Many studies have analyzed the possible association between the development of obesity and hormone levels, as well as their relation with the early development of breast cancer. As part of this study, we performed a retrospective collection of data from the clinical histories of 524 women in Granada (Spain), who had been diagnosed with breast cancer. The objectives were to verify an association between the nutritional state of the women and their age at breast cancer diagnosis as well as a possible relation between their nutritional state and seric levels of estrogens. The results obtained in this study show that obesity and the levels of certain hormones, such as estrogens, are closely associated with the early development of breast cancer.