What can prolonged fasting lead to in terms of urine composition?

Prolonged fasting significantly impacts the body’s metabolism, leading to a state known as ketosis. During fasting, the body exhausts its glycogen stores and starts to metabolize fat for energy. As a result of fatty acid metabolism, ketone bodies are produced. These ketones—acetoacetate, beta-hydroxybutyrate, and acetone—then enter the bloodstream and can be excreted in the urine.

The presence of ketones in urine is indicative of this metabolic shift, signaling that the body is using fat as its primary energy source instead of carbohydrates. This is common during periods of prolonged fasting or in conditions like uncontrolled diabetes, where insulin deficiency also leads to ketosis.

In contrast, the other options represent changes in urine composition that are not typically associated with fasting. Increased bilirubin levels may indicate liver dysfunction or biliary obstruction, while higher urine pH is often related to dietary factors or renal tubular functions rather than fasting. Increased uric acid levels can occur due to various conditions, including dehydration or a diet rich in purines, but this is not a direct consequence of prolonged fasting compared to the production of ketones. Thus, the presence of ketones stands out as the correct choice in this scenario, reflecting