The best exercise to lose bra fat is a combination of cardio and strength training. Cardio exercises such as running, swimming, cycling or walking can help burn calories and reduce overall body fat. Strength training helps build muscle in the chest area which can help tone the muscles around your bra line. Additionally, incorporating core exercises into your routine will help strengthen your abdominal muscles and give you better posture which can also make a difference in how much “bra fat” you have.