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.
How many calories a day do you need to burn to lose weight? Calorie Secrets states that 1 pound of fat is equal to 3,500 calories. Therefore, in order to lose 1 pound of body fat you must burn 3,500 more calories than what you consume.