Psychologists at Purdue University have discovered in rat experiments that heavy use of no-calorie sweeteners can actually make it harder to shed extra pounds. The thinking is that the sweeteners make it more difficult to control food intake and body weight.I think diet-based or low/zero calorie foods psychologically, or maybe physiologically as the study suggests, give the consumer the belief that they can then increase their calorie intake either during or immediately after the meal. So, for instance, if I go to a restaurant and I order a diet pop, I subconciously convince myself that I have now made more room for dinner. It's the old joke when you go to the fast food place, you order the double cheese and bacon burger plus the extra large fries, but then add a Diet Coke because you're on a diet.
Secondly, whenever I had a diet pop on its own, I got hungry almost immediately afterwards. I attributed this to the fact that my body knew I was consuming something, but it had no calories in it. It then ramped up wanting more calories, so I would grab a snack - usually starchy (like bread) or highish fat (peanut butter or cheese). That's bad, so I try not to drink diet pop all alone.
I think consuming the chemicals in these products needs to be subject to the same "portion control" that you would give to food with calorie contents. Someone needs to figure out the ratio of consumption of aspartame or saccharin versus the slow down in calorie burn.