Is a no-carb diet good for runners?

Dieting while running can help with weight loss if done correctly. But a No Carb Diet?  Is that good for your body while you are training for a marathon?

Carbohydrate science

To answer these questions let’s go through a quick physiology lesson.  The body prefers to get its fuel (sugar) first from easy-to-access places in your muscles and liver as glycogen. High-intensity exercise, like speed work, will quickly burn up this glycogen causing your body to pump out stress hormones, like cortisol.  This process turns sugar into fuel.

Glycogen and no-carb diets

When your glycogen storage starts to run low, your body can also use fat stores as an energy source.  This can affect the exercise intensity or pace that you’re running. This typically isn’t an issue if you’re on an easy run, but could become an issue if you’re trying to maximize performance and speed. Your body can, over time, become more efficient at burning fat for energy.  This helps endurance running as opposed to hill climbs or speed work.

Carbs and running

Carbohydrates are very important following your training run. At this point, your body needs to replenish glycogen stores to increase your recovery. The better your recovery, the better able you are to train tomorrow and keep your energy levels high, repair damaged muscles and tissue, and maintain muscle and lose fat.

Use a no-carb diet for fast weight loss

There are many studies that show low-carb eating can help you to lose weight and improve blood pressure. Low-carb diets are much more effective than higher-carbohydrate or low-fat diets for weight loss. They help control hunger, lower food cravings, stabilize blood sugar and encourage fat burning.

No-carb diet for runners

There are tons of low-carb diets and they all vary in terms of the number of carbohydrates recommended.  When you’re on a low-carb diet, carbohydrates make up no more than 40% of your daily total caloric intake. The actual intake amounts depend on your weight loss goals.

Low carb is better for runners than no carb

For runners that want to implement this, the best approach is to follow a timed low-carb diet. Meaning you consume appropriate amounts of carbs before, during, and immediately following a training run, but focus the rest of the day on low-carb foods. This includes high-quality protein sources like meat, fish, eggs, nuts, seeds, protein powders, and vegetables. This approach enables your body to fuel your runs and recover effectively but also improve fat burning throughout the rest of the day.

Finding the right amount of carbs

The number of carbs you need will depend on the length and intensity of your training run. Prior to the run, this may mean 20 grams – 30 grams of carbohydrate intake and another 50 grams of carbohydrates during and/or within 20 minutes of finishing the training run.  This is clearly more than some of the no carbohydrate diets, that cut carbs down to around 40 grams to 50 grams for the entire day.

Timing carb intake

In practice, this means that 20 – 30 minutes before a run you may snack on some easy-to-digest carbohydrates that absorb quickly. Like a banana, cooked sweet potato, grapes, or granola bar. Energy gels like, GU or Power Gel, and sports drinks are also good options. By timing this carb intake appropriately, your body will burn this glucose to fuel your run rather than storing it as fat.

Recovery after a run

Immediately after your run, you should try to eat high glycemic foods. For the best recovery, focus on a combination of carbs at a ratio of 3 grams to 1 gram of protein. Using a good whey protein powder mixed with fresh fruit can be a quick and easy choice.  You can also have a bowl of fruit with Greek yogurt and some nuts seeds or granola.

Final thoughts on a no-carb diet

While in training for a marathon, you shouldn’t cut out carbs completely.  It could hurt more than it helps.  Lower carbs and well-timed carb consumption is a better option with the added benefit of potential weight loss.