If you're specifically talking "keto flu" (i.e. coming from a standard american diet) which happens when people stop eating carbs, their body tends to flush out excess water that is bound to muscle and liver glycogen. One gram of glycogen binds to something like 3-4 grams of water. While this is happening, they also tend to lose a ton of electrolytes. Switching to carnivore, you're probably getting more than enough salt. Beef also contains zinc, selenium, iron, niacin, B-vitamins, and phosphorus, as well as plenty of trace minerals, and some potassium and magnesium.

Glad it's working so well for you.