These results do not corroborate the assumption of a strong link between video gaming and body mass as respective associations are small and primarily observed among adults

Exploring the myth of the chubby gamer: A meta-analysis of studies on sedentary video gaming and body mass. Caroline Marker, Timo Gnambs, Markus Appel. Social Science & Medicine, June 9 2019. https://doi.org/10.1016/j.socscimed.2019.05.030

Highlights
•    Higher video gaming was positively associated with higher body mass.
•    The association was small in size, rho = .09, 95% CI [0.03, 0.14].
•    A significant link was found for adults but not for children or for adolescents.
•    We identified a small indirect effect for physical activity as a mediator.

Abstract
Rationale: High body mass and obesity are frequently linked to the use of sedentary media, like television (TV) or non-active video games. Empirical evidence regarding video gaming, however, has been mixed, and theoretical considerations explaining a relationship between general screen time and body mass may not generalize to non-active video gaming.

Objective: The current meta-analysis had two main goals. First, we wanted to provide an estimate of the average effect size of the relationship between sedentary video gaming and body mass. In doing so we acknowledged several context variables to gauge the stability of the average effect. Second, to provide additional evidence on processes, we tested the displacement effect of physical activity by video gaming time with the help of a meta-analytic structural equation model (MASEM).

Method: Published and unpublished studies were identified through keyword searches in different databases and references in relevant reports were inspected for further studies. We present a random-effects, three-level meta-analysis based on 20 studies (total N = 38,097) with 32 effect sizes.

Results: The analyses revealed a small positive relationship between non-active video game use and body mass,..., 95% CI [0.03, 0.14], indicating that they shared less than 1% in variance. The studies showed significant heterogeneity, Q (31) = 593.03, p < .001, I2 = 95.13. Moderator analyses revealed that the relationship was more pronounced for adults, , 95% CI [0.04, 0.40], as compared to adolescents, , 95% CI [-0.21, 0.23], or children, ..., 95% CI [-0.07, 0.25]. MASEM found little evidence for a displacement of physical activity through time spent on video gaming.

Conclusion: These results do not corroborate the assumption of a strong link between video gaming and body mass as respective associations are small and primarily observed among adults.