Predicting Change in Physical Activity: a Longitudinal Investigation Among Weight-Concerned College Women

Background: Engaging in regular physical activity (PA) is critical for health, and adopting a consistent PA routine early in life is associated with greater PA over the lifespan. College women with weight concerns are at risk for weight gain, which may be prevented with regular PA. However, little is known about changes in PA engagement in this at-risk group. Purpose: Using an outcome expectancy framework, this study used a prospective longitudinal design to examine changes in PA during the first 2 years of college. We tested for concurrent and prospective within-person relations between body satisfaction/perceived eating behavior and PA to determine when weight-concerned college women may increase or decrease PA. Methods: Women who reported weight concerns at the start of college (n = 294) completed five assessments over 2 years, including measured weight, body/eating experiences, and 4 days of pedometer steps (per assessment). Multilevel models addressed the resulting nested data structure (days within assessments within participants). Results: Over 2 years, within-person change accounted for 65 % of PA variability (ICC = 0.35). PA was greatest at (and subsequent to) times when body satisfaction was lower, and when disinhibited eating and hedonic hunger were higher, than an individual’s average (ps < 0.05). These changes were associated with 1–3 % of the recommended daily step totals. Conclusions: Weight-conscious college women show greater PA after negative eating and weight experiences. As these experiences change over time, health promotion efforts should help college women identify alternative, positive motivators for PA, which could facilitate consistent PA engagement.