What is carbohydrate counting?

Dietitian and diabetes educator,Tammy Jardine, explains what carbohydrate counting is and how it helps in managing diabetes.

Carbohydrate counting (carb counting) is a meal planning method that allows you to match your insulin doses to the different types and amounts of carbohydrates you eat.

The carbohydrate nutrient has the greatest impact on post meal blood glucose, with a smaller and slower contribution from protein. The effect of fat is negligible.

When you eat carbohydrates, they break down into glucose. You need insulin to transport the glucose out of the bloodstream and into the body’s cells. This means that the more carbohydrates you eat, the more insulin you need.

Therefore, if you could quantify (count) the carbs in the meal and take the appropriate amount of insulin to match it, the next blood glucose should neither have risen nor fallen excessively. In other words, you are now mimicking the way the pancreas works.

By combining insulin doses based upon carbohydrate content with corrective doses, you have the opportunity at every blood test and injection of insulin to maintain normal glucose levels, or to bring errant blood glucose back into range. This reduces the fluctuation in blood glucose levels and reduces the risk of hypoglycaemic reaction from taking too much insulin when blood glucose levels are normal, or when too little carbohydrate is eaten at a meal.

Carbohydrate counting is a technique that is easy to learn and apply and offers the ability to match insulin doses with food eaten, carb counting offers flexibility in food choices that is often much appreciated. Carb counting is effective in controlling blood glucose levels and giving you flexibility.

What foods contain carbohydrates?

Carbohydrates are a nutrient found in large amount in starches, like foods made from grains: rice, maize, barley, wheat, oats, and rye; or starchy root vegetables, including potato, sweet potato, beetroot, carrots, turnip and onion. Carbohydrates are also found in dairy, fruit, legumes (beans and lentils), sugar and honey.

In a healthy meal plan, most carbs should come from nutrient-dense foods like whole grains, legumes, fruit, and vegetables. Nutrient-dense foods are high in vitamins, minerals and fibre.

Some sugary foods (cakes, biscuits, pastries and chocolate) can be included in your meal plan but should be limited (just like in any healthy eating plan) as they usually contain very few necessary nutrients.

Use common sense and indulge in moderation. Carb counting will help you decide how to include these foods in your meal plan.

Initially carb counting is a challenge as you need to identify carbs in food and how they affect you as an individual. It takes practice, trial and error, but as you persist it will come easier.

Tools to help with carb counting 

  • Measure portion sizes

It’s easy to overestimate portion sizes so it’s recommended that you use measuring cups and scales at home. Get into the habit of checking portions so that you keep portions in check. Learning portions sizes at home will help you to judge portions more accurately when you eat at a restaurant or dinner party.

When eating at home, always use the same bowl, cup, plate or glass. That way if you always pour milk to a certain point on the glass, then you know that you are eating a consistent amount of food and can expect a consistent blood glucose reaction.

Create a spreadsheet or list of foods that you typically eat at home and then look up the carb values. Then if you’re a person of habit and like to eat a certain band of cereal, you’ll always know how many carbs you’re getting.

  • Use technology

Calorie counting apps are really helpful in identifying carbs in foods. Make a list of the most common meals you eat. Some examples are MyFitnessPal, Carbs & Cals, and FatSecret. Useful websites include www.nutritiondata.com and www.eatright.org

Things to remember

Other tools include food labels, measuring tools, and recipe books. If you’re using food labels, always make sure that you’re looking at the amount of carbs in the portion that you’re eating and not only in 100g.

Pre-portion snack foods by measuring out single servings and putting them into small plastic containers or sandwich bags. This can help control your portions since it’s way too easy to keep grabbing crackers or nuts directly from the package without realising how much you’ve eaten.

Also remember that because a food says that it’s sugar-free on the label doesn’t mean that it doesn’t have carbohydrates.

Some restaurant chains will have the nutritional content of the foods on the menu so look up online so that you can make a choice before ordering.

When eating out, avoid sauces and don’t be afraid to ask the waiter how a meal is prepared or what ingredients are in the food.

