How To Count Carbs: An Introduction
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 immediate 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 look at first; our goal is to match the insulin dose to the amount of carbohydrate in 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:
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.
Some grocery stores have listed on their website the nutritional information for the items they sell, so that their online customers can make informed decisions. The Real Canadian Superstore and its affiliated Wholesale Club are just two examples.
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, such as fat, protein, calories, and sometimes vitamins/minerals. (See our article on Nutritional Scales for more information).
3. Nutrition and Carb Books
Beyond The Basics is a resource put out by Diabetes Canada 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
The following general guidelines may 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. 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
|Food||Serving Size||Approximate Carb Content|
|white bread||1 slice||contains 15g of carbs|
|Bun/roll||1 hamburger/Kaiser bun||contains 25-30g of carbs|
|Sub bun||each 1" length||contains 7-8g of carbs|
|Bagel (and dense breads)||1 cup OR 1 bagel, 4" diameter||contains 50g of carbs|
|Pizza, regular crust||1/12 of a large||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|
Tips from the Trenches
We keep a running list of the foods our family eats often, with the associated carb counts noted. This list hangs beside the fridge, next to the counter where we most often prepare food. ~Michelle
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 packaged food sold in Canada often differs from the same brand sold in the US. (Fast food, as well as breakfast cereals, are especially prone to this mismatch.) 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 you google the food name and "carb" you'll get lots of hints. I would suggest comparing a few sources to arrive at a best guess, which will help you weed out inaccurate information.
7. Manufacturer websites
Many large manufacturers of packaged foods have the nutritional information for their products on their website. This information tends to be more reliable and up-to-date than third party sources, as they are most familiar with their own products and are required by law to have accurate nutritional information on them.
Tips from the Trenches
On occasion we have ended up with an individually-packaged food without the box it came in (ex. when relatives send a treat, or when a snack shows up at preschool without the original box). In this case, company websites have been very useful. I just search the item name (ex. “Kellogg Rainbow Rice Krispie”) plus the phrase “nutrition info”.
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. Like food manufacturers websites, these tend to be more reliable and up-to-date than third party sources.
Tips from the Trenches
Fear of carb-counting unfamiliar items doesn’t need to keep your family home-bound after diagnosis… Boston Pizza has nutritional info on their website – I have looked it up on my phone while waiting for our food to arrive; the manager at the Olive Garden was very helpful, printing off a copy of their nutritional info from their website while our order was being prepared; McDonald’s cites their nutritional information on their website; Cobs Bread will print off from the till the nutritional info for the items you’ve purchased.
You may need to adjust the specified amount of carbs to allow for different portion sizes than the standard size on which the info was based. For example, Swiss Chalet’s French fries are 58g (64g-6g fiber) for a 168g serving size, but we have often received a more generous portion. We carry our scale with us when we eat out so we can determine the actual weight of the portion we have received. ~Michelle
Counting 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?
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 with step-by-step details plus examples: calculating the carb-content for a serving of a home-made (mixed) recipe, including baked goods.
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 worrying too much about it soon after diagnosis - get carb-counting under your belt first) that protein and fat consumed in large amounts will affect blood glucose. 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.
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.
SHARE THIS ARTICLE