Abstract Objective The majority of endometrial cancer survivors (ECS) are obese and at risk for premature death. The purpose of this study was to assess feasibility of a lifestyle intervention program for promoting weight loss, change in eating behaviors, and increased physical activity in obese ECS. Study design Early stage ECS ( n = 45) were randomized to a 6-month lifestyle intervention (LI; n = 23) or usual care (UC; n = 22). The LI group received group and individual counseling for 6 months. The primary endpoint was weight change. Secondary endpoints were physical activity, [Leisure score index (LSI)] and nutrient intake (3-day food records). Quantitative vitamin C and folate intake were used to assess fruit/vegetable intake. Results Recruitment was 29%, adherence (LI group) was 73% and 84% of participants completed follow-up assessments. At 12 months, the intervention group lost 3.5 kg compared to a 1.4 kg gain in the control group [mean difference = − 4.9 kg; 95% CI: − 9.0 to − 0.9 kg; p = .018] and had an increased LSI score of 16.4 versus − 1.3 in the control group from baseline [mean group difference = 17.8; 95% CI = 7.1 to 28.4; p = .002]. There were no differences in vitamin C and folate intake. The LI group had lower intake of kilocalories, although differences were not significant. Conclusion(s) A lifestyle intervention program in obese ECS is feasible and can result in sustained behavior change and weight loss over a 1-year period.