(2022) 22:1764 Bordeleau et al BMC Public Health https://doi.org/10.1186/s12889-022-14131-7 Open Access RESEARCH Body image and health‑related behaviors among fitspirit participants Manon Bordeleau1,2,3,4, Jo‑Anne Gilbert5,6, Natalie Alméras1,7, Johana Monthuy‑Blanc8,9, Joël Gagnon2, Marie‑Ève Mathieu5,6 and Vicky Drapeau1,2,3,4* Abstract Background: Body image variables such as body size perception (BSP) and body size dissatisfaction (BSD) can influ‑ ence health-related behaviors However, few studies have investigated these body image variables in adolescent girls participating in a physical activity intervention Therefore, the study objectives were to examine the 1) associations between health-related behaviors (physical activity, screen-time, eating habits and sleep duration) and BSP and BSD among girls participating in FitSpirit, a physical activity intervention for girls; and 2) influence of weight control prac‑ tices on the association between health-related behaviors and BSP and BSD Methods: This cross-sectional study assessed a sample of 545 adolescent girls (mean age: 15.0±1.5 years) from 240 schools Body mass index, health-related behaviors, perceived actual body size and desired body size variables were self-reported and collected via an online questionnaire at the end of the FitSpirit intervention A negative BSP score [perceived actual body size – calculated BMI z-score] indicates an underestimation of body size A positive BSD score [perceived actual body size – desired body size] indicates a desire to reduce body size A multiple linear regression analysis examined the effects of age, zBMI and health behaviors on BSP and BSD A second multiple linear regression analysis examined the independent associations between BSP and BSD by weight control practice The linear relation‑ ships between BSP and BSD were evaluated with Pearson’s correlations Results: Underestimation and dissatisfaction of body size are more prevalent in participants living with overweight/ obesity Screen-time and sleep duration were independently associated with BSP score (Beta=0.02; P