A person on a long hunger strike, surviving only on water will have

The correct answer is "less urea in his urine".

To understand why a person on a prolonged hunger strike (surviving only on water) would have less urea in their urine, we need to trace through the body's metabolic response to starvation step by step.

Step 1: Understanding Where Urea Comes From
Urea is the primary nitrogenous waste product in humans. It is produced in the liver through the urea cycle (ornithine cycle), and it is excreted by the kidneys into the urine. The key point is: urea is formed from the breakdown of amino acids. Specifically, when amino acids are catabolized (broken down), their amino (-NH₂) groups are removed through a process called deamination, producing ammonia (NH₃), which is then converted into urea in the liver.

Step 2: What Happens to Protein Metabolism During Starvation?
In the early stages of starvation, the body first depletes its glycogen (sugar) stores, then mobilizes fat reserves. After prolonged starvation — as in a long hunger strike — the body's fat stores begin to run dangerously low. However, the body is remarkably conservative about breaking down its own proteins. Protein catabolism does occur during starvation but at a significantly reduced and carefully regulated rate.

In prolonged starvation, the body shifts to using ketone bodies (derived from fat breakdown) as the primary fuel, even for the brain — a process called ketosis. This spares proteins (and thus amino acids) from being broken down as much as possible, because muscle and vital organ proteins are essential for survival.

Step 3: Less Amino Acid Breakdown → Less Deamination → Less Urea
Since the body is conserving protein and breaking down fewer amino acids during prolonged starvation:

↓ Protein catabolism
⇒ ↓ Free amino acids available for deamination
⇒ ��� Ammonia (NH₃) production
⇒ ↓ Urea synthesis in the liver
⇒ ↓ Urea excreted in the urine

Therefore, the amount of urea in the urine decreases during a long hunger strike. The person produces and excretes less urea, not more.

Why the Other Options Are Incorrect:

• "Less amino acids in his urine" — Amino acids are not significantly excreted in normal urine even under healthy conditions; urea is the end product. This option conflates amino acid metabolism with excretion and is not a characteristic change of starvation.

• "More glucose in his blood" — During starvation, blood glucose levels actually decrease and are maintained at a low but stable level through gluconeogenesis. Hyperglycemia (high blood glucose) is associated with diabetes, not starvation.

• "More sodium in his urine" — During starvation, the kidneys actually conserve sodium more aggressively (through aldosterone and other hormones) to maintain blood pressure and electrolyte balance. Sodium in urine tends to decrease, not increase.

Conclusion:
A person on a long hunger strike conserves body protein to the maximum extent possible, breaking down fewer amino acids. This results in reduced deamination, reduced ammonia production, and ultimately less urea synthesized and excreted in the urine. This is the correct and expected metabolic outcome of prolonged starvation.