Carb counting is the golden standard when it comes to maximizing glycemic control while expanding food choices.
Sure, you can get away with a preset insulin dose or arbitrarily guessing how much insulin to take for your usual meals and snacks, but carb counting allows for a much higher level of finesse when you are trying varying amounts of carbs and different foods outside your usual comfort zone.
If you enjoy eating the same foods all day, every day, then not knowing how to carb count isn’t a big deal. But the majority of people (with or without diabetes) enjoy venturing outside the daily same-ole routine, trying new experiences, and living life!
With diabetes, trying a new food can become a daunting event because you are unsure of how it will affect your blood sugar. Learning to carb count can be freeing because it allows stability during times of uncertainty.
In this article, I will cover how to carb count, the available tools and apps that can help you, how to “guestimate” carbs when you are eating out, and how to account for protein and fat before calculating your insulin doses.
How to carb count
Carb counting can seem overwhelming at first, but the basic concept is not difficult and access to modern apps and other tools has made it even easier.
Step 1: Identify the total amount of carbs
The nutrition label is a great tool to easily find not only the total number of carbohydrates in each serving, but also the type of carbohydrates, such as sugar and dietary fiber.
To figure out how many carbohydrates are in a food with a nutrition label, you first need to identify the serving size. The calories and nutrient amounts shown on a label refer to this single serving size.
It’s important to identify the serving size because the amount that fills you up may be substantially larger than the prescribed serving size listed on the label.
To add up the carbs when you have access to a nutrition label, use the following:
- Identify the serving size
- Look for the total carbohydrates
- Multiply the total carbs by the number of servings you will consume
If you don’t have access to a nutrition label (for fresh produce for example), you can use a list of common foods and their carbohydrate content or one of the many available food tracking apps. We will get back to that later in this post.
Step 2: Subtract for fiber and sugar alcohols
Man-made fiber and sugar alcohols are common ingredients found in many protein bars, shakes, and other various “low carb” products.
Simply put, dietary fiber refers to the nutrients in the diet that your gastrointestinal enzymes cannot digest. If you cannot digest a nutrient, the nutrient cannot raise your blood sugar, therefore you do not have to take insulin when you eat that said nutrient (fiber).
You therefore need to subtract fiber from the total carbohydrate count to calculate the total number of carbs that do raise blood sugar. This process is known as calculating the “net carbs” of a food.
The formula for net carbs is to subtract the fiber (and half of any sugar alcohols if present) to get the total net carbs that raise blood sugar and thus require insulin.
The reason sugar alcohols need to be divided by half before being subtracted is due to sugar alcohols being only partially digested. With partial digestion, your blood sugar will still rise, but not to the same degree as regular sugar.
As a rule of thumb, if your food serving contains less than 5 grams of fiber, my advice is not to worry about subtracting. If your food contains sugar alcohol, I recommended dividing that total number by two and subtracting from the total carbohydrates. If the food has a substantial amount of fiber and sugar alcohols, you can use the following formula.
|Net carbs = Total carbohydrates – fiber (if greater than 5 grams) – (sugar alcohols / 2)|
Note: There are many different opinions on how much fiber to subtract to find the net carbs. Some people only subtract 50% of fibers or even less. You will have to do a little trial and error to find the amount that’s right for you.
How to account for protein and fat
When you eat carbs, they are absorbed and rapidly increase the amount of glucose in your blood.
When you eat protein, you will likely experience a delayed, yet more prolonged increase in blood sugar due to the conversion of amino acids to glucose through gluconeogenesis. Gluconeogenesis is the formation of glucose within the body from substances other than carbohydrates, such as amino acids from proteins, glycerol from fats, or lactate produced by muscle during anaerobic exercise .
Somewhat similar to protein, dietary fat results in a delayed rise in blood glucose due to an impact on cellular responses that causes increased insulin resistance . Consuming fat will also delay the rate of stomach emptying which also adds to the prolonged postprandial (after meal) spike in blood glucose levels .
