How long does it take to develop abdominal muscles? Now I feel that my stomach is getting smaller every day, but I still have meat to eat, and I feel the muscles in my stomach every time I finish exercise. First of all, we should eat well and supplement protein, that is, eat more protein-rich foods such as eggs, fish, beef, mutton and milk. Then you should go to the gym 1-2 hours every day, do more flat support, ask the coach to teach you systematically, eat more protein powder, so that you can grow abdominal muscles in 3-4 months. I hope you can practice.