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Greater functional, mobility declines in ‘healthy’ obesity vs. normal weight
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Adults with obesity considered to be metabolically healthy remain at increased risk for functional decline and disability vs. normal-weight adults, according to findings from a population-based study published in the International Journal of Obesity.
“Evidence so far on the outcomes of healthy obesity have been fairly narrow in scope, focusing mostly on cardiometabolic diseases,” Joshua A. Bell, PhD, a research associate in the MRC Integrative Epidemiology Unit at the University of Bristol, United Kingdom, told Endocrine Today. “Our findings suggest that healthy, obese adults tend to age faster than healthy, normal-weight adults by way of greater declines in functional status. Healthy obesity is not likely a protected state when it comes to risk for disability, and such outcomes that reflect day-to-day experience and quality of life need to be considered when advising healthy obese adults on weight loss.”
Bell and colleagues analyzed longitudinal data from 6,635 adults participating in the Whitehall II study, a group of London-based adults employed by the British government between 1985 and 1988 (mean age, 50 years; 70% men). Researchers assessed a combination of questionnaire and clinical data from eight repeated assessments during 2 decades (baseline in 1991-1994; follow-ups extending until 2012-2013). Participants were classified as normal weight (BMI, 18.5-24.9 kg/m²), overweight (BMI, 25-29.9 kg/m²) or obese (BMI 30 kg/m²), and were considered to be metabolically “healthy” if they had none or one of five metabolic risk factors: Low HDL cholesterol or use of lipid-lowering medication; high blood pressure or use of antihypertension medication; fasting plasma glucose of at least 5.6 mmol/L or use of antidiabetic medication; triglyceride level greater than 1.7 mmol/L or homeostatic model of insulin resistance (HOMA-IR) measurement greater than 3.2.
Assessment of physical function was based on a subdomain of the Short Form Health Survey, as was assessment of bodily pain; summary scores for each of the physical function and bodily pain measurements were used to estimate change over time. Mobility and disability assessment was assessed on three occasions via walking tests and questionnaires regarding activities of daily living.
Within the cohort, 3,339 were normal weight and 80.5% of those were considered metabolically healthy; 2,634 adults were overweight and 56.3% were considered metabolically healthy; 662 adults were obese and 34% were considered metabolically healthy.
After adjustment for demographic factors, occupational position and health behaviors, metabolically healthy adults with obesity experienced a decline in physical function of –3.48 score units per decade (95% CI, –4.88 to –2.08), which was nearly two times greater than that among healthy, normal-weight adults, according to the researchers. The greatest decline in physical function was observed in unhealthy adults with obesity, who experienced a decline of –5.02 score units per decade (95% CI, –6.06 to –3.98) vs. healthy, normal-weight adults; however, this was not greater than for healthy adults with obesity (P = .068).
Researchers also observed a worsening of bodily pain score among all metabolic and obesity groups during follow-up, with the greatest increase in pain observed in healthy adults with obesity vs. healthy, normal-weight (difference in 10-year change, –2.23 units; 95% CI, –3.78 to –0.69), after adjustment for social and behavioral factors.
When assessing mobility limitation during a mean observation period of 8.3 years, researchers found that healthy adults with obesity had 3.39 higher odds of having a mobility limitation over follow-up vs. healthy, normal-weight adults (95% CI, 2.29-5.02), after adjustment for social and behavioral factors.
When assessing odds for disability, healthy adults with obesity were 3.75 times more likely to be disabled during a mean follow-up time of 5.6 years vs. healthy, normal-weight adults (95% CI, 1.94-7.24)
“Clinicians need evidence on a range of outcomes when deciding whether to advise patients who are obese, yet metabolically healthy, on weight loss,” Bell said. “Our findings suggest that when it comes to functional impairment, there is little reason to provide different advice to adults with obesity based on whether or not they appear metabolically healthy. Both groups carry high risk.”
Bell added that as more people with obesity live longer, such functional outcomes that threaten independence will become increasingly important.
“Future studies could make use of data on genetic variants associated with markers of adiposity and metabolic health, to compare the causal effects of these exposures on musculoskeletal conditions, like osteoarthritis,” Bell said. “This allows a sort of naturally occurring, randomized trial in population samples and can help identify the best targets for intervention. These studies are challenging, however, as they require robust genetic data on large numbers of people.” – by Regina Schaffer
For more information:
Joshua A. Bell, PhD, can be reached at the MRC Integrative Epidemiology Unit at the University of Bristol, Senate House, Tyndall Avenue, Bristol, BS8 1TH, United Kingdom; email: j.bell@bristol.ac.uk.
Disclosure: The researchers report no relevant financial disclosures.
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