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How to Count Carbs: 7 Tools Every Diabetic Should Know

how to count carbs woman eating healthy food

Carbohydrate counting is a crucial part of the diabetic diet. Tools to manage carbs should be used by everyone with diabetes or pre-diabetes because controlling blood sugar levels is fundamental to treating the disease.

Not all carbohydrates are evil. In fact, studies show that carbs like whole grains, fruits and vegetables are beneficial to our health in many ways (1). The goal is to make sure you're getting the right type and amount of carbs. 

How Many Carbohydrates Should You Eat? 

Everyone may have variations in their daily carbohydrate goals as each individual has a unique metabolism, activity level, body composition and lifestyle.

Because everyone is different, it’s important to work with your doctor or diabetes educator to confirm the right amount of carbohydrates you should be eating.

In general, healthy adults should consume about 135g of carbs (9 "carb servings") daily and diabetics should almost never exceed 200g of carbohydrates (13 "carb servings") daily (2). 

Get an idea of how many carbs you need with our free carb calculator.

Types of Carbohydrates

Not all carbs are created equal. 

There are three types of carbohydrates: 

  1. Sugars
  2. Starch 
  3. Fiber

Green vegetables are an example of foods with higher fiber. They also provide a very rich nutritional value for very low calories. And cakes, cookies and candy is made mostly of sugar carbs. These provide very little nutritional value for very high calories leading to weight gain and poor blood glucose control. Some foods that are primarily composed of protein and fat don't contain any carbohydrates. 

1. How to Calculate Net Carbohydrates

Because fiber is so good for us, some people refer to net carbohydrates, or "net carbs", when carb counting. This allows us to include plenty of healthy carbohydrates that are packed with vitamins,minerals and fiber in our diet.

Net Carbohydrates = Total Carbohydrates - Fiber - Sugar Alcohols

2. How to Count Carbohydrate Servings

1 Carbohydrate Serving = 15 grams of Carbohydrates 

This means that if a food item has 30g of carbohydrates, it has 2 servings of carbs.

Carb counting involves adding the total number of carbohydrates you have eaten and dividing this number by 15 to get the total number of carbohydrate servings. 

3. What is the Glycemic Index? 

A central goal in the treatment of diabetes is minimizing the fluctuation of blood glucose. When carbohydrates are eaten they cause a spike in blood glucose. But not all carbohydrates are created equally or cause the same rise in blood glucose. 

The American Diabetes Association recommends diabetics use the Glycemic Index (GI) to help diet planning for blood glucose control. 

The Glycemic Index is a ranking system that compares carbohydrates to show what their impact on your blood sugar will be.

Each carbohydrate is assigned a GI from 0 to 100 based on how much they will raise blood glucose after eaten.

Some carbohydrates (ie: white bread) that have a high likelihood of raising blood glucose will have a very high glycemic index, while other carbohydrates (ie: rolled oats) that have a lower likelihood of raising blood glucose are assigned a lower glycemic index. 

Foods without any carbohydrates (ie: meats and fat) aren't assigned a glycemic index because they don't cause large spikes in blood glucose. 

Studies show that diets with an overall low GI help to prevent diabetes from developing and help to control glucose in people who already have diabetes, thus preventing many complications of diabetes.

Additional research suggests that low GI diets offer other benefits including improved cholesterol and lowered risk of heart disease (3).



Low Glycemic Index Foods

(GI < 55)

Medium Glycemic Index Foods

(GI 56-69)

High Glycemic Index Foods

(GI > 70)


Corn Pasta

White Bread 


Potato (boiled)

Long Grain White Rice

Many Fruit & Vegetables

Sweet Corn

Yam (peeled & boiled)



Cornflakes Cereal

Factors Influencing Glycemic Index

  1. Carbohydrate Type
    The composition of each carbohydrate can influence the GI. Compounds called amylose and amylopectin are both in carbs. In general, carbs with higher amylose content have a higher GI while carbs with higher amylopectin have a lower GI.
  2. Sugar Type
    The type of sweetener in foods affects the glycemic index. Fructose has the lowest GI (19) while maltose has one of the highest GI (105). 
  3. Food Ripeness
    Fruit and vegetables that are not as ripe have a lower GI than those that are more ripe.
  4. Cooking Time
    In general longer cooking times leads to a higher GI.
  5. Refining
    Highly processed foods usually have higher GI.

Foods with Lower Glycemic Index Tend to Include At Least One of the Following: 

  • High Fiber 
  • High Fat
  • Limited or No Processing
  • Less Cooked

Just because a food has a high glycemic index, doesn't mean it's bad for you. In fact some high GI foods have more nutrients than low GI foods. Small portions of nutrient rich foods with a high GI can be balanced with other lower GI foods to keep your blood sugar under control.

Glycemic Index Limitations 

While glycemic index is a ranking system that helps to determine which carbohydrates have the greatest influence on blood sugar, it doesn't address how much of the carbohydrate has been eaten - aka the portion size. It also doesn't take into consideration the nutritional value of the food item. For full meals containing multiple carbohydrates, the GI can also be difficult to calculate. 

Bottom Line: Knowing the GI of a food equips you with additional information you need to help minimize large spikes in blood glucose. However, glycemic index alone doesn't provide the whole story to your nutritional needs as it does not include portion sizes or nutritional value. 

5. Glycemic Load 

Glycemic load (GL) was developed to include portion size into the equation. It takes into account both the glycemic index of a carbohydrate and how much you eat in grams (g). 


Low Glycemic Load Foods

GL < 10

Medium Glycemic Load Foods

GL 11-19

High Glycemic Load Foods

GL > 20 

Legumes (33g)

Oatmeal (250g)

Corn Pasta (180g)

Apple (120g)

Honey (25g)

Long Grain White Rice (150g)

Barley (150g)

Potato (150g)

Yam Peeled & Boiled (150g)

Carrots (80g)

White Bread (30g)

Conflakes Cereal (30g)


Both the type of carbohydrate and the portion size of that carbohydrate matter. 

A daily glycemic load less than 100 is considered a low glycemic index diet. 

You can use this database to look up the GI and GL of any food. 

6. Exchange System 

The diabetic exchange system is an approach to achieving a balanced diet by breaking up food types into 6 groups. Various food types can be exchanged for eachother within these 6 groups based on their nutritional value, carbohydrate and calorie counts. 

This system works best for people who like structured meals as it involves careful measuring and often involves 3 meals a day and one snack. 

Read more about the exchange system in this article: Food Exchange Guide for Diabetic Meals. 

7. Plate Method 

The plate method is another tool that can help control both carbohydrates and calorie intake. It works well for people who don’t want to carefully measure out their meals and is more of an ‘eyeball’ approach.  

Mentally divide a 9-inch plate into three sections.  

  • ¼  of the plate should be filled with lean protein (ie: fish, chicken, tofu).
  • ¼ of the plate should be filled with healthy carbohydrates (ie: whole grains, sweet potatoes)
  • ½ of the plate should be filled with non-starchy vegetables (ie: broccolli, cabbage, lettuce) 

Portion control is hard for most of us. The plate method approach can help us to make good choices on the serving size of each major food group, including appropriate carbohydrate intake (4).

Everyone may have a different preference to carb counting. Some use one tool, others use a combination or all of them in their daily diet. What matters is that you’re using some approach to effectively control your carbohydrates and meet your personal needs. 

Bottom line: Incorporating carb counting into your meal plan by using one or all of these tools is a critical component to successfully treating diabetes. 


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