Fat Burning: Should I Limit Carb Intake in Long Workouts?

Velonews.com’s Chris Case answers a question that many endurance athletes ask about maximizing fat burning during long workouts. 

Do I need to control my carbohydrate intake before and during long rides in order to maximize fat burning? Or is it just the intensity that matters?
— Wang Chao

Dear Wang,
Thanks for your question. If we had to summarize sports nutrition in one word it would probably be… controversial. Or maybe just confusing. Endurance sports guidelines tell us we need to pack in the carbohydrates. Then we hear about Team Ineos and other prominent athletes resorting to a nearly carbohydrate-free diet. So which one is best, and frankly do we even need to be eating the same way a grand tour rider eats?

One thing that’s certain is that in the world of nutrition, “keto” has become a buzzword—and not only in the sports world. Terms like “ketogenic diet” have become some of the most searched dietary terms on Google. It’s even made its way to the most important forum of public opinion—the Saturday morning group ride conversation.

Now, to get to your specific question about “riding low,” meaning doing long rides without many carbohydrates for fuel, I’ll turn to our resident nutrition and physiology expert, coach Trevor Connor. Here’s what he had to say:

It used to be that some pros loved so-called “coffee rides,” not because they’d stop at a café, but because they’d wake up, drink a cup of coffee, and then do a six-hour ride on nothing but water. They liked it because it stripped the weight off, and they felt it improved their ability to burn fat—both of which are true. However, I know of one pro whose new coach stopped the coffee rides, had him do a lot of long rides properly fueled, and then he won a grand tour.

While there are benefits to the coffee ride, they are horrible for recovery and contribute to burnout. By properly fueling on long rides, this pro became better able to train harder, recover better, and ultimately become a better rider. The same would be true for you.

So, the short answer is that you will see some gains from periodically controlling carbs on your long rides, which forces your body to rely more on fat for fuel. But beware that it comes at a price. Do it carefully and sparingly. Employing it periodically in the base phase when you don’t need to be on top form can have gains. But in the heart of the season or at high-stress times when recovery is a challenge, it’s better to make sure you are properly fueled on your long rides.

Visit Velonews.com’s Training FAQ section for more cycling-specific training advice.