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This lesson covers the recommended proportions of energy from macronutrients, the use of food tables and nutritional analysis, as required by AQA GCSE Food Preparation and Nutrition specification 8585, section 3.2.3. You must understand how total daily energy should be distributed among carbohydrates, proteins, and fats, and be able to use this knowledge to evaluate diets and plan meals.
Dietary Reference Values (DRVs) are a set of guidelines published by the UK government that recommend how much of each nutrient different groups of people need. They include:
| Term | Meaning |
|---|---|
| Reference Intake (RI) | The amount of energy or nutrients that meets the needs of most healthy adults. Used on food labels. |
| Reference Nutrient Intake (RNI) | The amount of a nutrient sufficient for 97.5% of a population group. If you meet the RNI, your diet is almost certainly adequate for that nutrient. |
| Estimated Average Requirement (EAR) | The average amount of energy or a nutrient needed by a group of people. 50% of the group will need more, and 50% will need less. |
| Lower Reference Nutrient Intake (LRNI) | The amount sufficient for only 2.5% of the population. If intake falls below LRNI, the person is likely to be deficient. |
Exam Tip: The key term for the exam is Reference Intake (RI), which is what you see on food packaging. The RI for energy is 2,000 kcal for an average adult. Remember that RIs are based on an average adult — individual needs vary.
The UK government recommends that the total energy in a person's diet should come from macronutrients in the following proportions:
| Macronutrient | Recommended % of Total Energy | Notes |
|---|---|---|
| Carbohydrate | 50% | Including starch and intrinsic sugars (naturally occurring in whole fruit, vegetables, milk). Maximum 5% from free sugars (added sugars, honey, syrups, fruit juice). |
| Protein | 15% | From a mixture of animal and plant sources. |
| Total fat | 35% or less | Of which no more than 11% from saturated fat. The remainder should come from unsaturated fats (mono- and polyunsaturated). |
Free sugars are any sugars added to food or drinks, plus sugars naturally present in honey, syrups, fruit juices, and smoothies. They do not include sugars naturally found in whole fruit, vegetables, or milk (these are called intrinsic sugars).
The recommendation to limit free sugars to 5% of total energy (about 30 g or 7 sugar cubes per day for adults) is based on evidence linking excessive sugar consumption to:
Exam Tip: When analysing a diet, distinguish between free sugars (added/processed) and intrinsic sugars (naturally in whole food). Eating an apple (intrinsic sugar + fibre) is very different from drinking apple juice (free sugar, no fibre).
graph TD
A["Total Daily Energy"] --> B["Carbohydrate 50%"]
A --> C["Protein 15%"]
A --> D["Total Fat ≤ 35%"]
B --> B1["Starch & intrinsic sugars<br/>45%"]
B --> B2["Free sugars<br/>max 5%"]
D --> D1["Saturated fat<br/>max 11%"]
D --> D2["Unsaturated fat<br/>(remainder)"]
style A fill:#2c3e50,color:#fff
style B fill:#f39c12,color:#fff
style C fill:#8e44ad,color:#fff
style D fill:#e74c3c,color:#fff
style B2 fill:#c0392b,color:#fff
style D1 fill:#c0392b,color:#fff
If an adult consumes 2,000 kcal per day, the recommended breakdown is:
| Macronutrient | % of Energy | Energy (kcal) | Weight (g) |
|---|---|---|---|
| Carbohydrate | 50% | 1,000 kcal | 1,000 ÷ 3.75 = 267 g |
| Protein | 15% | 300 kcal | 300 ÷ 4 = 75 g |
| Fat | 35% | 700 kcal | 700 ÷ 9 = 78 g |
| of which saturated fat | 11% | 220 kcal | 220 ÷ 9 = 24 g |
| of which free sugars | 5% | 100 kcal | 100 ÷ 3.75 = 27 g |
Exam Tip: You may be asked to calculate the grams of each macronutrient from a given energy intake. The method is: (total kcal × percentage) ÷ energy per gram. Always show your working clearly.
Food composition tables (e.g. McCance and Widdowson's The Composition of Foods) list the nutrient content of hundreds of foods per 100 g. They are used to:
In the exam, you may be given a simplified food table and asked to calculate the nutrient content of a meal or evaluate whether it meets the recommended proportions.
All pre-packaged foods in the UK must display a nutrition information panel showing the following per 100 g (or 100 ml) and per portion:
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