Which fruit and vegetable skins are not advisable to eat?

Normally I eat the skins of most of the common fruits which can be eaten accept like the skins of banana, jack fruits, mango Li chi, etc. I also eat skins of most of the vegetable like potato, lemon, other common green vegetables. But I want to be sure about their safety and so need to no skins of which vegetable and fruits are not advisable for eating.