Every muscle is connected together, hehe ~ they are all together when practicing. The latissimus dorsi works with the triceps brachii, and the pectoralis major works with the rectus abdominis and abdominal muscles. Find an effective gym tour coach who can tell you the diet and fitness plan. If you are not fat, you should eat less but more times, such as 6 meals a day, and eat foods and fruits with high content in protein. Breast milk is not reliable, but it's ok. After all, milk is mainly made up of protein.