Should you exercise on an empty stomach?



If you workout first thing in the morning, you probably do it before eating a full breakfast.

There’s been an ongoing debate about whether it’s necessary to fuel up before going for that run or hitting the gym. Many studies say fasting before a workout helps you burn fat, while others suggest there’s some risk involved.

Kelly Pritchett, a board certified specialist in sports dietetics and an assistant professor in nutrition and exercise science at Central Washington University, says that while it’s not strictly necessary, eating before exercise can help top up your glycogen, or stored carbohydrates, which is what fuels our workouts.

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“Going into the workout well fueled will allow you to work at a high intensity, which equates to a better quality workout,” says Pritchett.

If you don’t have enough glycogen, your body burns other energy sources like fat.

“If someone doesn’t eat they may fatigue quicker. Although controversial, the train low (in a glycogen depleted) state forces the body to rely more on fat as a fuel source.”

Although ‘burning fat’ as a fuel source sounds like something you want to achieve, it’s not a good thing at all - it it could also make you lose more muscle.


“If someone is going to train in a fasted state, I would suggest doing it only during the base phase of training and not during key workouts. You need fuel to increase lean tissue and to build muscle.”

Pritchett says pre-workout meals are also crucial for certain types of fitness.

“If you are performing an activity that requires a great deal of thinking or decision making, like mountain biking, then you may increase your risk of injury in a fasted state since the primary source of fuel for the brain is carbohydrates.”

In terms of pre-workout meals, Pritchett recommends something that’s “high carbohydrate, moderate protein and low in fat.”

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It also depends on the timing of your meal. Three to four hours before, Pritchett suggests consuming a larger meal like breakfast cereal and milk, oatmeal topped with banana and peanut butter or a sweet potato with cottage cheese. If you’re eating one to two hours before, stick with something less filling like a granola bar, yogurt or a smoothie.

Eating after exercise can be just as important. While it depends on how long you trained for, eating a meal afterwards can help you with your future visits to the gym. Pritchett says if someone is training twice a day or longer than 90 minutes, a post exercise meal becomes an important tool for recovery so you can perform well at the next session.

“Again, high carb with about 20 to 25 grams of protein will help replace muscle glycogen stores and help repair muscle tissue.”

If you’re adamant in getting the most out of your workouts, eating beforehand will help.

“Food is fuel! Your body is similar to a race car. In order to get the most of your workout you need to go in well fueled and provide it with the best gas.”

Do you exercise on an empty stomach? Let us know your thoughts by tweeting to @YahooStyleCA.