Eat until you’re full. Eat when you’re hungry. Same with water – drink when you’re thirsty. However, if your body is all out of sorts it’s not quite that simple.
If you’re excessively thirsty you should try salting your water. Don’t drink unsalted water. You could be thirsty because your body is asking for electrolytes and drinking unsalted water can dehydrate you if you drink too much. Add salt to your water if you’re excessively thirsty. Also, remember that if you’re anxious you can get quite thirsty – monitor this because drinking too much water will dehydrate you if you don’t add salt. Think saline solution in hospitals – they use that in your blood, not water. You need the salt if you’re excessively thirsty.
For food, you should be eating approximately how many calories your body height requires. I ate a lot more at the beginning of the diet. A lot of people do. People suffering from tissue damage may need more calories to heal. Try not to worry about the amount – I’d worry about under-eating more than overeating.
However, if you find you’re eating 5 pounds of meat a day and you’re 5’8 then you can’t intuitively eat and you need to eat based on calories. Some people are so out of whack with their hunger cues that when they stop eating carbs they don’t understand what full feels like without bloating (hi, me). That can confuse people. So go based on calories approximately.
I’m 5’6 and I eat about 1.5 lbs of meat a day if averaged over a week. Men who are 6’ should eat about 2.5 lbs. If that’s off by ½ lb that’s okay. Generally speaking, just eat how much you feel like you should.