What are sugar-free sweets actually made from? I was eating a sugar-free "Polo mint" the other day and the question popped into my mind "So, if this isn't sugar.... what is it??"

I understand they use an artificial sweetener (Sorbitol), and Magnesium Stearate as a lubricant, but these don't explain what is the BULK of the sweet actually made from? 

A Google session came up with a lot of people asking this question (about sugar free sweets in general) but no solid (!) answers.
It appears that he main ingredients of sugar free Polo Mints are:


Sorbitol - a non-sugar (technically a sugar alcohol) sweetener with less calories per gram than sucrose, about 2.6 kilo-calories per gram compared to sugar's 3.9.  E420 in Europe.
Magnesium stearate - this appears to not be metabolizable.  E470b in Europe.
Mint oils


I did a quick check of UK labeling laws, and it appears all ingredients must be listed.

So the answer is:  the sugar substitute itself, sorbitol provides some of the bulk of the candy, with most of the rest being the magnesium stearate.