Bra fat can sometimes be caused by poor eating habits or muscle underdevelopment. Some research suggests that eating carbohydrates and refined sugars, especially when a person isn't hungry, can lead to an increase in abdominal fat. But, the majority of patients who have unwanted bra fat simply develop pockets of fat in this area of the body as a result of natural aging. Changes in metabolism and estrogen levels can influence how your body stores fat, and even patients who follow a healthy diet and exercise routine are quite often frustrated by excess fat in the bra area.