Coeliac / Gluten Free, Type 1 Diabetes

Why you have to be good at Maths to count carbohydrates!

When Cian joined the Comprehensive last year, he was really looking forward to Home Economics and making gluten free treats for Fin.

It turns out that in Year 7, you are not able to take in your own ingredients and you are simply expected to take in 50p per lesson in order for the teacher to provide you with the necessary ingredients.

After bringing home Tupperware containers of what can only be described as “gluten filled slop” all year, last year, Cian was excited to announce that in Year 8, he could take in gluten free alternatives to the ingredients list they were provided with in the lesson.

This week they were making flapjacks and the ingredients were quite straight forward.

150g Porridge Oats

75g Caster Sugar

75g butter

A tablespoon of honey

Prior to sending in the sponge cake tin that was requested, I weighed it and recorded the weight as 208g. The reason for this will become clear later on.

This afternoon, Cian came home with his flapjack and before we could tuck in, we had to calculate the carbohydrates to be able to decide how much insulin Fin would need for his portion.


Fin wanted to help and so armed with a pen, paper and calculator he was ready!

The ingredients and their nutritional information were as follows:



There are 59g of carbohydrates in 100g of porridge oats. There was 150g of porridge oats in the recipe and so the carbohydrates are worked out as follows:

59g carbs / 100g x 150g = 88.5g of carbs rounded to 89g



There are 100g of carbohydrates in 100g of caster sugar.

There was 75g of sugar in the recipe and so the carbohydrates value is also 75g.

(100g carbs / 100g x 75g = 75g of carbs)



There are 84g of carbohydrates in 100g of honey.

There was 15g of honey in the recipe and so the carbohydrates are worked out as follows:

87g carbs / 100g x 15g = 13.05g of carbs rounded down to 13g

The carbohydrates in the butter were 0.6g per 100g so did not need to be included.

We then totalled all elements to obtain the total value of carbohydrates for the whole flapjack.


Honey – 13g

Oats – 89g

Sugar – 75g

Total amount of carbohydrates for the whole flapjack totalled 177g.

We then needed to find out the weight of the flapjack.

We weighed it in the tin and found it to be 400g in weight.


We then took off the weight of the empty tin (208g) which I had weighed the day before.

This made the weight of the total flapjack, excluding the tin, 192g.

We then weighed a slice out for Fin……


….. and worked out the carbohydrates for his portion.

177g of carbohydrates in the total flapjack divided by the total weight of the flapjack (192g) x portion size of 21g.

177g / 192g x 21g = 19.35g of carbohydrates (rounded down to 19g)



So that’s it, easy!!

It would be much easier to have gone to the shop and bought ready made flapjacks with the carbohydrates on the back but where’s the fun in that!

And in any case, now I have one kid who thinks he is the next Gordon Ramsey and one who thinks he has a future career on Countdown!


And as long as they are happy, I’m happy!

Beth xx

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