Why are gasoline and similar hydrocarbons poisonous but animal/vegetable fats are not?

[ewmon]

I'm okay in biochemistry but not great, so I need someone more knowledgeable to help here.

 

Both gasoline/hydrocarbons and animal/vegetable fats contain mostly long strings of hydrocarbons, although fats also contain a glycerol or other molecule. Cells even have walls composed of a lipid bilayer.

 

So, as the title states, what is it about gasoline/hydrocarbons that make them poisonous while animal/vegetable fats are not?

 

First glance shows that they differ due to a glycerol or other non-hydrocarbon molecule, yet if that's the reason, how does the presence of this type of molecule cause fats to be non-poisonous?