Why You Should Exercise on an Empty Stomach

Jogger stretching before workout

You’ve probably heard this bit of conventional exercise wisdom: you have to pre-fuel so you don't run out of gas during your workout!

But is that always the best advice? Well, if your goal is to lose weight faster, build more muscle, and get in eat-your-heart-out shape for the next time you run into your ex, science says it might be better and even smarter for you to exercise on an empty stomach. Here's how it works: 

You'll improve your insulin sensitivity

Insulin is an important hormone in the weight-loss puzzle because it's a critical player in how your body metabolizes sugar. Eating too much sugar is bad for a lot of reasons, one of which is that it can make your body more resistant (or less sensitive) to insulin’s sugar metabolizing effects, which can lead to things like diabetes and weight gain down the line. 

This is where exercising on an empty stomach comes in: research shows it can actually help your body become more sensitive to insulin, thus making it easier to burn off the sugar you eat.

You'll boost your growth hormone production

The second effect of fasted exercise is that it boosts growth hormone, which plays a role in your metabolism and helps protect lean muscle. In fact, after a 24-hour fast, men and women experience a 2,000% and 1,300% increase in HGH production, respectively. If your name isn't Peyton Manning, that HGH boost will do wonders for you. 

All this is great, but the improved insulin sensitivity and growth hormone boost aren't quite as motivating when you're starving and have to go to the gym. Here are a few tips for a great workout that will get you results:

Female drinking glass of water

Hydrate well before your workout

Dehydration is a common cause of exercise fatigue, and nothing can make a fasted workout feel more like hell on Earth than not being properly hydrated. Sounds simple enough, but too many people forget this basic step. 

Break your fast with a high-protein meal

Any type of exercise is a form of stress on the body that causes variable degrees of muscle loss. You want to begin the recovery process after your workout by feeding your muscles key rebuilding nutrients, namely lean protein. 

Man sleeping peacefully in comfortable bed

Don't discount the power of sleep

Getting a good night’s sleep is an overlooked component of building muscle, but sleep has a significant positive effect on growth hormone. When you're using fasted training, make sure you get a good night's rest so your body is primed to achieve that lovely HGH boost.

So I should never eat before exercising?

Keep in mind that different people work out best under different circumstances, so it's totally up to you and what works best for you. That said, there's solid science touting the benefits of exercising on an empty stomach, and I know from personal and professional experience that fasted training is a simple and effective tool that helps many people lose weight and build muscle.

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Dr. Phoenyx Austin, M.D. is a sports medicine specialist and the creator of women’s nutritional supplements for healthy hair and body. Find Dr. Phoenyx on her website and YouTube channel where she shares her passion for all things fitness, natural beauty, and awesomely healthy living.