Background:Lifestyle interventions are effective for weight loss and are recommended for persons with a body mass index (BMI) of 25–40 kg /m². However, this group is very heterogeneous, which could influence outcomes from lifestyle interventions. Purpose:In this systematic review, differences in 1-year weight change and percentage weight change after lifestyle interventions were investigated for participants varying in initial BMI using meta-analyses. Method:Twenty-two interventions with healthy Caucasian adults, a mean BMI between 25 and 40 kg /m², a dietary as well as a physical activity component aiming at weight loss, and at least five contact sessions guided by a professional health care provider were selected from a systematic search in the MEDLINE database. Participants in each intervention were divided into one of the three BMI classes: overweight (BMI of 25–29.99 kg /m²), class-I obesity (BMI of 30–34.99 kg /m²), and class-II obesity (BMI of 35–39.99 kg /m²). Differences in weight change and percentage weight change were analyzed and compared among different BMI classes within the same intervention by calculating standardized mean differences. Results:Overweight participants lost 1.1 kg less (p < 0.01) than participants with class-I obesity and 1.5 kg less (p < 0.01) than participants with class-II obesity. For percentage weight change, no significant differences were found among the BMI classes. Conclusion:Average weight change during lifestyle interventions only differs to a small extent among people with BMI between 25 and 40 kg /m². This implies that these interventions are equally appropriate for these BMI classes.