AbstractThe aims of this study were twofold: (1) to investigate the effectiveness of web-based psychoeducation for emotional functioning, eating behaviors, and body image among premenopausal women with excess body weight, and (2) to compare the efficacy of two types of web-based psychoeducation. Three hundred individuals were asked to volunteer in the present study. All participants were recruited in Poland from September 2017 to July 2019. Finally, a total of 129 premenopausal women took part in the research and signed informed consent. Their ages ranged between 18 and 48 years old (M = 32.28, SD = 7.65). Self-reported weight and height were recorded. BMI was calculated using self-reported data. Their average body mass index was 30.54 kg/m² (SD = 3.69). In our randomized experiment, the participants were allocated into three groups: experimental group I (EG I, N = 43), experimental group II (EG II, N = 46), and wait list control group (CG, N = 40). Five questionnaires were included in the online survey at the baseline measurement (Day 0), at the end of psychoeducational intervention (Day 16) and 75 days from the start of the 15-day intervention (Day 76). Measurement tools included the Difficulties in Emotion Regulation Scale, the Positive and Negative Affect Schedule, the Mindful Eating Scale, the Three-Factor Eating Questionnaire, and the Body Attitude Test. Our eHealth web-based psychoeducation consisted of three modules: emotional functioning module (EG I: theoretically consistent approach (TCA) vs EG II: eclectic approach; EA), eating behaviors module (EG I, EG II: based on mindfulness-based eating training; MET), body image module (EG I, EG II: based on Cash’s prevention of body image disturbances; CPBID). The first experimental group (EG I) had intervention containing TCA, MET, and CPBID, while the second experimental group (EG II) EA, MET, and CPBID. According to between-group comparison, both types of web-based psychoeducation led to an increase in adaptive emotion regulation (Day 16: EG I vs CG: p < 0.001, EG II vs CG: p < 0.001; Day 76: EG I vs CG: p < 0.01, EG II vs CG: p < 0.001). In EG I, the intervention resulted in a higher reduction (than in CG) in emotional eating (Day 16: p < 0.01, Day 76: p < 0.01), uncontrolled eating (Day 16: p < 0.05, Day 76: p < 0.05), and negative appreciation of body size (Day 16: p < 0.01, Day 76: p < 0.01). In EG II, a lower level of emotional eating was found on Day 76 (EG II vs CG: p < 0.05). Two months after completion of the 15-day intervention, no statistically significant reduction for BMI was observed in either experimental group (p > 0.05). The effectiveness of both types of web-based psychoeducation was also confirmed in within-group comparison (Day 0 vs Day 16 and Day 0 vs Day 76). There was a significant increase in emotion regulation and mindful eating, as well as a decrease in emotional eating, uncontrolled eating, negative appreciation of body size, lack of familiarity with one’s body, and the experiencing of negative emotions in both experimental groups (EG I, EG II). Both types of web-based psychoeducation might have to be considered in creating future web-based psychoeducation among premenopausal women with excess body weight.