Fruit has a lot of sugars, tho it’s a natural way to get sugar that comes with other nutrients attached, it’s still sugar. I can’t quote a source but have seen it said that a study showed that 2 servings or more of fruit per day can come with a higher risk of diabetes and Alzheimer’s. Fruit also carries a higher pesticide load than many other foods.

Probably the most famous fruititarian was Steve Jobs who died young age 56 from neuroendicrine cancer. I’m not saying fruit is unhealthy, it’s a great thing to have in moderation such as a serving or two in a day.. but eating only fruit I feel is extreme and likely to lead to problems. It’s like, one step away from breathitarians.

You need other nutritional building blocks like veggies and good protein and healthy fat sources like olives and avocado to sustain good health. You can manage to get protein as a vegetarian if you won’t eat animal products by utilizing beans and maybe eggs.