When combined with carbs, protein and fat typically soften the blood sugar rise, but then prolong the postprandial spike and increase overall insulin resistance (AKA make your correction factor not work as well).
On average, someone with diabetes will likely need to increase their insulin dose with an additional 30% for a meal that is high in protein and an additional 60% for a meal that is high in protein and fat . However, the actual dose needs to be tailored to the amount and method that works best for you.
The takeaway here is that while carbohydrates are the main macro that raises your blood sugar, you need to consider how protein and fat not only also raise your blood sugar, but cause a prolonged spike, and increase insulin resistance anywhere between 3-8 hours after a meal.
The lower the amount of carbs in your diet, the higher the fat and protein amount, the more you will see prolonged postprandial spikes and increased insulin resistance. This isn’t necessarily a bad thing, but a trend you should be aware of so you can make the necessary adjustments for better blood sugar control.
The Diabetic Exchanges (list of common foods)
The Diabetic Exchange List was created to simplify carb counting. A diabetic exchange is the serving size of a starchy food that constitutes about 15 grams of carbohydrates. Below is a list of common diabetic exchanges. To access the full list, click here.
Don’t feel that you need to memorize every diabetic exchange. Print off the list, highlight the foods you like and eat most frequently, then put the list where you will see and can review often.
Diabetic Exchange List for Common Carbohydrate Sources
1 serving equals about 15 grams of carbohydrates
- 1 slice bread (1 ounce)
- 1 tortilla (6-inch size)
- ¼ large bagel (1 ounce)
- 2 taco shells (5-inch size)
- ½ hamburger or hotdog bun (1 ounce)
- ¾ cup ready-to-eat cereal
- ½ cup oatmeal (cooked)
- 1 cup broth-based soup
- 4-6 small crackers
- ⅓ cup pasta or rice (cooked)
- ½ cup starchy vegetables (such as peas, corn, potatoes, and winter squash), beans, or legumes (cooked)
- ¾ ounce pretzels, potato chips, or tortilla chips
- 3 cups popcorn (popped)
- 1 small fresh fruit (4 ounces)
- ½ cup canned fruit
- ¼ cup dried fruit (2 tablespoons)
- 17 small grapes (3 ounces)
- 1 cup melon or berries
- 2 tablespoons raisins or dried cranberries
- ½ cup fruit juice
- 1 cup fat-free or reduced-fat milk
- 1 cup soy milk
- 2-inch square cake (unfrosted)
- 2 small cookies (⅔ ounce)
- ½ cup ice cream or frozen yogurt
- ¼ cup sherbet or sorbet
- 1 tablespoon syrup, jam, jelly, table sugar, or honey
Carb counting apps
There is an ever-growing number of mobile apps that can help you count carbs. Some of them are just food databases while others are more interactive diet tracking systems. Here are four of some of the most popular carb counting apps:
While these apps are generally accurate, some of them accept user-generated info in their databases, which may not always be reliable (e.g. people can enter the nutrient data for their favorite restaurant foods themselves).
Always use common sense when looking at the carb counts and judge if the numbers seem right before dosing your insulin.
Learning the art of guesstimating
In today’s world, we have easy access to the carb counts of our favorite foods using our smartphones. The issue however is when we are eating at a friend’s house or some hole-in-the-wall restaurant.
No worries though, by memorizing your favorite diabetic food exchanges, the next step is to learn a couple measuring tricks so you can guesstimate the total carb amount of your meal.
Guesstimating = Guess + Estimating
The secret to learning how to measure in unknown situations is to use your hand to size up your food. Generally speaking, a regular-sized hand is equivalent to the following . . .
- Clenched fist = 1 cup.
