Arnold Ehret, who lived in the early 20th century, was one of the biggest fruitarian influencers. He was also in excellent physical shape, and was able to reverse chronic disease with his lifestyle. Most of today's fruitarians are direct or indirect "disciples" or followers of his teachings.

He's written several books, and I've read two of them: one, on fasting, a fascinating book, the other one, about what he termed "the mucusless healing diet system" where he advocates for a fruitarian diet and fasting regularly to "cleanse" the body. He was against meat consumption, that he claimed causes mucus formation (inflammation) in the body.

He was a bit of an "extremist" with fringe ideas, and in a way reminds me of today's carnivore advocates who claim that plants are toxic for the body and should be avoided.