Physical activity and 4-year changes in body weight in 52,498 non-obese people: the Lifelines cohort.

Objectives: We investigated associations between leisure-time physical activity (LTPA) at different intensities (moderate and vigorous or moderate-to-vigorous) and prospective weight gain in non-obese people. We also examined whether these associations were independent of other lifestyle factors and changes in muscle mass and whether they were age-dependent and changed over a person's life course.

Methods: The data were extracted from the Lifelines cohort study (N = 52,498; 43.5% men) and excluded obese individuals (BMI > 30 kg/m). We used the validated SQUASH questionnaire to estimate moderate-to-vigorous (MVPA; MET≥4), moderate (MPA; MET between 4 and 6.5) and vigorous PA (VPA; MET≥6.5). Body weight was objectively measured, and changes were standardized to a 4-year period. Separate analyses, adjusted for age, educational level, diet, smoking, alcohol consumption and changes in creatinine excretion (a marker of muscle mass), were performed for men and women.

Results: The average weight gain was + 0.45 ± 0.03 kg in women. Relative to each reference groups (No-MVPA, No-MPA and No-VPA), MVPA (Beta (95%CI): - 0.34 kg (- 0.56;-0.13)), MPA (- 0.32 kg (- 0.54;-0.10)) and VPA (- 0.30 kg (- 0.43;-0.18)) were associated with less gain in body weight in women after adjusting for potential confounders, described above. These associations were dose-dependent when physically active individuals were divided in tertiles. Beta-coefficients (95%CI) for the lowest, middle, and highest MVPA tertiles relative to the 'No-MVPA' were, respectively, - 0.24 (- 0.47;-0.02), - 0.31 (- 0.53;-0.08), and - 0.38 (- 0.61;-0.16) kg. The average weight gain in men was + 0.13 ± 0.03 kg, and only VPA, not MPA was associated with less body weight gain. Beta-coefficients (95%CI) for the VPA tertiles relative to the 'No-VPA' group were, respectively, - 0.25 (- 0.42;-0.09), - 0.19 (- 0.38;-0.01) and - 0.20 (- 0.38;-0.02) kg. However, after adjusting for potential confounders, the association was no longer significant in men. The potential benefits of leisure-time PA were age-stratified and mainly observed in younger adults (men < 35 years) or stronger with younger age (women < 55 years).

Conclusion: Higher leisure-time MVPA, MPA, and VPA were associated with less weight gain in women < 55 years. In younger men (< 35 years), only VPA was associated with less weight gain.