This thread got me thinking - I love pina coladas but almost never order them because they're really, really fattening. They're made with coconut milk which is a caloric disaster, plus lots of sugar. I froze some pineapple (I used canned because that's what I had on hand)then put some of that in the blender along with non fat yogurt and a little coconut extract. I added a few packets of Equal (sugar substitute) Well it came out delicious - very similar to a pina colada.   I experimented by making another one and adding a frozen banana to the mix and it came out even better. I didn't bother about adding alcohol because it's the creaminess, the frostiness and the flavor of the pineapple and coconut that I like, but I suppose you could add alcohol to the lo cal version.