Metabolically healthy overweight in young adulthood: is it a matter of duration and degree of overweight?

Abstract

Background and aim Given the controversy regarding metabolically healthy obesity, we studied the association between duration and degree of body mass index (BMI) from adolescence to early adulthood and metabolic status of both overweight/obese and under/normal weight subjects. Methods and results Participants of the EPITeen cohort were evaluated at 13, 17, 21 and 24 years (n = 1040). Duration and degree of BMI in the 11-year period was summarized through the area under the curve of BMI (BMIAUC). Metabolic health at 24 y was defined as optimal levels of lipids, blood pressure and glucose. The association between BMIAUC per year and metabolic health was estimated through binary logistic regression models, adjusted for confounders and stratified by BMI. The proportion of metabolically healthy overweight/obesity at 24 y was 13.4%. After adjustment for sociodemographic and behavioural factors, the increase of one kg/m2 in BMI on average per year during the period between 13 and 24 y was associated with 14% lower odds of being metabolically healthy among under/normal weight participants (OR = 0.86, 95% CI 0.78–0.94); and 8% lower odds of metabolic health among obese/overweight participants (OR = 0.92, 95% CI 0.85–1.00). After additional adjustment for waist circumference, the association was attenuated, especially in the obese/overweight group (OR = 1.03, 95% CI 0.93–1.14). About 20% of the metabolically healthy obese/overweight at 13 y transitioned to metabolically unhealthy obesity/overweight at 24 y. Conclusion The results support the hypothesis that the healthy obesity phenotype could be explained by a lower exposure to adiposity, either by shorter time or lower quantity, and a more favourable body fat distribution.