Complex sentence: Early in life, Dewey was diagnosed with megacolon, which was expected to shorten his lifespan, particularly as he refused to eat foods that would ease his condition, being a notoriously finicky eater.
Split into simpler sentences: Early in life, Dewey was diagnosed with megacolon, which was expected to shorten his lifespan. The condition was aggravated by his refusal to eat foods that would ease his condition, as he was a notoriously finicky eater.