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What is carbohydrate counting?
Carbohydrate counting enables better control of diabetes; by helping you adjust insulin doses to match the carbohydrate content of each meal.
Insulin is needed to maintain normal blood glucose levels in response to carbohydrates eaten. When you eat carbohydrates (both starches and sugars), they are broken down into glucose and absorbed into your bloodstream where they can be used for energy.
It is important to have a good understanding of how much and what type of carbohydrate is in the foods you eat. This will help you work out how much insulin you need to give with meals and snacks.
This can be achieved by a variety of methods which we will look at in this leaflet.
Why should I do carbohydrate counting?
Carbohydrate counting allows you to get better diabetes control with insulin injections and is essential if you wish to have an insulin pump.
Research has shown that children with diabetes and their families who accurately count carbohydrates achieve better blood glucose control and lower HbA1c levels.
It will also give you greater confidence at mealtimes, as new skills replace the guess work from managing diabetes.
How do carbohydrates affect blood glucose?
When we eat food, it is broken down into its simplest form in the stomach and the intestines by the process of digestion. The smaller nutrients are then absorbed into the blood.
Carbohydrates in foods are digested and end up as glucose in the blood. There are two main types of carbohydrate - starches and sugars (naturally occurring or added), examples of which can be seen below:
|
Starches |
Sugars |
|
|
Potatoes, sweet potato, yam, plantain |
Natural |
Added |
|
Bread, chapattis and flour based products e.g. pizza base/crackers |
Fruit |
Sweets/chocolate |
|
Breakfast cereals |
Fruit juice/smoothie |
Squashes |
|
Porridge, oats |
Some vegetables |
Fizzy drinks |
|
Rice, pasta, noodles |
Milk |
Jams/marmalade |
|
Pulses e.g. baked beans |
Yoghurt |
Cakes/biscuits |
|
Couscous, quinoa, lentils |
Fromage frais |
Desserts |
Note:
Starchy (or complex) carbohydrate foods should be eaten regularly to provide the body with energy. They usually raise blood glucose levels more slowly than sugary foods. However, this depends on how much is eaten, how processed the food item is and the cooking process. This is referred to as the foods Glycaemic Index (ask your Dietitian for further information on this).
Calculating carbohydrates
There are lots of tools to help you calculate the carbohydrate in the food you eat. Nutritional labels, reference books, websites and apps often provide information in serving or portion sizes.
These handy tools are helpful, but to be accurate weighing and measuring your serving is best. If you have a different amount of the food from the suggested serving, you must calculate how much carbohydrate you have. Estimating your carbohydrate can lead to big differences, so your blood glucose control may not be as good as it could be.
Methods of carbohydrate counting
There are four ways to do carbohydrate counting. Most people will find they use a combination of these initially until they become familiar with their portion sizes and carbohydrate content of their foods:
1. Food label suggested portions
- Whole serving/suggested portion size
- Use total carbohydrate per serving/portion size
2. Weighing food portions
- Most accurate way to measure carbohydrate intake
- Useful for rice/pasta/cereal/potatoes/recipes
- Use digital scales for greater accuracy
- Use ‘per 100g’ information from labelling
- Calculate using formula or use Carbohydrate calculator table
3. Carbs and Cals Reference Tables/Apps
- Useful when eating out/food without labelling to estimate carbohydrate content
4. Handy measures
- Useful for foods you eat regularly
- Foods without labelling
Reading labels
All packaged food has nutritional information on the back or side of packaging. This shows the main nutrients, including energy (kcal), protein, carbohydrate and fat. This is usually given per 100g/100ml and sometimes per portion. Using this nutritional information is the quickest, easiest and most accurate way to count carbohydrate.
Carbohydrate on food labels
Nutritional labels often show different carbohydrate details.
Carbohydrate can be noted in one, two or three parts:
- Carbohydrate (always included)
- of which sugars (often included)
- of which starch (sometimes included)
When you are counting carbohydrate, you must always use the ‘Total carbohydrate’ figure either per 100g or per portion (1). This will be the largest carbohydrate figure shown and includes both the ‘of which sugars’ and ‘of which starch’ amounts.
Nutritional labels often tell you the carbohydrate content per suggested portion or serving size. This figure works well for foods like biscuits, crisps, yoghurts and ready meals where you tend to eat the recommended amount.
However, if you have a different portion size, you will need to calculate the amount of carbohydrate in your serving. This is common for foods like pizza, pasta, breakfast cereal and desserts.
1. Suggested serving or portion
Servings or portions are often described differently depending on the type of food, how it is prepared and served.
- Packaged food is often described by quantity or a number of pieces, such as a slice of bread, a tub of yoghurt, 3 fish fingers, 5 crackers, potato wedges.
- Foods we cook then share, are often described as fractions, for example ½ pizza, ¼ pie, ⅛ cake.
- Weight is used for foods that we eat in varying amounts such as 40g of cereal, 140g of rice, 160g of pasta.
If you want to eat a different number of pieces of food than in a suggested serving or portion:
- Work out how much carbohydrate is in one piece/unit.
- Multiply this amount by the number of pieces you are going to eat.
Look through the following examples and then try with some of your own food choices and labels to practice:
Wholemeal Bread-
|
Typical Values |
Per slice |
Per 100g of product |
|
Energy |
102kcal |
218kcal |
|
Carbohydrate |
19.8g |
42.0g |
|
of which sugars |
1.3g |
2.8g |
|
Fat |
1.1g |
2.4g |
If you ate 2 slices of bread, you would need to multiply the amount of carbohydrate in one slice of bread by 2.
