The Benefits of Exercising on an Empty Stomach

To eat pre-workout or not to eat pre-workout? This is a hotly debated question in the fitness world and has been for some time. We live in an age when every new fitness and diet regime swears it will be the one that helps you lose those last few pounds and give you superhero abs. So, needless to say, there are very different schools of thought when it comes to not eating before you sweat. Instead of debating on opinion, let’s look at the science behind not eating before a workout.


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How Your Body Burns Fat

Our bodies are optimized for survival. They want to take the shortest route from A to B and burn calories in the most economical way possible. Which means that when you exercise, your body will burn through carbohydrate stores before it starts to burn through fat. Carbohydrates are a source of fast energy that require less effort for your body to process than fats and proteins. Which makes sense; you are more likely to experience hunger sooner after eating carbohydrates than if you ate more filling proteins or fats. So in order for your body to burn fat, you need to burn off carbs first.

The Results are Coming In

The Journal of Physiology (Impact Factor 4.5) published a 2010 study that looked at the fat-burning effects of eating before and after a workout in a group of healthy, active young men. The results showed that the group that exercised before eating breakfast burned fat more efficiently. They did not gain weight—despite the high-fat diet they were fed—and did not develop a resistance to insulin. The British Journal of Nutrition (Impact Factor 3.3) published 2013 study that showed, “Healthy men who ran on the treadmill for 60 minutes at a moderate intensity before eating breakfast burned 20-percent more body fat afterward than when they ran the same distance two hours after eating a morning meal.” So is it safe to say that not eating before a workout is the best way to burn fat?

But more Research is Needed

While these studies demonstrated that there is a correlation between not eating before a workout and fat-burning, there is still much more research that needs to be done. The studies mentioned used only a small group of young men who were exercising in the morning before breakfast. The studies also focused solely on aerobic/cardio activities and not strength building exercises so there may be different effects in the case of not eating before weight training. Everybody is different and some people may experience a greater feeling of muscle fatigue if they don’t eat before they train.

My Personal Experience

I used to eat big breakfasts for years, despite there being no scientific evidence to back up the myth that breakfast is the most important meal of the day. Then, two years ago, I started intermittent fasting—8 hours of eating followed by 16 hours of fasting each day—which meant I started having breakfast later so I could have dinner at a later time. There was a bit of an adjustment period when I first started but after a while, my stomach shrank and I no longer felt the need to eat first thing in the morning. I also got over my fear of being hungry, something I used to be preemptively worried about. I did notice a drop in strength when I worked out on an empty stomach and science supports eating a light snack 30 minutes before training if you are trying to bulk. All in all, I have experienced an increase in energy and mental clarity and will continue to skip breakfast before I work out.

The best way to figure out if your body will benefit from not eating before a workout is to try it out. To make the transition easier, eat protein before going to bed so you don’t wake up hungry. If you are new to not eating pre-workout, you may find your body needs some time to adjust to your new routine. If, however, you find you need that pre-workout boost, have a small snack before you get moving. The key is to keep it small—such as half a banana—so that your body can get to burning fat faster. You can have a proper breakfast once you’ve had a good sweat. Not to worry about overeating it either; the men in the 2013 study who ran on an empty stomach didn’t consume extra calories at breakfast time, and my own experience is consistent