RE: How does a frutarian diet work? I've never really understood it from a nutritional perspective or really from a practical perspective either.

Response: Here is another view.  Some people that use the term frutarian, use the term in the botanical sense, meaning anything that contains a seed.  Using that definition, the list is a lot greater than just things like apples, bananas, melons, etc., the things we generally think of as fruit.  You may have actually eaten only 'fruit', but not everyone used the term the same way.

The botanical definition also includes tomatoes (who know where this one really fits), cucumbers, squash, etc., but not things like potatoes or carrots. Nuts and seeds may also be included. Generally speaking, this corresponds to things that grow on trees, vines, bushes, etc, but not in the ground (ie. the fruit of the plant, not the root of the plant).