Objective: Several studies have demonstrated that daily physical activity (PA) prevents the development of breast cancer. Our objective was to examine the relationship between PA and clinical and biological tumor characteristics in breast cancer patients in order to determine the impact of energy expenditure (EE) on tumor prognosis. Methods: We pooled data from two prospective studies, including a total of 121 breast cancer patients. The measure of PA was done using the self-completion Population Physical Activity Questionnaire, which was answered by each patient. Results: Ten patients harbored triple negative (TN) tumors. The mean body mass index (BMI) in the general population and in patients with TN tumors was 24.3 and 25.6, respectively. The mean daily EE (DEE) was 10,266 kJ × 24 h-1 in the general population and 11,212 kJ × 24 h-1 in patients with TN tumors. In the whole population, there was an inverse statistical correlation between BMI and DEE, rest, low PA, and high PA (p = 0.0002, p = 0.003, p < 0001, and p = 0.03, respectively). There was a positive correlation between negative estrogen receptor status and intensive PA (p = 0.041) and DEE (p = 0.007). For TN tumors, there was no significant correlation between BMI and categories of EE. Conclusions: Lifestyle (weight regulation, PA) should be adapted and personalized according to biological, clinical, and epidemiological characteristics of the tumors.