19.8 x 2 = 39.6g of carbohydrate
We often share foods like pizza, pasta bake, puddings or cakes. The examples below show you how to apply the same steps to calculate how much carbohydrate is in your serving.
The label below shows the nutritional values for 100g and for 1/6 of a cake.
You are going to have a 1/8 of the cake. You can work out how much is in your slice by following the steps below:
Victoria Sponge Cake-
|
Typical values |
Per portion (⅙ cake) |
Per 100g |
|
Energy |
230kcal |
405kcal |
|
Carbohydrate |
31.6g |
55.5g |
|
of which sugars |
18.6g |
32.6g |
|
Fat |
10.0g |
17.6g |
- Work out how much carbohydrate is in the whole cake. Multiply the carbohydrate in the 1/6 cake portion by 6 to work out the carbohydrate in the whole cake.
31.6 x 6 = 189.6g carbohydrate
2. Work out how much carbohydrate is in your slice (1/8 cake).
Divide the total carbohydrate in the whole cake by 8 to work out the carbohydrate in 1/8 cake
189.6 ÷ 8 = 23.7g carbohydrate in your portion
2. Weighing food portions
When having loose foods such as breakfast cereal, rice, pasta and fruit, the most accurate way to count carbohydrate is to weigh your food then calculate its carbohydrate using the ‘per 100g’ value on nutritional labels or reference tables.
What you need:
- Digital kitchen scales that weigh to the nearest 1g
- Calculator
- Notebook and pen
To calculate the carbohydrate in your portion:
- Weigh your portion.
- Look at the label and check the amount of carbohydrate per 100g of product
Remember:
Use the total carbohydrate per 100g figure on the food label. NOT the ‘of which sugars.
3. Divide the carbohydrate ‘per 100g’ figure by 100 to tell you how much is in 1g.
4. Multiply this amount by the weight of your portion to tell you how much carbohydrate is in your portion.
(Carbohydrate per 100g ÷ 100) x weight of your portion = carbohydrate in your portion.
Use a calculator to help you – this will avoid confusion and help complete calculations accurately and easily.
Look at the following example then practice with your own foods to build your confidence and skill. It is also helpful to weigh your portion then find a useful easy measure to keep your serving size consistent, for example the same serving spoon or cup.
Example calculation:
100g baked beans contains 14g of total carbohydrate.
If the portion weighs 80g then carbohydrate content = (14 ÷ 100) x 80 = 11g
If the portion weighs 220g then carbohydrate content = (14 ÷ 100) x 220 = 31g
Now work out each of the individual foods in a meal and add them up to get the carb content of the whole meal. This would be the same process if carb counting a recipe.
Once all counted, round up or down to the nearest 5g or 10g (Use 5g if you have a ½ unit pen).
3. Carbs and Cals Reference Tables/App
- Contains food photos with carbohydrate contents for a variety of portion sizes
- Useful when eating out or for foods without labelling
- Also useful for carb content of cooked food portions, such as, pasta, rice or noodles.
4. Handy measures
Useful for foods you eat regularly or foods without labelling, for example:
- 1 tablespoon pasta/rice =10g carbs
- 1 medium egg sized potato = 10g carbs
- 2 tablespoons baked beans = 10g carbs
- A fist is approx. 1 cup (ice-cream/cereal) = 30grams carbs
Tips
- Start with an easy meal to build your confidence.
- Keep a notebook to write down your usual foods, snacks and drinks.
- Weigh and record your portion sizes. Make a note of a handy measure to replicate the portion if possible.
- Make a note of the label information per 100g, this can be useful in case you discard the packaging.
- Calculate and note the carbohydrate count for your portion.
Food diary
Keep a diary for a week of the foods and drinks you have had and their carbohydrate content using the Food Diary provided. The more detail you can provide the better. When this Food Diary is complete, please return to the Dietitian so your insulin to carbohydrate ratio can be reviewed.
Contact Details
Diabetes Specialist Nurses: 07973704946
Diabetes Team email: fhft.
Paediatric Diabetes Dietitian:
Contact Tel: 0300 613 4053
Resources
Books:
Carbs and Cals: A visual Guide to Carbohydrate and Calorie Counting for People with Diabetes. Chris Cheyette and Yello Balolia. Photographs of different portion sizes showing carbohydrate and calorie values for each.
ISBN: 978-0956443052
Collins Gem. Calorie Counter. Values per 100g and per portion.
ISBN: 978-0007211500
Available from online retailers or can be ordered in bookshops.
Phone App:
Carbs and Cals is also available as an App for I-phones and androids via the app store.
Some families also use MyFitnessPal, MySugr App or other fitness/nutrition apps
DEapp also has a section on Carb counting
Online learning:
Carbohydrate counting video link:
https://www.cypdiabetesnetwork.nhs.uk/national-network/carbohydrate-counting/
Bournemouth E-learning website (this is designed for adults but easy to master for teenagers/parents)
Contact us
If you have any queries relating to this information, please contact the Dietetics service.
About this information
Service:
Dietetics
Reference:
DT/073
Approval date:
21 May 2026
Review date:
1 May 2029
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Important note
This page provides general information only. It is developed by clinical staff and is reviewed regularly every 3 years for accuracy. For personal advice about your health, or if you have any concerns, please speak to your doctor.