I never got sick since I quit early. I would most likely have gotten sick if I kept it up tho since I wasn't provided proper food.
The orphanage I lived at were too lazy to make proper vegetarian-friendly food for me (I was the only vegetarian living there at the time), so they'd usually just make "rabbit food" instead.
Before I ended up at the orphanage things were perfectly fine tho, since my family actually tried to support me and my choices.