According to Dr. Oz, Being overweight has many negative consequences for health, and the risk of breast cancer is one of them. The effect of weight is dramatic. “For a woman who weighs over 175 pounds, the chances of breast cancer are about 25 percent higher than someone who weighs 132 pounds,” Dr. Oz says. “If there was a medication that gave us the same improvement as weight loss, we would be all over it.” Strive to keep your body mass index (BMI) under 25. Two more reasons to keep your weight in check: Breast cancer is often detected at a later stage in obese women, and obese women are more likely to die from breast cancer.