While I don’t think these sweeteners are “unsafe” in the ways that many people worry about (concern that they cause cancer, for instance, is misplaced), I still don’t recommend using them.
Most are hundreds of times sweeter than sugar, and habitual use can turn your sweet tooth into a sweet fang.
So while you may cut calories by eliminating sugar in one area of your diet (for instance, by replacing regular soda with artificially sweetened diet soda), you’ll likely end up consuming more calories elsewhere— because you’ll crave sweeter dressings, sauces, breads, and so on. In fact, a 2008 animal study showed that eating artificially sweetened foods can actually lead to weight gain. For now, my advice is to consume fewer sweet foods and beverages overall—including those that use artificial sweeteners.
Source: David L. Katz, MD, oprah.com