Definition. The urine creatinine test measures the amount of creatinine in urine. Creatinine is a breakdown product of creatine, which is an important part of muscle. Creatinine is removed from the body entirely by the kidneys. Creatinine can also be measured by a blood test.
Ketones are the byproduct of breaking fatty acids down to be burned. Okay, it's a water fast, but we can assume that after 3 days, ketosis is acheived. About 250 grams of fat is about the maximum amount of fat that will be burned daily. I say around 250-300 grams per day.
1 Limiting the amount of saturated fats you eat to less than 7 percent of your total daily calories. That means if you need about 2,000 calories a day, less than 140 calories (or 16 grams) should come from saturated fats.  Limiting the amount of trans fats to less than 1 percent of your total daily calories. That means if you need about 2,000 calories a day, less than 20 calories (or 2 grams) should come from trans fats.