The energy liberated from each gram of carbohydrates is?

Appeared in: DSSSB - 29 August 2019 (Shift-1)

Explanation

The physiological fuel value of carbohydrates is approximately 4.1 kilocalories (kcal) per gram.
This value represents the metabolizable energy available to the body after digestion and absorption.
Carbohydrates are the body's preferred and primary source of fuel for most functions, especially for the brain and during high-intensity exercise.
The Atwater system is the standard method for determining the caloric content of foods.

Option A: 3 calories per gram is not the standard energy value for any of the major macronutrients.
Option B: 2 calories per gram is not a recognized physiological fuel value for carbohydrates, proteins, or fats.
Option D: 3 calories (or 9 kcal/g) is the energy value for fats (lipids), not carbohydrates.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Energy value of macronutrients (carbohydrates) as background academic context rather than a clinical decision trigger.
Nurses use knowledge of macronutrient energy values for nutritional assessments and to plan diets for patients.
This is critical in managing conditions like diabetes, obesity, and malnutrition, where precise calorie and macronutrient counting is necessary.
Patient education often involves explaining these basic concepts to help individuals make informed dietary choices for weight management or disease control.

How to Approach the Question

This is a factual recall question common in nutrition.
Identify the core components of the question: 'energy' and 'carbohydrates'.
Recall the standard physiological fuel values (Atwater factors) for the three main macronutrients.
Carbohydrates and proteins both provide approximately 4 kcal/g.
Fats provide approximately 9 kcal/g.
Compare these known values to the options provided and select the one that matches the value for carbohydrates (4.1 kcal/g).

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 2 p. 502-504

E6 Harper's Illustrated Biochemistry2023 (pp 26-793 of 813) p. 128-130

E6 textbook of Applied Biochemistry and Nutrition & DieteticsHarbans Lal (pp 26-464 of 479) p. 258-260

Practise the full DSSSB - 29 August 2019 (Shift-1)

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