Potassium, sodium, magnesium.
Break your fast with a micro meal. Like…100g of turkey or chicken breast. No spice (at risk gut lining)…no carbs (much more critical after a few days….can actually be dangerous)…avoid leafy greens for first food or 2 (gut may not break it down well…pooping would suck if that happened).
I reccomend a couple days, then upping one day ar a tune from there.
More than 2 days…have an emergency fast breaking meal that us low carb and lean ready. If you suddenly don’t feel great…throwing carbs at it isn’t great.
Really stay on top of electrolytes…most important thing