Cyclists are used to carb-loading and fuelling on sugary snacks and drinks to maximize performance. Keto is almost the complete opposite. Most people on keto stay below 50 g of carbs per day, which is very different from the usual 300-500 g of carbs that a typical cycling enthusiast on a high-carb diet would eat.
How does a keto diet work?
When you reduce carbs below 50 g per day, your body switches from burning carbs to burning mainly fats for energy. That can be fat from food or your body fat stores. Burning fat for energy produces ketones and that’s the fuel that goes into your muscles and brain and keeps you going. The diet is called “keto” because of them. So, you will essentially replace the carbs you cut with fats. Your macronutrient profile on the keto diet should look something like this.
• 5-10% of the calories from carbs
• 60-75% of calories from fat
• 15-30% of calories from protein
This switch from carbs to fats has several key advantages. Here are the main four that you should know about.
Your body stores more fats than carbs
Even a very lean cyclist with 10% body fat that weighs 70 kg carries 7 kg of body fat. That is equal to something like 55,000 kcal. You can ride well over 2,000 km on that!
On the other hand, your body stores carbs in the form of glycogen. Even well-trained athletes can only store around 500 g of glycogen, which is roughly 2,000 kcal and would be enough to ride something like 80 km at best.
You experience freedom from bonking
Going keto makes your body much more efficient at burning fat. Studies show that fat-adapted athletes can burn almost 3x as much fat per minute as high-carb athletes. They can run almost entirely on fat up to 70% of their max intensity.
That means you have much better access to that big fuel tank with 55,000 kcal you’re carrying around on every ride. Especially if you’re riding very long at a low to moderate intensity, your body will be able to burn almost exclusively fat and preserve more of the glycogen. This could help you avoid the dreaded bonk because bonking is caused by running out of glycogen.
It’s easier on your digestion
You know how it goes when you’ve been riding for hours, you’re tired, and you try to force food down. Your stomach doesn’t cooperate, your digestion is slow, and all of that sugar starts fermenting. You get gas, cramps, and other unpleasant, potentially ride-ending side-effects.
The fact that you can use your own body fat as fuel on keto means that on those long endurance rides you don’t have to consume that much external fuel in a form of energy bars, gels, and so on. This could save you many digestive issues.
It can help with weight loss
Research shows that the keto diet is an effective tool for losing weight. Cutting out carbs and sugar makes it easier to reduce calorie intake and get into a calorie deficit, which is necessary for weight loss. Being in ketosis also makes you feel more satisfied after food and between meals so people naturally tend to eat less.
Getting back to race weight might be a lot easier on keto. But keto isn’t magic. All of these benefits come at a price. There are downsides to keto and it’s not always the right eating strategy. We will discuss if it’s right for you in the next article.