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An Introduction to Carb-Counting
What is a “carb” anyway?
This is one of the first questions I had when my son was diagnosed with type 1 diabetes! What qualifies as insulin-requiring carbs? And the related question: What’s NOT a carb? That is, which foods qualify as “free” foods, that we don’t have to cover with insulin? Here’s what you need to know about this key concept in managing diabetes effectively…
The three main nutrients contained in food are carbohydrates (“carbs”), protein and fat. Some foods contain all three; other foods are largely made up of one of these nutrients. For example, a steak is mostly protein with some fat, but no carb; an avocado has a high fat content with negligible protein and carb content; rice is made up mostly of carbohydrate, with a small amount of protein and only trace amounts of fat.
Carbohydrates are the part of food that has the most effect on blood glucose levels. When you eat, your digestive tract breaks down carbohydrates into simple sugars (namely, glucose) that are small enough to be absorbed into the bloodstream, and then into the cells for energy. When calculating insulin doses, it is the carb content of food that we take into account; our goal is to match the insulin dose to the carbohydrate content of the food (according to an Insulin:Carb Ratio), striving to hold blood glucose as steady as possible following a meal or snack.
Which Foods Contain Carbs?
Many foods contain enough carbohydrate to affect blood sugar, including:
Which Foods Do Not Contain Carbs?
There are a number of foods that contain no carbs, or little enough carbs that they do not significantly affect blood glucose. These “free foods” can be eaten (in moderate amounts) WITHOUT having to give your child insulin. For example:
More low carb options:Low Carb Snack Ideas
How Do I Figure Out the Carb Content?
There are a number of methods for determining how much carbohydrate a given food contains:
1. Food Labels
All packaged foods must include a nutritional label, which specifies, among other things, the grams of carbs in that food.
2. Nutritional Scales
While a “kitchen scale” simply tells you the weight of the food, and a “digital scale” simply provides the weight in digital format, nutritional scales are electronic devices that measure the weight of the food you enter and then, based on this weight plus the nutritional information contained in their internal database, calculate and display the carbohydrate content for you. They also display other nutrient information…
3. Nutrition and Carb Books
Beyond The Basics is a resource put out by Diabetes Canada (formerly the Canadian Diabetes Association, CDA), which The Alberta Children’s Hospital provides for newly-diagnosed patients in binder format. Beyond the Basics may be accessed online via the Diabetes Canada website.
Other carb-counting books include: Calorie King (US resource), which gives the calories, fat and carbohydrate content for a variety of foods (including grains, breads, fruits/vegetables, meats, beverages, packaged foods, and restaurant foods).
4. Rules of Thumb
You may find it useful to write a note, print this out for your fridge, or memorize a few of the following guidelines for common carb-rich foods (NOTE: these are not exact carb counts):
*units are grams of carbs
|Bread, white||1 slice||contains 15g of carbs|
|Bun/roll||1 bun||contains 25-30g of carbs|
|Sub bun||each 1" length||contains 8g of carbs|
|Bagel (and dense breads)||1 cup OR 1 bagel, 4" diameter||contains 50g of carbs|
|Pizza, regular crust||1/12 of whole||contains 16g of carbs|
|Tortilla, 6" white||1||contains 13g of carbs|
|Cupcake, small -no icing||1||contains 15g of carbs|
|Cupcake, small with icing||1||contains 25g of carbs|
|Rice||1 cup||contains 45g of carbs|
|Potato (boiled, baked)||1 medium potato||contains 30g of carbs|
|Potato (mashed)||1 cup||contains 34g of carbs|
|Legume-type Bean (kidney, black, navy, chick)||1 cup||contains 28g of carbs|
|Corn kernels||1 cup||contains 28g of carbs|
|Corn-on-the-cob||1 medium||contains 20g of carbs|
|Peas||1 cup||contains 14g of carbs|
|Pasta||1 cup||contains 30g of carbs|
|Milk||1 cup||contains 12g of carbs|
|Juice||1 cup||contains 30g of carbs|
These guidelines may also be helpful when you don’t have a scale available, or when you need to visually estimate carb content, such as when you are out for a meal.
5. Smartphone Apps
Most fast food restaurant chains have an app available, including Tim Horton’s and McDonald’s. There are also numerous apps available available for common foods and manufactured (name-brand) foods. Examples include Calorie King, Figwee, Carbs & Cals, Track3, Calorie Counter by myfitnesspal, My Plate Calorie Tracker by Livestrong, and Carb Counter by Atkins.
Some apps, such as Figwee and Carbs & Cals, also include a visual-estimation function, so you can compare the serving in front of you to pictures of that food, with the corresponding carb content given. Handy!
We recommend you try out a few apps to see which is most relevant for your family’s needs. Some things to look for:
- Does the app’s database corresponds to the country you’re in? For example, if you live in Canada but use Carbs & Cals (which includes nutrient information from USA, UK, and other countries) then you may not be getting the correct carb values, as the nutrient content of a given food sold in Canada often differs from the same brand sold in the US. If you live in Canada, make sure the app uses Canadian restaurant and brand information.
- Many apps are labeled as “calorie” counters, because that’s what the general population is seeking for weight loss. For managing diabetes, however, make sure the app you choose also breaks down the nutrient content to give a carb count, as you will dose insulin based on carbs, not calories.
- If the app is free, it will likely prompt you to sign up for a premium version. If you find this a bother, you may want to opt for a paid app.
6. Company websites
Many large manufacturers have the nutritional information for their products on their website.
Some restaurants, especially fast food chains or franchise restaurants, may have nutritional info on site or online – ask your server or check the company’s website.
