Yea I definitely don't consider the SAD diet meat based since they insist 45-65% daily food should come from carbs. According to the USDA I should be eating 300-400grams of carbs per day which is just insane to me. Based on my fam history it guarantee I will be a diabetic. On any day I eat maybe 0 to 30g of carbs from whole foods. The liver is always producing endogenous glucose there is no need for dietary carbohydrates. The USDA's guidelines are an absolute disgrace.
My common sources of carbs are potatoes (microwaved, then chilled in the fridge, consumed cold), stone fruits, citrus, apples, berries, avocado, peanut butter, peppers, tomatoes, yogurt, fermented vegetables.
I dont get cramps but I do supplement magnesium glycinate or taurate daily you may want to look into that if you havent.
Ive fasted for multiple days and done cardio each day w/ no cramps, just sharing my experience.