I use fasting and eat generally a carnivore diet but do slip out of ketosis when I have red wine or eat a rare slice of my homemadr sourdough.
I am not jabbed, but I now have the worst cold/flu for 10 years. I am coughing and spluttering, and drinking honey with boiled water. I have gone hoarse.
I live in subtropical Queensland. We are nearing the end of a very, very cold winter.
I dont know if being in ketosis helps with immunity. I do think fasting helps.
When my throat clears up I may do 3-5 day water fast.