I probably shouldn't say this, but I never gave up coffee and I have lost over 100 pounds. Who knows, perhaps I would have lost if faster if I gave up the caffeine -- it took me 17 months. Coffee seems to be a real no-no for some people and it doesn't bother other people at all.

On the other hand, I have pretty much had to give up all artificial sugar (including Splenda) and there are a lot of people who don't have any problem with that.