It should be self evident that diet pop is bad. Read the label, and  you should be able to recognize about as many ingredients as you could in antifreeze.
Drink water, half water half juice, milk if you can tolerate it but stay away from chemicals. Even though there is no DEFINITIVE PROOF, look at the people drinking diet pop and ask yourself if they should be your role model. Keep it simple, keep it natural and if it has more than one ingredient, leave it alone.
http://www.marksdailyapple.com/diet-soda-healthy/#axzz3DP0ip1xw
http://healthyliving.msn.com/health-wellness/7-side-effects-of-drinking-diet-soda