I'm strictly strong espresso/macchiato, self-ground fresh beans, and drink 3 or 4 doubles most mornings. Last time I stopped was for 6 weeks mid last year as an experiment. No effects whatsoever that I could discern. Nothing you'd really call cravings either. I did want coffee in the first few mornings, but missed it less than I did apples when floods disrupted supply of most fresh goods here last year.

So I guess there really must be individual differences.