There are three types of muscles in the human body: Skeletal Muscle, Smooth Muscle and Cardiac Muscle (heart muscle).
Among them, we focus on the weight gain of skeletal muscles only.
Skeletal muscles contain approximately 75% water, 20% protein, 1–10% fat, and 1% glycogen. [Section-3]
From these facts, if I kept the water aside. Then is it only the protein that is required for muscle growth? Since fat and glycogen are in minor amounts, discard them. Am I missing anything? I mean are there any other sources to build muscle gain along with protein?