How to adjust carbohydrate intake

How to adjust carbohydrate intake is the third article in this short series dedicated to this important source of fuel for physical activity.

We have described what are carbohydrates and the use of carbohydrate for sports. In theory, carbohydrate requirements can be calculated knowing a few variables, however in practice there is often a mismatch between estimated and actual requirements.

Sources of mismatch

Wrong calculations

• Wrong formula, e.g. using a formula designed for endurance athletes for an Olympic weightlifting athlete
• Wrong weight used, e.g. not adjusting calculations to current bodyweight

Biological factors

These include insulin sensitivity and glucose oxidation rates, which will determine how much carbohydrate the athlete can actually use for fuel.

Health conditions

• Diabetes (type 1 and 2) and insulin resistance, in which carbohydrate metabolism is altered
• Gut-related conditions, including irritable bowel syndrome (IBS) due to intolerance to specific types of carbohydrate

Actual vs predicted output

In many cases, this is the biggest source of mismatch. Some athletes can predict with a high degree of accuracy how much carbohydrate they will need for their event (e.g. endurance athletes). However, other sports/sessions are more unpredictable (e.g. team sports, martial arts, coach-led strength and conditioning session). Moreover, you might have physical, emotional or resource constraints that may alter the intensity and duration of your session. Maybe you need to train lighter because you are nursing an injury. Maybe you are very stressed and decide to just “go through the motions” to stay sane. Maybe you have a family emergency and have to cancel your session.

How to adjust carbohydrate intake

Now that you know what can go wrong, you probably realise most of your athletic endeavours will happen in the “exception” bucket, rather than the “norm”. This means your perfectly crafted meal plan will not necessarily be applicable, and that’s fine. Below are some tips to adjust your carbohydrate intake to real life if/when you are uncertain about your actual requirements.

Before

When planning your intake, aim for the lower end of the spectrum. E.g., if your session requires 3-5g carbohydrate/kg bodyweight, build your meal plan based on 3g/kg.

During

Carbohydrate during exercise is warranted for events lasting 60-90 minutes as a minimum. During the event, aim for the lower end of the spectrum (e.g. 30g per hour) and adjust your strategy based on output. If you find yourself covering more ground than you thought and/or going faster than you thought, up your intake to the higher end of the spectrum (60+g per hour).

After

This is the best time to make up for potential deficits. While after the event is too late to provide optimal fuel for performance, it is important to remember that carbohydrate intake in this window has an important role to play in recovery and preparation for the next training session or competition.

How to adjust carbohydrate intake – practical considerations

The easiest way to adjust carbohydrate is to choose meals where the carbohydrate is a separate component, rather than an integral part of the dish.

You will get more control by preparing your own meals, but this approach can also work with pre-made meals. Just make sure you choose options that are have less carbohydrates so that you can adjust upward.

More customisable options

• Sample main meals: stir-fry or curry with rice, steak or fish with mashed potatoes, roast chicken with roasted potato and sweet potato.
• Sample breakfasts: eggs on toast, cereal with milk and/or yoghurt, porridge with milk and/or yoghurt.
• Sample snacks: smoothie with fruit and milk or protein powder, unsweetened yoghurt and fruit, nuts and fruit.

In all these meals you can adjust the carbohydrate amount by adjusting the amount of carbohydrate-rich component (in bold).

Less customisable options

• Sample main meals: pasta dishes where the sauce is mixed with the pasta (e.g. lasagna) and pastry/dough based dishes (e.g. meat pie, pizza).
• Sample breakfasts: banana bread, pastries, commercial breakfast beverages.
• Sample snacks: baked goods, yoghurt with added sugar, muesli bars.

The amount of carbohydrate will depend on the actual food/food product you are using, but below are some approximate numbers:

Food	Quantity	Carbohydrate (g)
Bread, white, commercial, fresh	1 regular slice	16.31
Bread, soy & linseed, fresh	1 regular slice	10.86
Bread, sourdough, white, commercial, fresh	1 regular slice	17.07
Breakfast cereal, corn based, flakes	1 cup	22.11
Sanitarium Weetbix	2 biscuits	20.10
Rolled oats, cooked, with water	1 cup	24.03
Banana	1 medium	19.21
Apple, red skin, unpeeled	1 medium apple	20.24
Orange	1 medium orange	10.74
Kiwifruit, green, peeled	2 fruit	14.20
Mandarin, fresh	2 medium	14.70
Strawberries, fresh	1 cup	9.75
Blueberries, fresh	1 cup	15.12
Rice, white, cooked	0.5 cup	34.20
Potato, mashed, homemade, with milk & butter	1 cup	24.16
Potato, peeled, baked, olive oil	1 medium potato	22.49
Sweet votato,orange, peeled, roasted	0.5 medium	28.10

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