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When to Work Out While Intermittent Fasting, Expert Reveals

Gear up for that weight loss journey of yours!

If you're trying to lose weight, you may consider doing intermittent fasting along with your fitness regimen. But before you do, we chatted with an expert—Dr. Mike Bohl, the Director of Medical Content & Education at Ro and a certified personal trainer—who reveals everything you need to know about it, including when to work out while intermittent fasting. Keep reading to learn the details, and get excited for that weight loss journey of yours!

What is intermittent fasting?

fitness woman pouring green smoothie

First off, what is intermittent fasting? Johns Hopkins Medicine describes it as alternating between a regular eating schedule and fasting. When you're intermittent fasting, you can only have meals during a particular timeframe. Many individuals do it as a means to maintain a healthy weight or lose weight.

Related: The #1 Strength Workout To Regain Muscle Mass as You Age, Trainer Says

When should you work out while intermittent fasting?

mature woman running on the beach

There are a variety of different intermittent fasting schedules out there, so the time period when you enjoy meals versus work out could depend on what personal schedule you're sticking with. "If you work out during your eating period (or shortly before or shortly after), you can follow the usual recommendation—have carbohydrates before the workout (skip this if you're working out shortly before your eating period)) and carbohydrates and proteins after (skip this if you're working out shortly after your eating period)," Dr. Bohl says.

Related: What Happens to Your Body When You Work Out 7 Days a Week

You can work out while intermittent fasting, but beware of a few things that could happen.

tired woman during workout at gym, demonstrating when to work out while intermittent fasting

While Dr. Bohl reveals it's certainly doable to work out while intermittent fasting, be mindful of a few things. You may have less energy and find that performing exercise is more difficult than usual. Subpar performance can result in a subpar workout, and nobody wants that. In addition, if your body's not getting energy from food, it might end up breaking down proteins to use as fuel. As a result, you could lose some of your muscle mass.

Above all, it's necessary to stay mindful of how you're feeling. "Working out lowers your blood sugar, and if you haven't eaten any food before your workout, your blood sugar may get too low," Dr. Bohl says. This could make you dizzy and lightheaded, and even cause you to faint. If you're not feeling yourself while exercising, Dr. Bohl encourages you to take a breather or stop working out and eat something to bring your blood sugar back to a normal level.

Lastly, make sure you're drinking enough H2O during workouts—and not just for rehydration. Dr. Bohl recommends opting for a beverage that contains electrolytes as well to give your body back what it loses when sweating.

What exercises should you choose when intermittent fasting for weight loss?

swimmer swimming laps, demonstrating when to work out while intermittent fasting

You're likely wondering what exercises are best paired with your intermittent fasting routine, and which ones you should avoid. Dr. Bohl reveals that when intermittent fasting for weight loss, opt for cardio and other low-intensity activities. "These are exercises that primarily rely on burning fat for energy, so they can help with your goals," he reveals. However, be careful when lifting weights while fasting. If you don't "replenish your protein stores" after performing a weight lifting session, your body can break down proteins for fuel, and you can lose muscle mass.

Alexa Mellardo
Alexa is the Mind + Body Deputy Editor of Eat This, Not That!, overseeing the M+B channel and delivering compelling fitness, wellness, and self-care topics to readers. Read more about Alexa