The relationship between body weight, frailty, and the disablement process.

Objectives: To prospectively examine the relationship between body weight, frailty, and the disablement process.

Method: Longitudinal data from the Health and Retirement Study (1998-2006) were used to examine the relationship between being underweight, overweight, or obese (compared with normal weight) and the onset and progression of functional limitations and disabilities in instrumental activities of daily living (IADL) and activities of daily living (ADL) among a nationally representative sample of community-dwelling older adults (aged 50 and older) with characteristics of frailty (n= 11,491). Nonlinear multilevel models additionally adjusted for demographic characteristics and intra-individual changes in body weight, socioeconomic status, health behaviors, and health conditions over the course of 8 years.

Results: Compared with their nonfrail normal weight counterparts, prefrail obese respondents have a 16% (p ≤ 0.001) reduction in the expected functional limitations rate and frail overweight and obese respondents have a 10% (p ≤ 0.01) and 36% (p ≤ 0.001) reduction in the expected functional limitations rate, respectively. In addition, frail obese respondents have a 27% (p ≤ 0.05) reduction in the expected ADL disability rate.

Discussion: This study's findings suggest that underweight, overweight, and obese status differentially affect the risk for functional limitations and disabilities in IADL and ADL. Among prefrail and frail adults, some excess body weight in later life may be beneficial, reducing the rate of functional limitations and disability.