Longitudinal association between body mass index and handgrip strength in community-dwelling older adults: a population-based nationwide cohort study

Weakened handgrip strength is now a major public health concern. The relationship between body mass index (BMI) and handgrip strength (HGS) is controversial and inconclusive. We conducted cross-sectional and longitudinal analyses to investigate the association between BMI and HGS in middle-aged and older Chinese population. We conducted a population-based cohort study using nationally representative data from the China Health and Retirement Longitudinal Study (CHARLS). A total of 5741 participants aged ≥ 60 years old at the baseline survey of CHARLS (2011) were included and a total of 2877 participants without low HGS were followed up in 2015. Multivariate linear and logistic regression models were constructed to evaluate the associations of BMI with HGS. The BMI was positively associated with HGS (β = 0.11; 95% CI: 0.07–0.15). During the 4 years of follow-up, 912 cases (31.7%) with low HGS were identified. Underweight BMI (OR: 1.56; 95% CI: 1.15–2.12) was significantly associated with increased risk of low HGS compared to the normal weight, while overweight (OR: 0.67; 95% CI: 0.55–0.83) and obesity (OR: 0.67; 95% CI: 0.50–0.91) were significantly associated with reduced risk of low HGS. Such associations were robust in subgroup analysis. Significant non-linear dose–response relationship between BMI and low HGS was also observed. Our findings revealed that underweight BMI might be a predictor of low HGS in older adults, representing an important at-risk group for screening and intervention, and maintaining a higher BMI might prevent the development of low HGS in this population.