Carbs for Mixed Recipes and Home Baked Goods
You may be asking: How do I figure out the carb content for my home-made banana bread, or Grandma’s lasagna?
Although there are several recipe books and commercial foods available, many families have their favourites. Family recipes can be calculated and given a carbohydrate gram value for a serving. In the beginning, if your child is a patient at AB Children’s Hospital, your dietician will calculate recipes for you. Later, you will be shown how to do this yourself.
When you have a meal which combines more than one carb-containing food, the carb content for a given portion can be calculated by adding up the individual carb values and then dividing by the total yield, as outlined below.
To calculate the carb-content for a serving of a home-made or mixed recipe:
1. Measure and note the carb value for the amount of each ingredient in the recipe. Write it right in your cookbook or on your recipe card if you like – saves time the next time you make this recipe.
2. Add up the individual carb values to calculate a total carb value for the whole recipe.
3. Cook or bake the food as indicated, then measure the total yield of the recipe (after cooking) by either:
More info and detailed examples on calculating carb content of mixed recipes by weight and volume:
4. Divide the total yield by the combined carb value to arrive at a per-serving carb value.
For example: If the above recipe made 10 pancakes, divide 180 g carbs by 10 pancakes, arriving at 18 g of carbs per pancake.
Note: The size of the pancakes needs to be consistent for this method to work. To do this, I use a level 1/4 cup measuring cup to scoop up the pancake batter, which makes each pancake the same size.
Another method for consistent portion sizes is to combine the ingredients in a large measuring cup and note the total volume of, in this case, the batter, before cooking. Then divide by the amount you want each pancake to be. For example, if the pancake recipe yields 2 ½ cups of batter, then it will make:
10 pancakes, each using 1/4 cup of batter, and each worth 18g of carbs, or
5 pancakes, each using 1/2 cup of batter, and each worth 36g of carbs.
If the items are not consistent in size (for example, you make a batch of sugar cookies, using different shapes and sizes of cookie cutters), it will be more precise to determine the total weight of the yield and then use a carb factor for individual cookies.
What Else Do I Need to Consider for Carb Counting?
Although the carb content of a food is the main factor affecting blood glucose, there are other factors involved. If a food is digested quite slowly (such as whole grains, apples, spaghetti, fruit juice), then the affect on blood glucose will be different than that of quickly-digested foods. This relates to the concept of Glycemic Index.
Also, keep in mind (without spending too much time dwelling on it) that protein consumed in large amounts will affect blood glucose (although there is not yet a universally-accepted way of measuring this effect). In addition, some people have reported that very large meals affect their blood glucose differently than smaller meals.
There are some foods which are famous for causing other-than-expected results post-meal. The problems they pose may be related to counting carbs accurately, or to high-fat content (which creates later insulin resistance), or to a low Glycemic Index value (which suggests slower digestion of that food). In any case, there is no reason for your child to give up formerly-favourite foods just because she has diabetes – your family just needs to learn some new ways of dealing with insulin dosing when these foods are on the menu.
Pasta is problematic for some kids, and not for others. Pasta with loads of rich cream sauce may have a particularly pronounced effect. If you find that after eating pasta, your child’s blood glucose first drops low and then spikes a few hours after the meal, this is likely due to the low Glycemic Index of pasta (and/or the high-fat content of the cream sauce). Essentially, the insulin is getting in before the food is fully digested; there is too much insulin present right after the meal, and not enough insulin present later, when the glucose from the digested pasta has reached the bloodstream.
Fast Food is generally high in saturated fat, which increases insulin resistance later (that is, the body uses insulin less efficiently and so needs more insulin for the same effect), resulting in high blood glucose readings in the hours following a high fat meal (especially overnight). You may see higher blood glucose readings for several hours after your child eats fries, hamburgers, chicken nuggets and other deep-fried foods.
Pizza can be problematic, for a couple of reasons:
1. It is often tricky to accurately determine the carb content of a slice of pizza. Initially, it may be helpful to go only to restaurants which make carb info available – this takes one variable out of the equation. Also, use nutritional scales and other measures to count the carbs as precisely as possible.
2. The high-fat content of pizza poses additional challenges, as saturated fat slows down digestion and increases insulin resistance, often resulting in high blood glucose readings several hours later.
How Can We Deal with Tricky Foods?
Soon after diagnosis, it is enough to simply be aware of this trend, so that you are not confused and frustrated by atypical blood glucose readings when your child eats these foods. Each family will decide for themselves, based on where they are in their journey with the diabetes dragon, how they want to handle this situation. Some families will avoid fast food restaurants and pizza parties initially, until they are ready to add another layer of learning. Some families will continue to eat out, but will steer their children toward healthier food choices with fewer complications (for example: chicken wraps and apple slices at McDonald’s; Subway instead of burgers and fries). Some families will choose to eat these foods and deal with the highs as they arise. (Michelle says: This is what we did for the first year or so after diagnosis, until we understood what was causing the highs.) Some families will choose to eat these foods and learn new ways of dosing/timing insulin so that the effect on blood sugar is reduced. When your family is ready to learn more, solutions to this problem may be found in other Nutrition articles on this website, such as How Fat and Protein Affect Blood Glucose.
The above information was significantly modified with permission from The Alberta Children’s Hospital Diabetes Clinic information handouts.
The above information was reviewed for content accuracy by clinical staff of the Alberta Children’s Hospital Diabetes Clinic.
This material has been developed from sources that we believe are accurate, however, as the field of medicine (in particular as it applies to diabetes) is rapidly evolving, the information should not be relied upon, as it is designed for informational purposes only. It should not be used in place of medical advice, instruction and/or treatment. If you have specific questions, please consult your doctor or appropriate health care professional.
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