- Thumb (base to tip) = 1 tbsp
- Thumb tip = 1 tsp
- Handful = 1 oz
Of course, hand sizes vary so to make this trick work, be sure to compare your fist to an actual measuring cup before using your hand as a measuring device. Learning to size up your food will take practice, and perhaps even a bit of physically comparing your clenched fist to a mound of rice or pasta at dinner.
By knowing your favorite diabetic exchanges and being able to eyeball your portion sizes, the next step is to add everything up to estimate your total carb count.
For example, let’s say you ate the following:
- 1 cup of rice (or about 1 clenched fist)
- 3 oz chicken covered in teriyaki sauce
- 1 cup steamed broccoli
- 1 fortune cookie
Let’s break it down
- ⅓ cup of rice = 15 grams [15 x 3 servings (3 servings per cup)] = 45 grams
- 3 oz chicken = ~0 grams
- Teriyaki sauce = ~10 grams (guestimating here)
- 1 fortune cookie = ~7 grams (you looked it up on your phone)
45 grams + 10 grams + 7 grams = ~62 grams of carbohydrates.
You would then either enter the total grams into your insulin pump or divide into your carb ratio calculated for you by your provider or diabetes educator.
Count the carbs that matter to YOU
In this article, we have covered tips on counting all carbs, but, you do not need to know the carb counts for every piece of food on the entire planet, just the foods YOU like. If you think about it, we often stick to the same 20 foods or less, which makes carb counting much more feasible.
An easy way to learn the carb counts of your usual foods is to use google docs or word (or you can always go the old-fashioned route with pen and paper) to create the following chart.
- Column 1 = Food
- Column 2 = Content and Amounts
- Column 3 = Carbohydrate Count (grams)
Here is an example of what an entry for a turkey sandwich could look like.
|Turkey sandwich||2 slices wheat bread||~30 grams|
|3 slices of turkey||~3 grams|
|2 slices lettuce||~2 grams|
|1 slice of cheese||~0 grams|
|2 slices tomato||~2 grams|
|½ tsp mayo||~1 gram|
|Total =||~38 grams|
You can add multiple meals and snacks so that you have a detailed reference sheet in place for all your go-to meals. After referring to your chart for a week or so, you’ll quickly become a master of the carbohydrate counts that are most important to you.
BONUS TIP: To be extra helpful with your carb counting experience, take notes on how certain foods affect your blood sugar 2 hours after eating. This can be especially helpful if you eat a lower carb diet with higher amounts of protein and fat.
Carb counting takeaways
Learning how to count carbs can be a bit challenging at first, but once you break down the rules and memorize the serving sizes and carb amounts for the foods that matter most to you, you are well on your way to making carb counting a part of your usual routine.
As you are learning how to carb count, times will be messy. However, the goal here is never perfection, but progression. We do the best we can, we learn from the highs and lows, and we move on a little wiser than before.
Understand that good control and diabetes management goes through ebbs and flows of motivation. Sometimes we are really in a groove and doing a killer job, and sometimes we feel a little burnt out and need a break. As we strive for better control as our baseline, during our periodic deviations we can still stay healthy.
Day by day, we continue to learn about our diabetes so we can live a vibrant and fulfilling life. By taking the time to take care of ourselves, we can do the things we love most and continue to share moments with our loved ones.
-  Melkonian, E. A. (2019, August 22). Physiology, Gluconeogenesis. Retrieved March 29, 2020
-  Ježek, Petr, Jabůrek, Martin, Blanka, & Lydie. (2018, June 19). Fatty Acid-Stimulated Insulin Secretion vs. Lipotoxicity. Retrieved March 31, 2020
-  Paterson, M., Bell, K.J., O’Connell, S.M. et al. The Role of Dietary Protein and Fat in Glycaemic Control in Type 1 Diabetes: Implications for Intensive Diabetes Management. Curr Diab Rep 15, 61 (2015)
-  Smart, C. E. M., King, B. R., & Lopez, P. E. (2020, January 1). Insulin Dosing for Fat and Protein: Is it Time? Retrieved March 28, 2020