they are metabolically healthy
• 31.7% of all US adults who are obese at age 20 or older are metabolically healthy

The researchers conclude that weight is no indication of metabolic health, as many people of normal weight are not healthy on a metabolic level while many people who carry excess weight do so and still remain metabolically healthy.

Source: JAMA