Abstract Body: Introduction: Metabolically unhealthy normal weight (MUNW) individuals exhibit metabolic abnormalities linked to obesity, increasing their risk of cardiometabolic diseases. MUNW is often overlooked in clinical practice, as guidelines generally focus on overweight or obesity. Additionally, the long-term stability of MUNW and its potential role in future weight gain remain unclear. This study aimed to identify factors associated with prevalent and incident MUNW and examine its stability over time.
Hypothesis: MUNW evolves into excess weight phenotypes, and among those with stable MUNW over time, the number of cardiometabolic risk factors (CRFs) increases.
Methods: We examined 2,343 individuals with normal weight (BMI ≥18.5, <25 Kg/m²) free of diabetes and cardiovascular disease (baseline) from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) [18-74 years old], a community-based cohort of Hispanic/Latino adults living in the U.S. MUNW was defined as having a normal weight with at least one of the following CRFs: elevated fasting glucose, triglycerides, blood pressure, or low HDL cholesterol. Survey multivariable models were used to explain prevalent and incident MUNW at baseline and after 7 years of follow-up. The stability of MUNW was assessed by tracking transitions to other weight phenotypes.
Results: At baseline, 69% of individuals had MUNW. In a multivariable model, older age [Odds Ratio (OR): 1.05, 95%CI: 1.03-1.06], being foreign-born with ≥10 years in the U.S. (vs. U.S.-born) [OR: 1.65, 95%CI: 1.17-2.33], and a household income over $40,000 (vs.<$20,000) [OR: 0.56, 95%CI: 0.39-0.81] were associated with prevalent MUNW. Waist circumference (continuous) was also associated [OR: 1.06, 95%CI: 1.03-1.08]. Among 264 individuals free of metabolic abnormalities at baseline who maintained normal weight over 7 years, 33.3% developed MUNW. Age [Relative Risk (RR): 1.04, 95%CI: 1.02-1.06] and male sex [RR: 1.76, 95%CI: 1.13-2.73] were predictors of incident MUNW. Among individuals with MUNW at baseline, 30.6% progressed to metabolically unhealthy overweight/obesity (MUO) and 3.7% to metabolically healthy overweight/obesity. Stable MUNW individuals (57.3%) showed an increase in the number of CRFs over time (p<0.05).
Conclusion: MUNW is not stable, as many individuals transition to MUO, and those remaining MUNW accumulate more CRFs over time. Metabolic health needs to be assessed in normal-weight adults, particularly those with high waist circumference.