ESC 2012 Report – Metabolically healthy, fit obese persons appear to have normal CVD and cancer risks

by Bruce Sylvester – Obese persons who are metabolically healthy and fit have no more risk of developing or dying from cardiovascular disease or cancer than persons of normal weight, researchers reported in the largest study to date on the subject. The findings appeared online on Sept. 4, 2012 in the European Heart Journal .

The investigators identified a subset of obese persons who are unaffected by conditions such as insulin resistance, diabetes and high cholesterol or blood pressure, and who have achieved a higher level of fitness, measured by heart and lungs performance, than other obese people.

They found that obesity alone does not appear to be detrimental to their health

“It is well known that obesity is linked to a large number of chronic diseases such as cardiovascular problems and cancer. However, there appears to be a sub-set of obese people who seem to be protected from obesity-related metabolic complications,” said investigator and author,  Francisco Ortega, PhD, research associate at the Department of Physical Activity and Sport, University of Granada, Spain. “They may have greater cardio-respiratory fitness than other obese individuals, but, until now, it was not known the extent to which these metabolically healthy but obese people are at lower risk of diseases or premature death.”

Data was extracted and analyzed from the long-running “Aerobics Center Longitudinal Study” (ACLS) based at the University of South Carolina, Columbia, South Carolina. The study  provided 43,265 subjects for this analysis.

Subjects were enrolled in ACLS between 1979 and 2003. They completed a medical and lifestyle history questionnaire, a physical examination, a treadmill test to assess cardio-respiratory fitness, measurements of height, weight, waist circumference, and measure of percentage of body fat. Investigators also measured blood pressure, cholesterol and fasting glucose.

Subjects were tracked until they died or until the end of 2003.

Ortega and his team reported that 46% of the obese subjects were metabolically healthy. After adjusting for several confounding factors, including fitness, metabolically healthy but obese subjects achieved a 38% lower risk of death from any cause than metabolically unhealthy obese subjects. The investigators reported no significant difference in overall mortality risk between the metabolically healthy obese subjects and the metabolically healthy, normal weight subjects.

They also found that the risk of developing or dying from cardiovascular disease or cancer was  30-50% lower for the metabolically healthy obese subjects compared to metabolically unhealthy subjects, and there were no significant differences between the former and metabolically healthy, normal weight participants.

Ortega said, “Physician should take into consideration that not all obese people have the same prognosis. Physician could assess fitness, fatness and metabolic markers to do a better estimation of the risk of cardiovascular disease and cancer of obese patients. Our data support the idea that interventions might be more urgently needed in metabolically unhealthy and unfit obese people, since they are at a higher risk. This research highlights once again the important role of physical fitness as a health marker.”