Study summary: The current prospective study investigated the associations between physical activity, diet, and obesity and survival after breast cancer diagnosis. Study participants included 1,490 women diagnosed and treated for early-stage breast cancer between 1991 and 2000. The women were enrolled in the study at two years post diagnosis on average. Seven women were lost to follow-up through December 2005. In single-variable analysis, reduced mortality was found to be weakly associated with higher vegetable-fruit consumption, increased physical activity, and a body mass index that indicated neither low weight nor obesity. In a multivariate Cox model, only the combination of consuming five or more daily servings of vegetables/fruits plus accumulating at least 540 metabolic equivalent tasks-minutes per week (equivalent to walking 30 minutes, six days per week) was found to be associated with a significant survival advantage (hazard ratio, 0.56; 95% confidence interval, 0.31-0.98). The approximate 50% reduction in breast cancer metastasis risk associated with these behaviors was found in both obese and nonobese women, although fewer obese women were physically active with a high vegetable/fruit intake. In other words, among those who adhered to this healthy lifestyle, there was no observable effect of obesity on survival. The effect was stronger in women who had hormone receptor-positive (ER+/PR+) cancers.