Hi Saturn:

Dr. Schwarzbein doesn't allow artificial sweeteners of any kind on her program b/c they are toxic chemicals which damage the cells of your body, aging you faster.

Anything that's unnatural to your body will create side effects. You might find these sites of interest:
Sucralose Toxicity Information http://www.mercola.com/2000/dec/3/sucralose_dangers.htm

HTH,
Wanda