For special dinners, eat the foods that are special and avoid the other foods that you can get at any time. For example, if you really love apple pie, then skip the mashed potatoes and bread at the meal and make the dessert your carb portion at the meal. Just be sure to watch your portion size.

What would you have to do?

Keep a very detailed food diary of the carb amount eaten together with corresponding blood glucose levels.

You will need to measure your blood glucose at least morning, midday and evening. If there aren’t excessive increases or decreases in the readings, then you know you have matched the insulin to carbs well.

If they are rising too much (greater than 2-4) then you know that you ate too many carbs at the previous meal and that you need to adjust either the amount that you ate or the dose of insulin that you took.

Provided that they are going lower (by more than 2-4) then you know that you’re giving too much insulin for what you have eaten at the previous meal and you need to either eat more or lower the short-acting insulin dose.

Initially, be very consistent with the amount of carbs that you eat at each meal as this will help to identify how much insulin you need for a specific amount of carbs. Knowing this will help you to be flexible with your insulin doses and adjust according to what you feel like eating.

Carb counting only influences your short-acting insulin. Your long-acting insulin will most likely stay the same and you would not adjust this insulin based on blood glucose or meals eaten.

How many carbs should you eat?

How many carbs you need is dependent on age, height, weight, level of physical activity, current blood glucose levels, and blood glucose targets. Your diabetes educator and dietitian can help you to determine this sweet spot.

Other factors to consider in carb counting

Physical activity, high fat meals and alcohol can have an effect on carb counting.

Physical activity has a various effect on blood glucose so it’s vital to monitor blood glucose to see how exercise affects you as an individual. Most people would require less insulin with a meal post exercise as exercise usually reduces blood glucose as the muscles suck up any glucose post exercise. This is individual so work with your diabetes educator to perfect this for you.

Alcohol also usually reduces blood glucose if it hasn’t been taken with sugary mixer. Keep alcohol to moderate amount (two drinks for men and one drink for women). If this seems impossible then be sure to measure you blood glucose often as symptoms of a hypo can often be confused for drunkenness. Don’t count carbs in alcohol as part of your carbs to match with insulin.

Fat slows the digestion of food in the stomach. This delay means that you may have a blood glucose level that looks fine after eating but spikes before your next meal. Sometimes a high fat meal will require a little more insulin more insulin. Work with your diabetes educator to help you with this scenario.

Step-by-step starter guide to carb counting

  1. Identify foods in carbs using tools and calculate the total of all the carbs in the meal or snack.
  2. Try to keep carbs to similar totals at each meal while your dose of short-acting (mealtime) insulin remains at a standard dose at each meal.
  3. Record your reaction to different meals so that when you eat those meals again, you can make the necessary adjustment to portion or insulin dose to create less flexibility in your blood glucose readings.
  4. Consider factors like fat, alcohol, and physical activity when you’re deciding on your insulin dose.
  5. Consider your premeal blood glucose level. You may need a bit more insulin to bring down high blood glucose. This is called a correction dose. Speak to your diabetes educator to determine this dose for you.
  6. Calculate your insulin dose considering the above factors and give the insulin dose.
  7. Record the blood glucose 2-4 hours after the meal. If it’s too high or low, consider where your calculation could be perfected.

We get over 40 different nutrients a day from food. It’s perfectly okay to eat and enjoy food. It’s just as important to also learn how to balance food, medication, and activity, so that you’re meeting your goals in managing your diabetes. What works for someone else may not work for you so identify and record how your diabetes reacts to these factors.


Tammy Jardine is a qualified diabetes educator and a registered dietitian. Living with diabetes for over 15 years means that she knows first-hand how difficult it can be to achieve and maintain optimal blood glucose control with good lifestyle habits. She believes that diabetes affects every person differently and takes the time to understand how it’s affecting the individual and to help them manage it effectively. With more than 20 years of experience working as a dietitian in the UK and SA, she has a passion for helping people live a better and happier life with good food. Tammy currently works from Wilgeheuwel hospital. Email: [email protected]

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