© 2016, Springer-Verlag Berlin Heidelberg. Purpose: Comorbid medical conditions are common among breast cancer survivors, contribute to poorer long-term survival and increased overall mortality, and may be ameliorated by weight loss. This secondary analysis evaluated the impact of a weight loss intervention on comorbid medical conditions immediately following an intervention (12 months) and 1-year postintervention (24 months) using data from the Exercise and Nutrition to Enhance Recovery and Good health for You (ENERGY) trial—a phase III trial which was aimed at and successfully promoted weight loss. Methods: ENERGY randomized 692 overweight/obese women who had completed treatment for early stage breast cancer to either a 1-year group-based behavioral intervention designed to achieve and maintain weight loss or to a less intensive control intervention. Minimal support was provided postintervention. New medical conditions, medical conditions in which non-cancer medications were prescribed, hospitalizations, and emergency room visits, were compared at baseline, year 1, and year 2. Changes over time were analyzed using chi-squared tests, Kaplan-Meier, and logistic regression analyses. Results: At 12 months, women randomized to the intervention had fewer new medical conditions compared to the control group (19.6 vs. 32.2 %, p < 0.001); however, by 24 months, there was no longer a significant difference. No difference was observed in each of the four conditions for which non-cancer medications were prescribed, hospital visits, or emergency visits at either 12 or 24 months. Conclusions: These results support a short-term benefit of modest weight loss on the likelihood of comorbid conditions; however, recidivism and weight regain likely explain no benefit at 1-year postintervention follow-up.