This guide will help you answer 1.4 Use nutritional information from food labels to calculate the energy provided by fat, protein and carbohydrate in each food.
What is the Purpose of Food Labels?
Food labels play a central role in nutrition and health. They let you see what goes into the food you eat every day. You can learn how much fat, protein, and carbohydrate is present in each product. With this information, you can work out the amount of energy you get from these nutrients.
Many people use food labels to keep a healthy weight, manage certain health conditions, or reach fitness goals. Menu labels in shops and restaurants use similar rules. Being able to read food labels helps you make better decisions about your food.
Labels must meet rules set by law. In the UK, they follow guidelines from the Food Standards Agency and other bodies. This includes showing the energy content in both kilojoules (kJ) and kilocalories (kcal).
Macronutrients and Energy
Your body gets energy from three main macronutrients:
- Fat
- Protein
- Carbohydrate
Each one provides a set amount of energy per gram. This is measured in kilocalories and kilojoules.
Let’s break it down:
- Fat gives 9 kilocalories (kcal) per gram.
- Protein gives 4 kilocalories (kcal) per gram.
- Carbohydrate gives 4 kilocalories (kcal) per gram.
Kilocalories, often called ‘calories’, show the amount of energy in food.
What Does a Food Label Show?
Most food labels show:
- Energy in kJ and kcal per 100g and per serving
- Amount of fat (total and saturated) in grams
- Amount of carbohydrate (total and sugars) in grams
- Amount of protein in grams
- Amount of salt and fibre
Here is a sample label for a breakfast cereal (per 100g):
- Energy: 370 kcal / 1548 kJ
- Fat: 2g
- Protein: 9g
- Carbohydrate: 76g
- Sugar: 10g
- Fibre: 7g
Some labels might show info ‘per portion’ or ‘per slice’. Always check the serving size to do accurate calculations.
Finding the Nutritional Values
Look for the nutritional information box. This usually appears on the side or back of the packet. It may look like this:
| Nutrient | per 100g | per serving |
|---|---|---|
| Energy | 370 kcal | 111 kcal |
| Fat | 2g | 0.6g |
| Protein | 9g | 2.7g |
| Carbohydrate | 76g | 22.8g |
Note: Always double check if the values are for 100g or per serving.
How to Calculate Energy from Fat, Protein, and Carbohydrate
You can calculate the total energy provided by fat, protein, and carbohydrates using simple maths. This is important if you want to check how much of your energy is coming from each nutrient.
Step 1: Find the Amount per Nutrient
First, find how many grams of fat, protein, and carbohydrate are in the food. Use either the ‘per 100g’ or ‘per serving’ column.
Step 2: Multiply by the Energy Value
Multiply the grams of each nutrient by the appropriate figure:
- Fat: 9 kcal per gram
- Protein: 4 kcal per gram
- Carbohydrate: 4 kcal per gram
Step 3: Add the Totals
Add up the energy from each nutrient to get the overall energy count that comes from those macronutrients.
Example Calculation
Let’s use the breakfast cereal example (per 100g):
- Fat: 2g
- Protein: 9g
- Carbohydrate: 76g
Calculation:
- Energy from fat: 2g x 9 = 18 kcal
- Energy from protein: 9g x 4 = 36 kcal
- Energy from carbohydrate: 76g x 4 = 304 kcal
Now, add these up:
- 18 kcal (fat)
- 36 kcal (protein)
- 304 kcal (carbohydrate)
- Total = 358 kcal
On the label, the energy per 100g is 370 kcal. There is a small difference. This is normal; labels sometimes include energy from fibre, alcohol, or tiny differences in rounding. Always focus on the main figures.
Energy Provided by Fat, Protein, and Carbohydrate
Each macronutrient has a specific role:
- Fat is a high-energy source. Your body stores extra energy as fat.
- Protein builds and repairs tissues. Your body can use protein for energy if it must.
- Carbohydrate is your body’s main energy source, especially for the brain and muscles.
Knowing how much of your energy comes from each nutrient helps you keep a balanced diet.
Why Calculate Energy from Each Nutrient?
Calculating the energy from separate nutrients helps you:
- Spot foods high in energy from fat, which may affect your heart health
- Check if you’re getting enough protein for muscle repair and immune function
- Limit excess sugar if you are watching your blood sugar
People with diabetes, athletes, or those aiming to lose weight find this useful.
Working Out Percentages
You can work out what percentage of the energy comes from each macronutrient.
Here’s how:
- Work out the energy provided by each nutrient.
- Add them together for the total.
- Divide the figure for each by the total and multiply by 100.
