Metabolically healthy transition and its association with body size change patterns among different adult age groups

To explore the metabolically healthy (MH) to metabolically unhealthy (MU) transition and its association with body size change patterns according to age.

In total, 12,910 MH subjects were evaluated in 2013 and reevaluated in 2020. A MH state was defined as a score ≤ 1, and a MU state was defined as a score > 1 on the National Cholesterol Education Program-Adult Treatment Panel III criteria.

Approximately 27.0% of MH individuals converted to MU status over the follow-up. Compared with young adults, middle adulthood individuals had a 1.33-fold (95% CI: 1.21-1.46) and late adulthood individuals had a 1.55-fold (95% CI: 1.41-1.70) risk of transition. The body mass index (BMI)/waist circumference (WC)-value change was positively associated with metabolic deterioration; the association weakened with age. With stable normal body size (defined by BMI) as a reference, changing phenotype categories of maximum overweight [hazard ratio (HR): 1.75; 95% CI: 1.56-1.95], non-obesity to general obesity (HR: 2.96; 95% CI: 2.47-3.54) and stable general obesity (HR: 2.44; 95% CI: 1.92-3.10) conferred a higher risk of metabolic deterioration.

MH status is a transient state, especially in late and middle adulthood. Individuals transitioning to an obese phenotype should receive attention for concomitant metabolic deterioration.