Age-Specific Associations Between Adiposity and Mortality in U.S. Adults, 1999-2018 (JACC: Advances December 2025)-Article: iations Between Adiposity and Mortality in U.S. Adults, 1999-2018

Article: iations Between Adiposity and Mortality in U.S. Adults, 1999-2018

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This 2025 study analyzed data from 44,041 U.S. adults aged 18-79 over a median 10.1-year follow-up to examine how age modifies the association between adiposity and mortality. Using National Health and Nutrition Examination Survey (NHANES) data from 1999-2018 linked to mortality records through 2019, the researchers assessed multiple anthropometric measures: body mass index (BMI), waist circumference (WC), weight, and waist-to-height ratio (WHtR). They categorized adults into younger (18-49), middle-aged (50-69), and older (70-79) groups, and adjusted for demographic, behavioral, and clinical confounders.<br /><br />Key findings reveal significant age interactions: younger adults exhibited stronger associations between higher adiposity and increased all-cause and cardiovascular mortality compared to older adults. For instance, a one standard deviation (SD) increase in BMI correlated with a cardiovascular mortality hazard ratio (HR) of 1.49 in younger adults vs. 1.15 in older adults. Severe obesity (class 3, BMI ≥40) was linked to markedly elevated cardiovascular mortality risk in younger adults (HR 4.37) relative to older groups. Notably, underweight status was also associated with increased all-cause mortality, particularly in younger individuals (HR 2.04). Waist circumference and WHtR showed stronger mortality associations than BMI or weight, underscoring central adiposity’s role.<br /><br />The relationship between adiposity and mortality demonstrated a U-shaped curve across ages, with risks greatest at both low and high BMI extremes. However, the adiposity-mortality risk gradient diminished with age, potentially due to survivorship bias or competing mortality causes in older adults.<br /><br />These results highlight that both obesity and underweight confer disproportionate mortality risks among younger U.S. adults, emphasizing the importance of early, age-specific interventions to mitigate long-term cardiovascular and overall mortality risks. The study advocates increased focus on obesity prevention and treatment in younger populations, who often face healthcare access barriers, and attention to undernutrition causes. Limitations include observational design, exclusion of some confounders like diet and mental health, and limited inclusion of certain racial/ethnic groups.<br /><br />In conclusion, the study provides comprehensive, nationally representative evidence that age significantly modifies adiposity-mortality associations, underscoring the need for tailored public health strategies addressing both ends of the weight spectrum starting early in adulthood.

Keywords

adiposity

mortality

age modification

body mass index

waist circumference

waist-to-height ratio

cardiovascular mortality

obesity

underweight

NHANES