What is the calorific value of carbohydrates?

Appeared in: BTSC Staff Nurse 30July-2025

Explanation

Carbohydrates are a primary source of energy for the body.
The standard physiological energy value for carbohydrates is 4 kilocalories per gram (kcal/g).
This value is used in nutritional science to calculate the energy content of foods and to plan diets.
The body metabolizes carbohydrates (as glucose) to provide fuel for cellular activities, especially for the brain and muscles.

Option B: 2 kilocalories per gram is not the standard calorific value for any major macronutrient and represents a significant underestimation of the energy provided by carbohydrates.
Option C: 7 kilocalories per gram is the calorific value of alcohol, not carbohydrates. While alcohol provides energy, it is not considered a nutrient because it does not support growth or tissue repair.
Option D: 9 kilocalories per gram is the calorific value for fats (lipids). Fats are the most energy-dense macronutrient, providing more than double the energy per gram compared to carbohydrates.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calorific Value of Macronutrients as background academic context rather than a clinical decision trigger.
Nurses use knowledge of calorific values to educate patients on weight management, explaining how different foods contribute to total energy intake.
This concept is critical in managing diabetic patients, where carbohydrate counting (based on 4 kcal/g) is a key strategy for maintaining blood glucose control.
For patients with malnutrition or those requiring nutritional support (e.g., via enteral feeding), nurses must accurately calculate caloric needs and intake, making knowledge of these values essential for formulating feeding plans.

How to Approach the Question

Identify the core question: It asks for a specific, factual nutritional value.
Recognize this as a factual recall question. The answer is a standard value in nutrition science.
Recall the energy values for the main macronutrients: carbohydrates, proteins, and fats.
Carbohydrates provide 4 kcal/g.
Proteins also provide 4 kcal/g.
Fats provide 9 kcal/g.

Concept Tested & Keywords

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E6 textbook of Applied Biochemistry and Nutrition & DieteticsHarbans Lal (pp 26-464 of 479) p. 252-254

E6 Nutrition Monika Sharma 3e p. 49-51

Practise the full BTSC Staff Nurse 30July-2025

Attempt every question from this paper in a timed mock, then review the full solution for each one.