While Tums are not technically “food”, the ingredients are still probably effecting your fasts. If you’re not seeing results and you’re having heartburn regularly, examine what you are eating in your eating window that could be causing the heartburn.
Everyone is different and can be sensitive to different things, but common heartburn causing foods can include: spicy food, citrus, tomato, chocolate, fried food, carbonation, etc. Do some googling and see if anything you are eating is a common cause and try eliminating it for a few days, see how you feel. Trial and error.
As an example for me personally, my stomach does not enjoy: bananas, coffee, tomato sauce, pizza, cake, pop, raw broccoli, fatty meats and probably more I’m not thinking of. But other people are fine eating those. But for me, these foods cause my stomach to be upset along with heartburn/indigestion. So I personally avoid those or only have occasionally.
As a relief other than Tums, try a “shot” of whole milk (or if you’re like me, lactaid milk if sensitive to dairy) before closing your window. I don’t do a whole glass, just a “shot” of it does the trick. For some reason the milk seems to neutralize the acidity in my stomach and works better for me than Tums.
Hope you find some relief and start seeing results!
Instead of tums take a tablespoon of apple cider vinegar (with the mother) in some water and drink it down. It sounds odd but it will stop the heartburn and the acetic acid will help with your fasting and blood sugar.