People don't realize how unhealthy our "food" is in America.
We've known for decades, hell "Eat to live, don't live to eat" was a mantra for health gurus like Jack LaLanne before I was even born, but we still push a "pro-Big-agriculture" food narrative.
He used to say "if it's made by man, don't eat it"
Our food is the cause of so many of our diseases, hyper-tension, diabetes, heart disease, the list goes on and on.
People think fasting is a "fad diet" but there really is well documented and pretty well accepted health benefits to fasting. This is the first I have heard of fasting helping with COVID long haul, but based on the studies I've read, I'm not surprised or doubtful and glad to hear of your recovery.