The jury's still out on exactly how bad artificial sweeteners are for your overall health. Ignoring any of these adverse effects and focusing solely on weight loss, you would think that a zero- or low-calorie soda would at least have little to no effect on your waistline.
Not so. But how on Earth can someone put on weight when no calories are ingested? The best guess is that artificial sweeteners influence people's appetites, making them more prone to eat unhealthy foods afterwards.
And if you think going to the gym reduces this effect, guess again. Diet drinks apparently warp your appetite regardless of how much you exercise.