Topical Area: Obesity, Aging and Chronic Disease
Previous research shows that variability in body weight is a significant predictor of health outcomes, including cardiovascular disease and future weight change. However, most studies use a limited number of intermittent data points (from 3-12) to estimate weight variability. Our study explored whether weight variability calculated from daily weights over 6 months predicted subsequent weight change and whether weight variability over one year differed by baseline BMI or gender.
Methods : We conducted a secondary analysis of the one-year weight data from our two-year randomized controlled trial of daily weighing. Intervention group participants (n=141) self-weighed daily, immediately after rising from bed in the morning, using an internet connected scale. This weight data was sent electronically to a server accessible to the research team. We used weight data from the first 6 months (median = 157 days of weights) or 12 months (median=295 days of weights) to calculate weight variabilities. Weight variability was defined as the root mean square error (RMSE) of the regression line of each participant’s weight trajectory over time. We conducted non-parametric correlations to explore the association of weight variability in the first 6 months with absolute weight change between 6 -12 months. Nonparametric correlations and ANOVA were used to explore the relationship between one-year weight variability and baseline BMI and gender, respectively.
Results : Participants were 42.9 ± 11.1 years of age (mean, SD), 75.9% women, 89.1% White, and 73.4% with Bachelor degree or higher. Median baseline BMI was 25.7kg/m2 (IQR= 23.2 to 30.1). Six-month weight variability was not associated with absolute weight change (lb) from 6 to 12 months (Spearman’s ρ= -0.06, p=0.49). Baseline BMI was positively associated with one-year weight variability (Spearman’s ρ= 0.60, p< 0.0001). One-year weight variability was higher in men (mean RMSE=1.92, SD=0.12) than women (mean RMSE=1.59, SD=0.07, p=0.014).
Conclusions : Among adults participating in a daily weighing study, early weight variability did not predict the magnitude of weight change within one year. Males and individuals with higher baseline BMI tend to have higher weight variability over one year.
Funding Sources : Division of Nutritional Sciences at Cornell University and National Institute for Food and Agriculture FCF Hatch Grant