There are a lot of people who like to work out on an empty stomach. They all have their own reasons for doing it. Some people like getting up, putting on their shoes, and heading out for a run before doing anything else. Others believe that it benefits them in one way or another. I don’t. When it comes to my workouts, I can say that they’ve only suffered if I’m running on empty. The same can be said about the majority of the guys I’ve trained.
Why Some People Believe It’s a Good Idea to Work Out on an Empty Stomach
A lot of people think that if they work out on an empty stomach, they’ll burn more fat. After all, they haven’t had any food, so the fuel has to come from somewhere. It sounds like it makes sense that the body will then be forced to burn that stored fat for fuel. It sounds like it’s a great way to increase metabolism.
The body has several mechanisms in place to make sure your brain and your muscles always have enough blood glucose for fuel, even when in a fasting state. If you’re fasting and you exercise, once your blood sugar stores from food are used up, the body will turn to stored fat, converting it to glucose. That said, it will also steal protein from your muscles to convert that into sugar for fuel, too. While this may sound like being sugar starved can help you to speed up your fat burning, deciding to work out on an empty stomach is more complicated than that.
Yes, There Are Some Potential Benefits
Research conducted on healthy young men has shown that cardio workouts while fasting will raise the use of stored fat as fuel. This is believed to be a response to low insulin levels that result from the body’s fasting mode.
A second study on healthy young men took a step further and measured metabolic changes from choosing to work out on an empty stomach. They found that insulin is used more efficiently, meaning that it could help to reduce diabetes risk when done carefully and properly.
There Are Drawbacks, Too
All this makes it sound like it’s a great idea to work out on an empty stomach, right? Especially if you’re trying to lose weight (like I am right now. Check out my last blog post about my lockdown weight gain), this has appeal.
Unfortunately, the benefits for weight loss haven’t been shown in research like the potential benefits for potential diabetes risk reduction. Research cited by Harvard Medical showed that any research indicating that there are weight reduction benefits are few and far between. The largest study their researchers could find in favor of exercising while fasting was of 19 Muslim men during Ramadan, when fasting occurs during daylight hours for a month. Those who exercised were found to have lost slightly more weight and body fat than those who didn’t.
Why I Don’t Work Out on an Empty Stomach
The reason I don’t work out on an empty stomach goes further than what the research says. My own experience with my workouts and those of my clients shows that trying to do something physical on an empty tank gives me the following important disadvantages:
- Bad mood – I start hangry and get worse from there.
- Bad form – I’m far more likely to be sloppy about my form, meaning that I’m not getting the full benefits of the exercise, and I increase my risk of injury.
- Bad performance – I don’t have nearly the energy during a workout fueled by food as I do when I’m fueled by my own body fat and muscle. If I don’t perform as well because I’m dragging, I’m not going to get the results I want as quickly as I would otherwise.
- Bad food choices – Once I do start eating, I’m far more likely to make bad food choices. There is no way I’m going to want something reasonable to eat after a huge sweat session while fasting. At that point, I want something greasy, and I want a lot of it. So much for any progress I made that day…or the two days before it.