Weight gain is an important concern that impacts on breast cancer outcomes and general health in survivorship. This randomized, pilot study evaluated whether or not women could comply with a weight control program that is initiated at the beginning of chemotherapy for breast cancer. The program sought to prevent weight gain using a low-fat, high fruit-vegetable diet combined with moderate physical activity. The intervention was implemented using a telephone counseling approach that blended motivational interviewing with social cognitive theory. A total of 40 women were recruited over 9 months at the University of Michigan Comprehensive Cancer Center. This represents 55% of eligible women referred to the study and indicates that interest in a healthy lifestyle program at the initiation of chemotherapy for breast cancer was high. Subjects who dropped out had significantly lower fruit and vegetable intakes and lower blood carotenoids at baseline than subjects who completed the study. Statistically significant beneficial effects were observed on fruit and vegetable intakes, physical activity and breast cancer-specific well-being by the intervention. Mean body fat from dual energy X-ray absorptiometry increased in the written materials arm and decreased in the intervention arm. Of the enrolled women, 75% completed 12 months on study and satisfaction with study participation was high. These data indicate that lifestyle intervention during breast cancer treatment is feasible during treatment with chemotherapy for breast cancer and benefits women in several domains.