“Healthy” obese adults may be unable to maintain their metabolically healthy profile over time, according to a study published Jan. 5 in the Journal of the American College of Cardiology.

Using data from the Whitehall II cohort study of British government workers, researchers from the Department of Epidemiology and Public Health at University College London in England sought to examine the natural course of healthy obesity – defined as a lack of metabolic risk factor clustering in obesity – over two decades. Of the 2,521 participants ages 39 to 62 years old (75 percent male), 66 were healthy obese adults at baseline (measured in 1992 or 1994). While obese patients were defined as those with a body mass index as ≥ 30kg/m2, metabolically healthy patients were those with less than two of the following: high-density lipoprotein cholesterol level <1.03 mmol/l (men) and <1.29 mmol/l (women); blood pressure ≥ 130/85 mm Hg or use of antihypertensive medication; fasting plasma glucose level ≥ 5.6 mmol/l or use of antidiabetic medication; triacylglycerol level ≥ 1.7 mmol/l; and homeostatic model assessment of insulin resistance less than 2.87.

Researchers analyzed participants in the cohort study with data collected on obesity and metabolic status at baseline and follow-up examinations every five years. The results of the study showed that after five years, 32 percent of healthy obese participants were re-categorized as unhealthy obese. After 20 years (2012/2014), 52 percent of healthy obese at baseline were unhealthy obese, with only 10 percent measured at healthy non-obese. The study further shows that healthy obese adults were “eight times more likely to progress to an unhealthy obese state after 20 years than healthy non-obese adults.”

The authors note that the “natural course of healthy obesity is progression to metabolic deterioration.”

Lead study author, Joshua Bell, MSc, remarked, “healthy obese adults show a greater risk for developing cardiovascular disease than healthy normal-weight adults, although this risk is not as great as for the unhealthy obese... Healthy obesity is only valid if it is stable over time, and our results indicate that it is often just a phase. All types of obesity warrant treatment, even those which appear to be healthy. And as we now see, healthy obese adults tend to become unhealthy obese over time, providing further evidence against the idea that obesity can be healthy.”

Clinical Topics: Diabetes and Cardiometabolic Disease, Dyslipidemia, Hypertriglyceridemia, Lipid Metabolism

Keywords: Antihypertensive Agents, Blood Pressure, Body Mass Index, Cardiovascular Diseases, Glucose, Hypoglycemic Agents, Insulin Resistance, Lipoproteins, HDL, Obesity, Risk Factors, Triglycerides