Is thick fruit skin safe to be eaten? There are kinds of fruit where it's common for people to eat the fruit together with the skin (apple, grapes etc.).  But there are some where people would peel off the skin beforehand like the kind of orange, banana, water melon etc. The skin does contain a heavy dose of fiber, and am wondering is it safe, or even healthy, to eat the skin?

But has anyone eat fruits such as orange or banana wholly without peeling off the skin, and find any health issue (positive or negative)? Assuming the skin is washed clean, do people peel skin because just it taste bitter?
this depends very much on:


the specific kind of fruit you're about to eat; 
Cultural normatives;
your personal flavor and preference;


For instance: I eat Avocados with the skin. Seriously. I do. Some of my friends consider it to be weird, but i couldn't care less - when they are ripe i just slice them as they are, stack 'em on a piece of bread and feast away with a sprinkle of salt. 

Most fruits i know of have edible skins - even citrus skin, as sour and zesty as it may be, is edible - and is used for producing all sorts of sweets, flavor extract and even food for animals.

I wouldn't go ahead and eat the skin of the Durian fruit - it's probably 'edible' but.... i donno.... it just doesn't feel right (plus the smell of it is UNBEARABLE)