There’s a complaint that you sometimes hear when you’re about to become a keto convert and start this popular and effective diet. Those who don’t know much about the keto diet will tell you that it will make you weak. This is especially the case for people who are athletes or are big into exercise. Fellow hardcore fitness enthusiasts will tell you that keto will decrease your performance. If you’ve ever seen a long-distance runner eat a big plate of spaghetti the night before a marathon, then you know what “carbo loading” is all about. And it’s the exact opposite of the keto diet.
Their reasoning? Carbs have been linked to endurance in athletes. So, they assume that, with a low-carb diet, you won’t be able to sustain high fitness. They claim that a keto diet will make you weaker or tire quicker–something an athlete definitely wouldn’t want.
Guess what: None of that is true (for the most part, anyway). Just like with most other aspects of life, you need to take some people’s advice with a proverbial grain of salt.
Ketogenic Diets Don’t Hurt Your Athletic Performance
The keto diet has been scientifically proven not to adversly affect athletic performance of top athletes once they’re used to the diet, according to Dr. Stephen D. Phinney. (1) They studied Inuit culture and found that tribes performed very well with this kind of diet, especially when their high-fat, low-carb diet consisted of 15% to 20% protein and adequate sodium and potassium.
Keep in mind what the ketogenic diet does to your body. Rather than using carbohydrate stores for energy (as is typical when carbo loading), you’re using fat stores instead. In the end, both are giving you energy, which is needed for high quality fitness. In fact, there are plenty of marathon runners that have great finishing times while on a ketogenic diet. (2)
However, the ketogenic diet can take some getting used to.
Take It Easy in the First Two Weeks
While a ketogenic diet is just as good as a carb-rich diet for athletes, changing between the two can take a bit of time for your body to get used to.
Though it isn’t always the case, keto dieters can have a rough time of it when they first start out. In the first two weeks, they may experience:
- Reduced concentration
- Lack of energy
- Stomach aches
This happens because your body needs to get used to the changes from using fat for fuel, rather than carbs. (3) These symptoms, commonly called “keto flu,” don’t happen to everyone. But, when they do, these symptoms can make extreme exercise a tough thing to handle. They typically last a few days up to two weeks.
Translation: It can be a bit of a bummer.
What does this mean for an athlete? It’s a good idea not to start a keto diet right before your marathon, CrossFit championship or bike race. Instead, start the diet when you have some time for your body to adjust.
And just know that, once ketosis kicks in and the symptoms go away, you’ll be feeling great and have high levels of energy that you can funnel into your fitness routine.
Not sure what kind of fitness you want to focus on? Check out our recent post, Using High Intensity Interval Training to Kick-start Ketosis.