Answer
Marissa's weight loss program required her to take less than her RDA in calories. If insufficient calories are taken for daily activity and maintenance , this forces the body to use stored carbohydrates and then stored lipids for needed energy. The nurse expected that after a while on her reduced calories diet, Marissa's body would be forced to metabolize some of her stored fat ; this would cause her to lose weight-- which was the object of the whole dietary modification treatment in the first place.
The nurse knew that ketone bodies in the urine is an inerrant sign of lipolysis and utilization of stored fats as an energy source. She was therefore surprised when repeated urinalyses did not pick any trace of ketone bodies in Marissa's urine. The fact that Marissa was not losing any weight confirmed the nurse in her conviction that Marissa was not following her dietary prescription, but was sneakily eating forbidden food items. That was when the nurse confronted the patient with the charge of cheating .
Work Step by Step
Could the nurse be wrong? Could Marissa have a hereditary fat metabolism abnormality? Maybe not. Apparently she is healthy, only a little overweight.
