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

<bold>Objective: </bold>To explore the metabolically healthy (MH) to metabolically unhealthy (MU) transition and its association with body size change patterns according to age.<bold>Methods: </bold>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.<bold>Results: </bold>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.<bold>Conclusions: </bold>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. [ABSTRACT FROM AUTHOR]