Carbohydrates have been attacked due to causing sudden blood glucose spikes for the past 15 years.

However, the bottom line is endurance athletes like Open Water swimmers need carbs to function. And you don’t have to doing a 5 mile swim for this to be relevant. You need to fuel your body.

So what do we want to achieve?

Constant fuel available to be converted to glucose, to be converted to ATP, which the molecule that drives the metabolic process.

What we don’t want is to have insufficient food or run out of sources that can be converted to glucose, nor do we want sudden blood glucose spikes followed by deficits, nor insufficient glycogen stores in the body that can be converted to glucose.

When we digest, food is converted to glucose in the blood. Insulin levels rise and we use some and as insulin levels drop after we use this amount, we also store some in the liver, for later use. We also store some in the muscles for immediate demand by those muscles.

The average adult male glucogen load is about 400grams in the liver, muscles and cells, enough to fuel about 2 to 3 hours effort.

All this is a preamble to deciding what’s good and bad.

We all fall into patterns of eating and I am no paragon of diet. With all the training I do have a high caloric intake averaging 4 to 6 thousand calories a day, I’d guess, for Channel training.

Foods with a low glycemic index (GI) are better because the glucose is derived at a fairly constant rate. There’s also Glcemic Load, but let’s keep it simple.

I’ve been thinking about changing a few aspects of my diet.

Breakfast is always a freshly made fruit smoothie, about half a litre, now also always containing natural yoghurt AND a half cup of oats. This is a pretty high glucose load meal but at a mid level glycogen load, so no high glucose spikes. The addition of the oats reduces the nice taste though but is easier for me than eating bloody porridge,as mentioned previously. DON’T substitute processed oats like ReadyBrek as they are a much higher GI.
Natural yoghurt is a low GI food and a great additive. Low fat natural yoghurt is even better. (Low-fat cottage cheese is quite similar.)

Here’s one I hadn’t realised. Apples are better than bananas for fuelling. As a former cyclist, I’m addicted to the idea of bananas as a wonder fuel providing both potassium and carbs. Both are true. But an apple provides better carbsas they are lower GI. So a mix of both is better than either/or.

The biggest problem in my diet is overuse of potatoes. Potatoes are one of the very few exceptions to using fruit and vegetables as a source of good carbs. Pasta, even plain white, is a better choice, as is rice. I also tend to steam my spuds whereas baking is actually better (though I haven’t looked at the WHY of this yet). Actually making home-made chips is probably better than making mash. But it also dependent on the potato variety. Sweet potatoes however are a very good good, not at all like the ordinary potato generally used in Ireland.

White bread is essentially worse than potatoes , whole wheat bread is better than white and whole grain bread is better again. Multi-seed bagels are also a reasonable choice.