Complex sentence: Protein is described as essential by advocates of the high-protein diet, which includes a large proportion of the bodybuilding community; it is claimed to provide the muscle with amino acids required to repair the damage done by anaerobic exercise.
Split into simpler sentences: Protein is described as essential by advocates of the high-protein diet, a large proportion of the bodybuilding community. It is claimed to provide the muscle with amino acids required to repair the damage done by anaerobic exercise.