The way I look at it is that food has always been unlimited apart from when I was a child - what I mean is, pre Slimming World no-one dished out a certain amount for me and I didn't weigh anything out - as adults, food and drink is ALL unlimited. The only difference now is that on SW, only the nutritious low-cal filling foods remain unlimited just as they were before but the higher cal lower filling foods ARE now limited. Personally, I put weight on because despite eating reasonably healthy meals, I had a few too many glasses of wine, bags of crisps etc, not because I didn't know when I was full, I just ate too much if the wrong things.
Also, with regard to the mullers eg, as far as I understand it, you'd have to eat 25 per day for a week to put on a lb so I don't think there's anything to worry about. Also, a muller or the much maligned banana eg are filling foods - much more than say a bag of crisps. I could eat 4 bags of crisps easily as they don't fill me up at all but I couldn't eat 4 bananas and if I did I'd be quite full!
I hope someone sees the logic in my ramblings lol! Xx