Eating large volumes of food will stretch and workout muscles of stomach. Regardless of calories the volume of food might associate with different workouts of stomach.
Many Surgeries block regular stomach stretching of muscles and weakens muscle tissue of digestive system. Vegetables are healthy foods to work out stomach muscles. Fatty food has enormous calories in very little volumes, foods rich in fat/oil will not workout muscles of stomach.
Not eating enough protein (amino-acid) will weaken any muscle including stomach muscle. Healthy stomach muscle will maintain healthy appetite. Strong upper body ligaments, neighbor muscles will improve strong muscle stomach muscles.
Stretching of muscles increases turn over in muscle tissue, burns unhealthy fat in muscle tissue.
