LAUSR

Background: Obesity is a heterogeneous condition, and there is debate about whether adults with “metabolically healthy obesity” (MHO) are protected from health complications. It is also unclear if MHO is a transient state. Objective: To examine transition from the MHO to metabolically unhealthy obese (MUO) phenotype during 6 years of follow-up among middle-aged adults. Methods: We conducted a prospective analysis of 9,672 adults in the ARIC Study who were free of cardiovascular disease (CVD) at Visit 2 (1990-1992) and attended Visit 4 (1996-1998). Obesity phenotypes were cross-classified using two body mass index subgroups 18.5-29.9 kg/m 2 (non-obese) and ≥ 30 kg/m 2 (obese). The NCEP Adult Treatment Panel III criteria were used to define metabolic health (without waist circumference). We used logistic regression to evaluate risk factors for transition from MHO at Visit 2 to MUO at Visit 4 among those with MHO at Visit 2(N=692). Results: At baseline (mean age 57, 21% black, 57% female), 18%, 54%, 7%, and 21% were metabolically healthy non-obese, metabolically unhealthy non-obese, MHO, and MUO, respectively. More adults with the MHO phenotype transitioned to MUO (48.3%) than maintained MHO status (43.4%) during the 6-year period). Most (71%) of those who transitioned from MHO to MUO were women. Adults with higher waist-to-hip ratio were more likely to transition to MUO (HR 2.67, 95% CI 1.09-6.58) than those who maintained their metabolic health during follow-up. (Table) . Conclusions: Almost 50% of adults who are MHO will transition to higher cardiometabolic risk over 6 years. High waist-to-hip ratio, lower socioeconomic status and smoking were linked to greater likelihood of transition to MUO. Persons with MHO should receive early behavioral interventions to prevent worsening metabolic health.