Posting this mostly expecting a critique of this diet, apparently there is an ultramarathoner who eats this way - I guess they get protein from seeds in the fruits, and mostly eat fruits and some veggies?
Again, personally I endorse this only as a temporary thing, I don't know how long it can be sustained for a lot of people. I think it overlaps with another religious fast that came up in discussion called "xerophagy", which is a raw fruits / veggies / seeds fast that I think it only supposed to be temporary for lent or maybe for committed religious people.
I am generally concerned with veganism as it can lead to various deficiencies. I think it can be healthy maybe spiritually, but a physically active lifestyle probably would benefit from meat consumption. I like veganism from a self-sufficienty perspective though, like it can take less resources to grow food than growing meat, but it seems like a trade off of health (which might be ok in certain circumstances if again done for spiritual reasons).
https://www.nomeatathlete.com/fruitarian-diet/
Surprisingly I've seen a few of these people pop up here and there online so I'm not sure how unsustainable the diet is at least short term (same with vegans). But I imagine deficiencies can develop long term.
Might be useful to know if in a survival situation with limited food, that maybe you can survive for a bit on some fruits, veggies, and seeds.