Which of the following nutrients has the highest source of calories?

Appeared in: SGPGI Nursing Officer-2022

Explanation

Fat is the most energy-dense macronutrient, providing approximately 9 kilocalories (kcal) of energy for every gram consumed.
This is more than double the energy provided by carbohydrates and proteins, which each supply about 4 kcal per gram.
Due to this high energy density, fats are the body's most efficient way to store energy for later use.

Option B: Protein provides 4 kcal per gram, which is less than half the energy provided by fat.
Option C: Carbohydrates provide 4 kcal per gram, significantly less than the 9 kcal per gram from fat.
Option D: Vitamins are micronutrients that are essential for metabolism but do not provide any calories or energy.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Caloric content of macronutrients as background academic context rather than a clinical decision trigger.
Understanding the caloric density of macronutrients is fundamental for nutritional assessment, patient education, and diet planning for conditions like obesity, diabetes, and malnutrition.
Nurses use this knowledge to counsel patients on weight management, explaining how high-fat foods contribute more significantly to total calorie intake than equal amounts of carbohydrates or proteins.
What if? If a patient requires a high-calorie diet for weight gain (e.g., due to cancer or malabsorption), the nurse would recommend incorporating healthy, energy-dense fats to increase caloric intake without excessively increasing food volume.

How to Approach the Question

This is a factual recall question from the subject of Nutrition.
Identify the key term in the question: 'highest source of calories'.
Recall the standard caloric values for the main macronutrients and micronutrients listed in the options.
Compare the values: Fat (9 kcal/g), Protein (4 kcal/g), Carbohydrates (~4 kcal/g), and Vitamins (0 kcal/g).
Based on this comparison, fat provides the most calories per gram. Select the option that reflects this fact.

Concept Tested & Keywords

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E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 180-182

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

Practise the full SGPGI Nursing Officer-2022

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