I used artificial sweeteners throughout my weight loss and successfully lost over 100 pounds drinking diet soda, putting splenda in my coffee and eating diet pudding with sweetener. However, I've begun reducing my use of artificial sweeteners, because unlike products like caffeine and wine, which are sometimes found to be good for us and other times found not to be so good, I've never seen a research study that shows that artificial sweeteners are good for our health.
That said, it's difficult for research to pinpoint them as a cause of weight gain in humans. In fact, in the first article linked to on this thread, the statement was made: "research has repeatedly demonstrated that artificial sweeteners actually make you gain equal or more weight than regular sugar." I don't know that any of the studies they cited actually show that. Several of the references were about artificial sweeteners ability to increase hunger, not weight gain. Another looked at the relationship between sweetener use and consumption of sugar (finding different results for men and women). The last article discussed a correlation between consumption of artificial sweeteners and weight gain, but that doesn't demonstrate causality. So I am having trouble taking the rest of the article seriously, especially as it seems to use scare tactics ("think formaldehyde"). That said, I have seen a number of credible studies showing how these sweeteners don't necessarily fool us as well as we think they should, so I do think there's something to that piece of it. It's one of the reasons I've been cutting it from my diet.
So I'm not saying people should or should not use artificial sweeteners. But I am saying that it's difficult to do definitive research in human on and I'm not sure there's good evidence to show that the sweeteners cause weight gain. There may be other reasons not to use it, however.
My 5 C's of healthy living: Commitment to conscious control, with the understanding that choices have consequences