”Can obesity ruin our breasts? An increase in BMI is associated with a significant increase in breast cancer risk, although there are some differences in terms of age and menopausal status. In many studies, an association between overweight and obesity and breast cancer incidence has been found. Most studies and Meta-analyses have shown an increased risk of breast cancer in postmenopausal women and a negative association between obesity and prognosis of survival in breast cancer patients. The data on premenopause are still controversial. Several studies have shown that the risk of breast cancer decreases with increasing BMI (from 20 kg/m2) and that there is a linear relationship between them. On the other hand, for Asian populations obesity increases the incidence of breast cancer in premenopausal women. In addition, abdominal obesity and premenopausal risk of cancer are strongly associated. A retrospective study, clearly identified obesity as an independent predictor of distant metastasis and death in early breast cancer patients. Therefore, for postmenopausal women, obesity increases the incidence of breast cancer and weight loss, especially abdominal fat, is recommended. For breast cancer patients, weight loss improves prognosis and reduces recurrence and mortality of breast cancer and is recommended. For premenopausal women, obesity may reduce the incidence of breast cancer, but it is still controversial. Note: BMI (Body Mass Index, also known as Body Mass Index, or BMI for short) is a number derived by dividing weight in kilograms by height in meters squared, and is a commonly used international measure of body fatness and health.