To personalize lifestyle advice for women with polycystic ovary syndrome (PCOS) and obesity, detailed information regarding dietary intake, eating behavior, physical activity levels, and quality of life (QoL) may be useful. We aimed to investigate in a post-hoc cross-sectional analysis within a large multicenter randomized controlled trial in women with infertility whether there are significant differences in dietary intake (vegetables, fruits, sugary drinks, alcoholic beverages, savory snacks, and sweet snacks); eating behavior (emotional eating, external eating, and restricted eating); physical activity; and QoL between women with PCOS and obesity and non-PCOS obese controls. Participants were asked to complete the food frequency questionnaire (FFQ), the Dutch Eating Behavior Questionnaire (DEBQ), the Short QUestionnaire to ASsess Health-enhancing physical activity (SQUASH), and the 36-item Short Form Health Survey (SF-36) at study entry (PCOS: n = 170; non-PCOS: n = 321, mean BMI: 36). Linear and binary (multinomial) logistic regressions were used, and the analyses were adjusted for age, waist–hip circumference ratio, and homeostasis model assessment of insulin resistance (HOMA-IR). No statistically significant differences in dietary intake or physical activity were observed between the two groups. The overall score of emotional eating was 34.6 ± 11.2 in the PCOS group and 34.1 ± 11.3 in the non-PCOS group (p = 0.11). QoL scores (physical and mental) did not differ between PCOS and non-PCOS women. These findings suggest that infertile women with PCOS and obesity and infertile non-PCOS obese controls do not have different dietary habits and have similar mental and physical QoL.