Working Out In a Fasted State

By: Ken Dominique

I’ve been asked about the potential benefits of intermittent fasting and fasted cardio. While more experienced athletes may need to fuel their workout to keep the intensity higher, there may be athletes whose goals are to lose weight that could benefit from doing a workout after not having eaten in 12, 18, or 24 hours prior to the workout. So, is working out in a fasted state really all it adds up to be? 

This is a great question, and it makes sense! If you’re trying to lose weight, you need to burn more calories than you take in through your diet (calories out need to be more than calories in). Your body uses stored carbohydrates (glucose) as energy, and when that glucose storage is depleted, your body looks for alternative sources of energy. This is the basis of the ketogenic diet, which has become very popular in the last few years. This is where you eat a VERY limited number of carbohydrates, so your body has no stored glucose and chooses instead to burn stored fat as energy. 

While there are plenty of benefits to fasting, is it right for everyone? 

The short answer is, no.

If the goal is weight loss, there are plenty of ways to lose weight and body fat by eating real food. Remember, your body NEEDS food. It’s literally what you use for fuel. When you deplete your body of calories before a workout, you could become hyperglycemic and pass out, you could burn muscle instead of fat, and you probably won’t have a good workout anyway because you’ll be severely lacking energy! This can lead to muscle loss, a lackluster workout, or a visit from the paramedics. 

Your best bet is to eat something light before your workout, like a small piece of fruit or some greek yogurt. Personally, I always eat a half of a banana before the workout, and the other half afterwards. 

If fasted workouts are something that you’re going to try, let me know first. I’ll give you a specific plan that you can execute safely to see if it’s something that you can do sustainably. For 99% of people, fuel your workout! You will find that you perform better, run faster, lift more weight, and have more stamina during a tough WOD! And what happens when you lift more weight? You get stronger! What happens when you take fewer breaks during an AMRAP? You burn more calories! All of these things are what actually gets us closer to our goals.