A nutrition label gives the nutritional values of a food for a specific quantity. To work out the calories in your portion, start with the right column and account for what you actually consumed. Here is a simple way to go from the label to your food diary.
1. Identify the reference quantity
Start by reading the table heading: do the values refer to 100 g, 100 ml or one portion? Also check whether the manufacturer describes the product as sold or after preparation. A dry powder and a prepared drink do not have the same weight.
The portion stated on the packaging is the table's reference. It may differ from the amount you consume. For a bar, sachet or tub, also check how many portions the package contains.
2. Calculate the calories in your portion
Calories per portion = calories per 100 g × quantity consumed in grams ÷ 100.
Let's take a completely fictional example : a food lists 380 kcal per 100 g. You consume 30 g. The calculation is 380 × 30 ÷ 100 = 114 kcal. With 45 g of the same food, the result would be 171 kcal. These numbers illustrate the method; they do not describe any product sold on the site.
If the table already gives values for a 30 g portion and you have two portions, multiply those values by two. For a drink with values per 100 ml, use the volume consumed in millilitres. Keep the same reference unit.
3. Use the same calculation for macronutrients
The same rule applies to protein, carbohydrates and fat. In our fictional example, a 30 g portion is 0.3 times the values per 100 g.
| Value | Per 100 g | Per 30 g |
|---|---|---|
| Energy | 380 kcal | 114 kcal |
| Protein | 12 g | 3,6 g |
| Carbohydrate | 65 g | 19.5 g |
| Fats | 8 g | 2.4 g |
For calories, use the energy line on the label. You do not need to reconstruct its value from the macronutrients to record your portion.
4. Include anything you add
Adding water to a powder changes its weight and volume, but adds no calories. Milk, plant-based drinks, oil or sauce, however, contribute their own nutritional values. Check their labels and add them separately, unless the product's table already includes them in a specifically described preparation.
Another fictional example: to our 114 kcal, you add 150 ml of a drink with 60 kcal per 100 ml. That adds 90 kcal, bringing the total to 204 kcal. The figure depends on the drink actually used.
5. Avoid quantity errors
Do not combine the nutritional values of a dry food with its weight after cooking. Use an entry that matches the state of the food you are measuring. Also check whether a scoop actually holds the stated quantity: its volume does not automatically give its weight in grams.
A quick check is often enough: the right product, unit and quantity, with added ingredients accounted for. This calculation describes a portion; it does not set your daily calorie needs.
Keep your meals in your Healthy Club diary
You can then search for the food in your diary and enter the quantity consumed. Check the product and its values before saving it, then add any ingredients used separately. Your meals stay together in your personal space. Available features depend on your plan.
Open my Healthy Club food diary
To compare labels in our catalogue, browse our whey protein and protein snacks. Availability is shown on each product page.
For more on reading portion information on a label: the FDA guide to understanding nutrition labels.
