Another source:
AltHealth http://www.althealth.co.uk/services/info/misc/polyols.php
"Since polyols are only partially absorbed by the body, they have fewer calories than sugar. Polyols range from 0.2 to 3 calories per gram, compared to sugar with 4 calories per gram."
For those who like to claim that the reason for some UK usage is that it comes from the United States, here is information on the owner of the site, a UK national (Wakefield, West Yorkshire, not Wakefield, Connecticut) who identifies the web designer as his son.