ABSTRACT: Weight gain and metabolic changes have been related to survival of early breast cancer patients (EBC). ''However, factors influencing metabolism post-diagnosis are not fully understood. We measured anthropometric [body mass index (BMI), body weight, waist and hip circumferences, and waist-to-hip ratio] and metabolic (levels of insulin, glucose, H1Ac, total, HDL, and LDL cholesterol, triglycerides, and the homeostasis model assessment score [HOMA]) parameters in 433 pre- and post-menopausal women with EBC at diagnosis and 3, 6, 9, 12, and 24 months thereafter. At diagnosis, compared with post-menopausal women, pre-menopausal patients were more likely to be leaner and to have a lower BMI, smaller waist and hip circumferences, and waist-to-hip ratio. They had also lower glucose, HbA1c, and triglyceride levels and a lower HOMA score. Furthermore, they were more likely to have an estrogen- and/or progesterone-positive tumor and a higher proliferating breast cancer. During the first two post-diagnosis years, all women showed a significant increase of weight (+0.72 kg/year, P < 0.001), waist circumference (+1.53 cm/year, P < 0.001), and plasma levels of LDL cholesterol (+5.4 mg/dl per year, P = 0.045) and triglycerides (+10.73 mg/dl per year, P = 0.017). In patients receiving chemotherapy only, there was a significant increase in hip circumference (+3.16 cm/year, P < 0.001) and plasma cholesterol levels (+21.26 mg/dl per year, P < 0.001). We showed that weight, body fat distribution, and lipid profile changed in EBC patients receiving adjuvant therapy. These changes occurred during the first 2 years after diagnosis and were not specifically related to chemotherapy, menopausal status, or initial body weight.