Q.In a balanced diet for a moderately active adult, carbohydrates should supply approximately what share of the total energy intake?
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Start your 14-day free trial to unlock the full solution →Carbohydrates supply the largest share of energy in a balanced diet — about 55–60% (fats 25–30%, proteins 10–15%). Answer: (d) 55–60%.
Concept understanding — the macronutrient energy split
A balanced diet is one that supplies all the nutrients in the right proportion and quantity for a person's age, sex and activity level. For the three energy-yielding (macro) nutrients, "the right proportion" is expressed as a share of the total daily energy intake:
| Macronutrient | Share of total energy | Energy value | Chief role |
|---|---|---|---|
| Carbohydrates | ≈ 55–60% | 4 kcal per gram | Primary fuel — blood glucose and muscle/liver glycogen |
| Fats | ≈ 25–30% | 9 kcal per gram | Concentrated energy store; insulation; carries vitamins A, D, E, K |
| Proteins | ≈ 10–15% | 4 kcal per gram | Growth and repair of tissue; enzymes and hormones |
(Water, minerals, vitamins and roughage are the non-energy-yielding nutrients — essential, but contributing no calories.)
Why carbohydrates take the biggest share
- They are the cheapest fuel to burn. Carbohydrate needs less oxygen per unit of energy released than fat does, so it is the fuel of choice for high-intensity work.
- The brain and red blood cells need glucose. They cannot ordinarily run on fat.
- Glycogen is the limiting store. Muscle and liver glycogen is small and runs out; when it does, an athlete "hits the wall". A high-carbohydrate intake keeps it topped up — which is why endurance athletes carbohydrate-load before an event.
- Protein-sparing. If carbohydrate is short, the body breaks down protein for energy — robbing the tissue-repair budget. Adequate carbohydrate "spares" protein for its real job.
A moderately active adult's carbohydrate should come mainly from complex carbohydrates — whole grains, millets, pulses, fruits and vegetables — which release glucose slowly and bring fibre with them, rather than from simple sugars. …
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