I... I'm honestly at a loss for words. If someone things that would be a good thing to do I think you just need to let them do it, I don't know if you could talk sense into them.

+1....seriously either or.

Could someone describe what might happen if one has been following a low carb, high fat diet and would like to do a "watermelon cleanse"...for 1 or 2 days ( where you only ate watermelon?).  This is NOT for me but for a friend who thinks it would be a good "digestive rest" and would like to do a mono diet of watermelon for 1-2 days.....what kind of negatives would happen here?  Would like to explain but have no idea.  Thanks

It would be turrible. Watermelon  is like 99% sugar. And it's pretty high on the GI charts.  So just ingesting this would cause massive blood glucose fluctuations throughout the course of the day.  Potential hypoglycemic effects from the crash.  If they want "digestive rest",  switching  to homemade foods without preservatives and finding any gluten / dairy intolerance would be the way to go.  Sent from my SCH-I535 using Tapatalk

Or just tell them to fast for 24-36 hours...

I know that she used to be a "fruitarian" and lived on 80% fruit and 10% vegetable.  She got SO skinny...perhaps she might think that eating just watermelon will be a easy way to get "skinny" but no realizing the muscle loss that would take place.  People who take up this fruitarian lifestyle seem so skinny and lose so much weight...im assuming its all muscle?

They lose fat to, but yes, they lose muscle and bone density. They are unhealth, fragile, a hormonal wreck most of the time.