Individual changes in anthropometric measures after age 60 years: a 15-year longitudinal population-based study

weight loss is commonly observed with ageing. We explored the trajectory of body mass index (BMI) and two proxies of muscle mass-calf circumference (CC) and mid-arm circumference (MAC)-and identified their determinants.

within the SNAC-K cohort, 2,155 dementia-free participants aged ≥60 years were followed over 15 years. BMI, CC and MAC were measured at baseline and follow-ups. Baseline sociodemographic and lifestyle factors were collected through interviews. Diabetes and vascular disorders were diagnosed by physicians through clinical examination and medical records. Data were analysed using linear mixed-effect models stratified by age (younger-old [<78 years] vs. older-old [≥78 years]).

over the 15-year follow-up, BMI remained stable among participants aged 60 years at baseline (βslope = 0.009 [95% confidence interval -0.006 to 0.024], P = 0.234) and declined significantly among those aged ≥66 years, while CC and MAC declined significantly across all age groups. The decline over 15 years in BMI, CC and MAC separately was 0.435 kg/m2, 1.110 cm and 1.455 cm in the younger-old and was 3.480 kg/m2, 3.405 cm and 3.390 cm in the older-old. In younger-old adults, higher education was associated with slower declines in all three measures, while vascular disorders and diabetes were associated with faster declines. In older-old adults, vigorous physical activity slowed declines in BMI and CC, while vascular disorders accelerated declines in BMI and MAC.

CC and MAC declined earlier and more steeply than BMI. Cardiometabolic disorders accelerated such declines, while higher education and physical activity could counteract those declines.