You could get Natural Vitality Calm Magnesium Powder. I've used it in fasting with no issues, because I like using it as a lemonade with salt/lite salt, squirt of lemonade mio. I can sip on that for a while when I feel like it's "meal time" and it gets me through. I use 1tsp of this (magnesium) and 1tsp lite salt (potassium/sodium) 1/4-1/2 tsp of baking soda (sodium) in about 20oz water with mio, and drink two of those a day when fasting.