Physical sporting activity impact on long-term BMI trajectories in Dutch adults: a longitudinal observational study.

backgroundSporting activity is regarded as one of the key determinants of energy expenditure and is often recommended as a part of weight management. However, on a population basis the general long-term impact of initiating or modifying sporting activities on body mass index (BMI) remains insufficiently understood. This longitudinal study examines the relationship between sporting activity intensity, measured via metabolic equivalent task scores (MET), and BMI trajectories over a five-year period in a representative Dutch sample. Moderating effects of age, gender, and baseline BMI were assessed to identify population subgroups with differential responsiveness.

methodsData were drawn from the Longitudinal Internet Studies for the Social Sciences (LISS) panel (N = 6,337), which provided annual self-reported measures of BMI and sporting activities between 2008 and 2023. At baseline, the average age of participants was 47.1 years (sd = 17.0; median = 48.0) and 54.0% were female. Sporting activity intensity was operationalized using MET scores assigned to reported sport types. Linear mixed-effects models were used to evaluate the association between within-person changes in MET and BMI trajectories, adjusting for age, gender, and baseline BMI category. Interaction terms tested whether associations varied by obesity category and age group.

resultsCross-sectional analyses indicated that MET explained approximately 2% of the variance in BMI. Longitudinally, annual changes in sporting activity intensity were associated with only minimal but significant shifts in BMI for most participants. However, relevant effects emerged only in individuals with obesity (BMI ≥ 30). Specifically, starting to engage in a sporting activity with a MET rating of about 5 (such as moderate cycling) would be associated with an average annual BMI reduction of 0.3 points in individuals with class I obesity and 0.5 points for class II obesity. Among participants without obesity or those aged ≥ 65 years, BMI changes associated with MET variation were negligible. Gender did not significantly moderate the relationship.

conclusionsIn this large population-based sample from the Netherlands, sporting activity intensity showed a statistically significant but overall small impact on BMI trajectories, with the largest benefits concentrated in younger adults and individuals with obesity. These findings stress the importance of early and sustained engagement in higher-intensity sporting activities for weight management, while also pointing to the need for comprehensive strategies-including dietary interventions and medical options-for individuals with severe obesity or advanced age for whom high intensity sporting activities are not appropriate. Clinicians should provide realistic counselling about the expected magnitude of BMI change from sports alone and tailor recommendations to patients' weight status and functional capacity.