Ketosis is typically associated with elevated ketone bodies from fat breakdown for energy. In which context is ketosis most likely to occur?

• A. Regular, balanced meals
• B. Short-term high-carbohydrate diet
• C. Prolonged fasting
• D. Moderate protein intake

Answer: (C)

Ketosis happens when the body has to rely on fat for energy because glucose is scarce. In prolonged fasting, liver glycogen stores run low, insulin falls, and fats are released from adipose tissue. The liver then converts those fatty acids into ketone bodies (such as acetoacetate and beta-hydroxybutyrate) to supply energy to the brain and other tissues. As a result, ketone levels rise in the blood, defining ketosis. A regular, balanced meal pattern keeps insulin present and prevents large amounts of fat from being released for energy, so ketosis is unlikely. A short-term high-carbohydrate diet provides ample glucose, further suppressing ketone production. Moderate protein intake by itself doesn’t push ketone formation unless carbohydrate is also restricted; it mainly supports gluconeogenesis rather than ketogenesis under typical conditions. Thus, prolonged fasting is the context most likely to induce ketosis.