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‘Healthy’ obesity likely to progress to unhealthy obesity
A new study challenges the concept of “healthy” obesity, with data demonstrating that most obese individuals become progressively less healthy with time.
“A core assumption of healthy obesity has been that it is stable over time, but we now see that healthy obese adults tend to become unhealthy obese in the long term, with about half making this transition over 20 years in our study,” Joshua Bell, MSc, researcher from the department of epidemiology and public health at University College London, said in a press release.
Bell and colleagues studied participants of the Whitehall II cohort study of British government workers with data on obesity and metabolic status at baseline (1992-1994) and follow-up examinations at 5 years (1997-1999), 10 years (2002-2004), 15 years (2007-2009) and 20 years (2012-2014). Their analysis included 2,521 adults aged 39 to 62 years at baseline, of whom 66 were classified as healthy obese (36.5% of the obese participants).
Obesity was defined as BMI of at least 30 kg/m. Participants who were classified as metabolically healthy had less than two of the following risk factors: HDL <1.03 mmol/L for men and <1.29 mmol/L for women; BP ≥130 mm Hg/85 mm Hg or the use of antihypertensive medication; fasting plasma glucose ≥5.6 mmol/L or the use of any antidiabetic medication; triacylglycerol ≥1.7 mmol/L; and insulin resistance >2.87.
According to the results, 21 (31.8%) of the healthy obese participants at baseline progressed to unhealthy obesity after 5 years, 27 (40.9%) after 10 years, 23 (34.8%) after 15 years and 34 (51.5%) after 20 years. The proportion of healthy obese adults who were nonobese at follow-up was reported in 6.1% after 5 years, 4.5% after 10 years, 6.1% after 15 years and 10.6% after 20 years.
When the researchers adjusted for age, sex and ethnicity, the prevalence of unhealthy obesity was 11.8 (95% CI, 7.28-19.11) after 5 years, 8.09 (95% CI, 5.54-11.81) after 10 years, 6.64 (95% CI, 4.43-9.96) after 15 years and 7.74 (95% CI, 5.53-10.85) after 20 years compared with healthy nonobese participants.
Additional analyses using different samples yielded similar results.
“Healthy obese adults were much more likely to become unhealthy obese than healthy or unhealthy nonobese adults, indicating that healthy obesity is a high-risk state with serious implications for disease risk,” Bell said.
“Healthy obesity is only valid if it is stable over time, and our results indicate that it is often just a phase,” he said. “All types of obesity warrant treatment, even those which appear to be healthy.”
Disclosure: Bell is supported by an Economic and Social Research Council studentship.