Example
Using the above numbers:
- Fat: 18 kcal
- Protein: 36 kcal
- Carbohydrate: 304 kcal
- Total: 358 kcal
Percentage from each:
- Fat: (18 / 358) x 100 = 5%
- Protein: (36 / 358) x 100 = 10%
- Carbohydrate: (304 / 358) x 100 = 85%
So, the cereals get most of their energy from carbohydrates.
Tips for Using Food Labels
Food packaging can vary, but here are ways to make the most of the information:
- Double check if figures are per 100g or per serving
- Look at both the total and the breakdown of fat, protein, sugars, and starches
- Compare foods using the ‘per 100g’ figures—this is standard for comparing similar foods
- Watch out for small serving sizes which might make a food look ‘lighter’ than it really is
- Round numbers are normal; very small differences are expected
Always aim for foods that fit your needs.
How to Use This Skill in Daily Life
Here’s a quick practical example using a snack bar label:
Label (per 35g bar):
- Fat: 6g
- Protein: 3g
- Carbohydrate: 20g
Energy from each:
- Fat: 6g x 9 = 54 kcal
- Protein: 3g x 4 = 12 kcal
- Carbohydrate: 20g x 4 = 80 kcal
Total from macros: 54 + 12 + 80 = 146 kcal
If the label says the bar contains 150 kcal per serving, this matches closely.
This method shows you which foods are high in fat (e.g., crisps, cheese), protein (e.g., fish, eggs), or carbohydrate (e.g., rice, bread). It helps you choose snacks and meals that suit your health and dietary goals.
Common Terms on Labels
Some labels use technical words. Here’s what they mean:
- kcal (kilocalories): Used to describe energy. One kcal is the amount of energy to raise 1 kg of water by 1°C.
- kJ (kilojoules): Another measure of energy. 1 kcal = 4.184 kJ.
- Saturates: These are saturated fats. High levels can affect cholesterol.
- Sugars: Quick release carbohydrates. Too much sugar can affect dental health and blood sugar.
Key Points to Remember
- Always check the amount (per 100g or per serving)
- Fat, protein and carbohydrate contain different amounts of energy per gram
- Use the multiplication sums to work out energy from each nutrient
- Use this information to choose foods that match your goals
Handling Special Cases
Some food items may contain extra types of fat (like polyunsaturated or trans fats), or different types of carbohydrates (fibres, sugars). Not all types contribute the same amount of energy.
For instance, fibre often provides less energy. Labels might not include these specifics in calorie counts. If in doubt, use the main figures on the label.
Practice Examples
Try calculating the energy for these two foods:
Yoghurt (per 120g pot):
- Fat: 1g
- Protein: 5g
- Carbohydrate: 15g Energy from fat: 1 x 9 = 9 kcal
Energy from protein: 5 x 4 = 20 kcal
Energy from carbohydrate: 15 x 4 = 60 kcal
Total = 89 kcal
Cheddar cheese (per 30g):
- Fat: 10g
- Protein: 7g
- Carbohydrate: 0.2g Energy from fat: 10 x 9 = 90 kcal
Energy from protein: 7 x 4 = 28 kcal
Energy from carbohydrate: 0.2 x 4 = 0.8 kcal
Total = 118.8 kcal
Now you can quickly spot that yoghurt is mostly carbohydrate, while cheese is mostly fat and protein.
Avoiding Misleading Labels
Be cautious with claims like ‘light’, ‘low fat’, or ‘sugar-free’. These do not always mean low in energy. Some products replace fat with extra sugar or vice versa. Keep your eye on the full nutritional table.
Food Labelling in the UK
Current UK laws require most pre-packed foods to show this information clearly. The labels must be easy to find, read, and understand.
Manufacturers sometimes show Guideline Daily Amounts (GDAs) to make comparison easier. These are recommendations for how much of each nutrient a typical adult needs each day.
Final Thoughts
Using nutritional information from food labels is a valuable skill. It puts you in charge of the food you eat. Once you can calculate the energy from fat, protein, and carbohydrate, choosing balanced meals becomes much simpler.
This tool gives you control. You can spot foods that offer more of what you want—whether you are aiming to build muscle, manage your weight, or care for your heart. Each label serves as a small guide. With practice, using food labels will feel quick and natural.
Food choices affect health, mood, and energy levels. By reading and working out the nutritional content, you make informed decisions. These small daily actions add up over time.
If you ever feel unsure, keep a calculator with you or use the one on your phone. Remember the energy values for each macronutrient:
- Fat: 9 kcal per gram
- Protein: 4 kcal per gram
- Carbohydrate: 4 kcal per gram
Now, go and practice with real food labels at home or in the shop. This skill will serve you for life and support your work in nutrition and health.
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