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.
Keep in mind that fat contains 9 calories per gram, while carbohydrates and protein only provide 4 calories per gram. When choosing a low-fat diet for weight loss, your fat intake should not go below 20 percent of your total daily calorie intake. The National Heart, Lung and Blood Institute respectively suggests women and men to eat 1,000 to 1,600 calories per day and 1,200 to 1,600 calories per day for successful and safe weight loss.