Hey Slapshot! I just went online and found the Acceptable Foods list for Induction and the below does state that Diet Soda is ok and to check the carb count.
Beverages- Clear broth/ bouillon (make sure it has no sugars added)
- Club soda
- Cream, heavy or light.
- Decaffeinated or regular coffee and tea*
- Diet soda (be sure to note the carb count)
- Flavored seltzer (must say no calories)
- Herb tea (without added barley or fruit sugar added)
- Water – at least eight 8-ounce glasses per day including...
- Filtered water
- Mineral water
- Spring water
- Tap water