Adjusting Carbohydrate for Exercise


Extra carbohydrates for exercise (ExCarbs)

During most exercise (aerobic), muscles use glucose as a fuel and under normal circumstances the body makes more glucose in the liver for this to happen. With insulin use, this cannot occur if insulin levels are high as this stops the liver from being able to do this. The bottom line – carbohydrates need to be taken to balance the amount muscles are using.


One way to manage exercise is to take extra carbohydrate…but how much?


#Rule: Test blood glucose levels every 30 minutes during exercise and review




Easy Approach (based on clinical research)

Assume that muscles use glucose at a rate of 1 g for every kg a person weighs every hour. So for a 70 kg adult they will need to take 70 g of carbohydrate each hour (or 35g every 30 minutes).




Advanced approach (actually very easy as well)

Use tables which are already on the Internet (

This method is easy and works for unplanned exercise or if the exercise is more than 2-3 hours after the last insulin injection (so the bolus dose can’t be adjusted) but it may not help if weight loss is the aim.


Estimation of the EXCarbs (in grams every hour) needed to be taken with different types of exercise:


Evidence has shown that we might only be able to usefully use up to 60g carbohydrate per hour of exercise and so if we take in significantly more than this it can lead to a high sugar after exercise. Of course, everyone is different and some really vigorous exercise might need more than this but it’s the trial and error thing again of seeing what works best for you!


We have rounded all these numbers down to 60g but you can try more if 60g isn’t enough.


Activity Persons weight – 68kg Persons weight – 90kg
Cycling @ 10km/hour 27 34
Cycling @ 22km/hour 60 60
Dancing 25 33
Dancing (vigorous) 43 57
Digging 60 60
Golf 35 46
Running@ 8 km/hour 60 60
Running@ 13 km/hour 60 60
Football 60 60
Swimming 56 60
Tennis 24 45
Walking @5 km/hour 22 29
Walking @7 km/hour 45 59


These are an estimate – you need to factor in your actual weight – the heavier you are the more carbs you need, unless that is you want to use exercise to help lose weight (see Adjusting Insulin for Exercise)