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Macronutrients are the nutrients the body needs in large amounts. The three macronutrients are carbohydrates, proteins and fats. For Edexcel GCSE PE, you must know the function of each macronutrient, the foods that provide it, the recommended proportions in a balanced diet, and how each relates to sporting performance.
"Macro" means large — macronutrients are needed in large quantities because they provide the body with energy and the building blocks for growth and repair.
| Macronutrient | Primary Function | Energy per Gram |
|---|---|---|
| Carbohydrates | Main energy source | 4 kcal |
| Proteins | Growth and repair of muscle tissue | 4 kcal |
| Fats | Energy reserve, insulation, protection of organs | 9 kcal |
Carbohydrates are the body's primary and preferred source of energy, particularly during exercise.
| Type | Description | Examples | Speed of Energy Release |
|---|---|---|---|
| Simple (sugars) | Small molecules; digested and absorbed quickly | Fruit, sweets, sugar, honey, energy gels | Fast — quick burst of energy |
| Complex (starches) | Large molecules; digested and absorbed slowly | Pasta, rice, bread, potatoes, oats, cereals | Slow — sustained energy release |
graph TD
A["Carbohydrates Eaten"] --> B["Broken Down to Glucose"]
B --> C["Used Immediately<br/>for Energy"]
B --> D["Stored as Glycogen<br/>(Muscles & Liver)"]
D --> E["Converted Back to Glucose<br/>During Exercise"]
D --> F["If Stores Full:<br/>Stored as Fat"]
style A fill:#f39c12,color:#fff
style C fill:#27ae60,color:#fff
style D fill:#1565c0,color:#fff
Carbohydrates should make up approximately 55–60% of total energy intake.
Exam Tip: When discussing carbohydrates, always distinguish between simple and complex. The exam frequently asks which type is best before, during or after exercise.
Proteins are essential for growth and repair of body tissues, particularly muscle tissue.
| Function | Detail |
|---|---|
| Growth and repair | Builds and repairs muscle tissue, especially after exercise |
| Enzyme production | Proteins form enzymes that control chemical reactions in the body |
| Hormone production | Some hormones (e.g. insulin) are proteins |
| Immune function | Antibodies that fight infection are made from protein |
| Secondary energy source | The body can use protein for energy if carbohydrate stores are depleted (not ideal) |
| Animal Sources | Plant Sources |
|---|---|
| Chicken, turkey, beef, pork | Beans, lentils, chickpeas |
| Fish (salmon, tuna, cod) | Tofu, tempeh |
| Eggs | Nuts and seeds |
| Milk, cheese, yoghurt | Quinoa |
Proteins should make up approximately 15–20% of total energy intake.
Athletes involved in strength and power sports (weightlifting, sprinting, rugby) often consume more protein to support muscle growth and repair.
Fats provide energy, particularly during low-intensity, long-duration exercise. They also serve important non-energy functions.
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