Curriculum
Science — Second Preparatory
Unit 1: Matter and Energy
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Unit 2: Matter and Chemical Reactions
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Unit 3: Energy Flow in Photosynthesis and Respiration
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Unit 4: Geological Processes
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Text lesson
Chemistry of Nutrition
Chemistry of Nutrition
The energy supplied by food
The energy supplied by food
- Food energy is measured in kilocalories (kcal). Approximately
- one gram of each nutrient gives:
| Nutrient | Energy per gram |
|---|---|
| Carbohydrates | 4 kcal |
| Proteins | 4 kcal |
| Fats | 9 kcal |
Key points
Worked exampleA meal contains 50 g of carbohydrates, 20 g of fats and 30 g of proteins. Calculate its total energy.
Solutioncarbohydrates: 50 × 4 = 200 kcal
fats20 × 9 = 180 kcal
proteins30 × 4 = 120 kcal
Total energy = 200 + 180 + 120 = 500 kcal
- Fats give the most energy per gram
- so they should be eaten in moderate amounts.
Chemistry of Nutrition · 4 / 7