Abstract
This study aims to investigate the association between metabolomic aging acceleration and body mass index (BMI) phenotypes with mortality and obesity-related morbidities (ORMs). 85,458 participants were included from the UK Biobank. Metabolomic age was determined using 168 metabolites. The Chronological Age-Adjusted Gap was used to define metabolomically younger (MY) or older (MO) status. BMI categories were defined as normal weight, overweight, and obese. Participants were categorized into MY normal weight (MY-NW, reference), MY overweight (MY-OW), MY obesity (MY-OB), MO normal weight (MO-NW), MO overweight (MO-OW), and MO obesity (MO-OB). Mortality and 43 ORMs were identified through death registries and hospitalization records. Compared with MY-NW phenotype, MO-OB phenotype yielded increased risk of mortality and 32 ORMs, followed by MO-OW with mortality and 27 ORMs, MY-OB with mortality and 26 ORMs, MY-OW with 21 ORMs, and MO-NW with mortality and 14 ORMs. Consistently, MO-OB phenotype showed the highest risk of developing obesity-related multimorbidities, followed by MY-OB phenotype, MO-OW phenotype, MY-OW phenotype, and MO-NW phenotype. Additive interactions were found between metabolomic aging acceleration and obesity on CVD-specific mortality and 10 ORMs. Additionally, individuals with metabolomic aging acceleration had higher mortality and cardiovascular risk, even within the same BMI category. These findings suggest that metabolomic aging acceleration could help stratify mortality and ORMs risk across different BMI categories. Weight management should also be extended to individuals with overweight or obesity even in the absence of accelerated metabolomic aging, as they face increased healthy risk compared with MY-NW individuals. Additionally, delaying metabolic aging acceleration is needed for all metabolomically older groups, including those with normal weight.