This isn’t solid medical advice but I just listen to my body. Sometimes I straight up lose my appetite for a day or two (usually after eating a lot for a few days), so I fast. Other times I try to force a fast where I keep getting hungry. After practicing fasting for almost a few years now I notice there’s cravings, and sometimes genuine hunger where my body is telling me to refeed.
2 days may be a bit short, but 4-5 days probably will be fine. That puts you at roughly once a week.
Re solid foods: only refeed keto friendly foods and you won’t put on weight and youll get into fast mode super quick when you start fasting again. Steak, eggs, salmon, avacado, these foods will nourish and keep the progress going