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Basics of carbohydrate calculation
August 30, 2021 / Nutrition / Type 1 / Type 2

Basics of carbohydrate calculation

11 min read

The most important factor which affects blood sugar is food. How much food we eat and what we eat. Food affects the amount of insulin which the body lures or the amount of insulin that DM1 have to take with injections. If the insulin and food are not balanced, we will have elevated or reduced blood glucose level.

Insulin vs. Food, food and food

On the other hand, in regards to the food we eat, carbohydrates have the biggest impact on blood sugar levels. Some food groups have more, some less, and some do not have carbohydrates at all. Oftentimes people debate over the fact if it is good to eat less or more carbohydrates, while in fact we don’t know what „less“ or „more“ means exactly. If we calculate the level of carbohydrates each one of us consume daily, it will be easier to conclude if we eat a lot, little or plenty.

Basic unit for calculating carbohydrates is 15 grams of carbohydrates. For the beginning, we can circle anything we eat at 15, 30, 45 or 60 per meal. We should not be worried by the fact that, for example, a thinner slice of bread has maybe around 13 grams and a thicker slice of bread has 18 grams of carbohydrates. We should circle it to around 15.

 15 grams of carbohydrates can be found in a spoon of white sugar or in three sugar bags for coffee. Next time when you sit for a cup of coffee pay attention to the sugar bag which you use for coffee, most of them have „netto 5 g“ written on them. So, three bags of sugar have 15 grams of sugar, and sugar is entirely a carbohydrate, which means they have 15 grams of carbohydrates. For every lunch we eat we can calculate how much „sugar bags“ we ate.

The amount of insulin is also determined in relation to 15 grams of carbohydrates. People who take insulin from injections (pens) often calculate that they need, for example, two units of insulin for every 15 grams of carbohydrates. They calculate the overall amount of carbohydrates in a meal so they can take a proper dose of insulin. People whose body produces insulin do not have to calculate it because their body does it for them. Nevertheless, many calculate carbohydrates in order to know if they ate the amount of carbohydrates which they set up for themselves, and in order to know they have not exaggerated.

 We can classify all food into one of three groups: protein, fat, carbohydrates. As an example you can see a short table of proteins, fats and carbohydrates below, and all the food is in a quantity of 100 grams in order for us to be able to compare them.

We can see from this table that milk has the equal amount of protein, fat and carbohydrates. Bread also has everything mentioned above but it has carbohydrates the most, an apple has no protein, or fat, she is pure carbohydrate. Lamb, egg and sardine have zero carbohydrates. Lard is almost exclusively fat, as we could have presumed, while for instance it is surprising that walnuts, out of all macronutrients, have the most fat.


  Protein Fat Carbohydrates
Milk 3,30 3,30 4,70
Bread 4,70 8,80 30,10
Apple 0,00 0,00 15,00
Chard 1,30 0,10 1,50
Lamb 19,00 15,00 0,00
Egg 13,00 11,00 0,00
Sardine 17,40 3,20 0,00
Walnut 10,00 51,00 5,00
Lard 0,10 99,00 0,00


This is a display of the quantity of carbohydrates per 100 grams of a certain food. This kind of a representation helps us compare and identify different types of food which have a significant share of carbohydrates on which we should pay more attention to. So, for example, we can neglect eggs and sardines but we have to pay attention to bread and apples.

If we want to know exactly how much carbohydrates do the walnuts in our bowl have, we will weigh the walnuts and then multiply by the amount of carbohydrates per 100 grams.

When a meal is evaluated, it’s easier to reverse the principle. You should base on 15 grams of carbohydrates and learn how much of certain food you can eat, with that containing 15 grams of carbohydrates. It is no coincidence that 15 grams of carbohydrates were chosen, which is for plenty of food at a practical size, so 15 grams lies in one apple, one slice of bread and one spoon of rice.

Andrijana Buklijas Skeledzija Read more posts by this author
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