When you exercise in a fasted state — after a night's sleep and before you eat breakfast — then you do actually use more fat as a fuel source during exercise. But research from my team has shown that performing exercise in a fasted or fed state does not have any meaningful impact on body fat in the medium to long term.
No, running on an empty stomach at a given intensity burns the same amount of fat as being full at the same intensity. Some people think running on an empty stomach in the morning is the first thing they do, but this has more to do with the amount of exercise they do and the food they eat.
In general, it's recommended to eat before running. This gives your body the fuel it needs to exercise safely and efficiently. If you prefer to run on an empty stomach, stick to light to moderate running. The exception is if you're running a long distance or doing a high-intensity run.
While the body does use more fat when running in a fasted state this doesn't automatically equate to long term fat loss. Overall fat loss and body composition changes are dependent upon total daily calorie intake and energy balance over several days and weeks.
In general, it's recommended to eat before running. This gives your body the fuel it needs to exercise safely and efficiently. If you prefer to run on an empty stomach, stick to light to moderate running. The exception is if you're running a long distance or doing a high-intensity run.
According to a 2016 study published in the Journal of Nutrition and Metabolism, participating in a morning run after an overnight fast can increase fat oxidation during exercise and help you to decrease food intake over the 24 hours following exercise.
For example, a systematic review and meta-analysis published in 2016 in the British Journal of Nutrition states that an aerobic workout performed in a fasted state leads to greater fat oxidation, compared to a cardio workout done after eating.
So, running on an empty stomach helps our muscles use fat for fuel. This habit is great for burning more fat. By exercising without blood sugar, our body learns to use stored fat. This allows us to run longer and perform better, thanks to the energy from fat.
When you exercise in a fasted state — after a night's sleep and before you eat breakfast — then you do actually use more fat as a fuel source during exercise. But research from my team has shown that performing exercise in a fasted or fed state does not have any meaningful impact on body fat in the medium to long term.
Running on an empty stomach forces the body to tap into its fat stores for energy. When glycogen levels are low, the body resorts to burning fat as fuel. This can be advantageous for runners aiming to improve their body composition or enhance their fat-burning capabilities.
Another possible explanation is that exercising in the morning, specifically before eating, may also help the body burn fat. Since people are fasting when they are asleep, exercising before eating breakfast can help the body burn fat instead of carbohydrates, Ma said.
Flush Out Toxins
Toxins from pollution, UV exposure, smoking, sugars, and other factors can lead to skin inflammation, acne, early signs of aging, and more. Increased blood flow and lymphatic drainage during exercise helps to remove these toxins from the body to prevent further skin damage.
That plan is called the 30-30-30 rule. It's a simple but catchy idea that encourages you to eat 30 grams of protein within 30 minutes of waking up and then get 30 minutes of low-intensity exercise. The 30-30-30 rule now has millions of followers on TikTok.
Many folks can do moderate runs lasting less than an hour on an empty stomach with no problem. (Though you certainly can eat beforehand if you want to.) But if you're going longer or are doing something intense like intervals, hills, or speedwork, it's a good idea to get something in your stomach, says Scott.
Despite its popularity, fasted cardio has not been proven to help burn more calories or fat. But some people may prefer the approach for a variety of reasons. For example, if exercising in the morning before breakfast works better for your schedule and doesn't cause discomfort, you might make a habit of it.
But long runs alone aren't going to help you shed that belly fat. You also need to make dietary and lifestyle changes to shift those problem areas. Even if you're a regular runner who is watchful of what you eat, it's still possible to have belly fat that you just can't shift. In many cases, this can be down to diet.
Running can burn up to 671 calories in 30 minutes if the right conditions are met. Aerobic cardiovascular exercises, like running, have many physical and mental advantages. One of them is weight control. There's scientific evidence that less than three hours of cardio a week can help you maintain your weight.
Jensen says a person who runs but also eats a poor diet “could indeed keep their paunch” if their genes predispose them to carry excess fat in their midsection, and Church agrees. “In general, if you eat poorly, you tend to put weight on in your belly,” he says. (Ditto if you drink a lot of alcohol, he adds.)
Fasted running might not be the best approach for prolonged or high-intensity runs. Research suggests that eating before exercising can enhance performance over an extended period. So, if you're planning a run longer than 60 minutes or an intense interval session, you might want to fuel up beforehand.
It depends on the distance, your goals, the type of workout you want to do, and your preferences. It's generally recommended to eat before you run, especially if you're going to run for more than 45-60 minutes or looking to do a challenging workout. There's no need to eat immediately before your run, however.
If you want to improve or maintain your cardiovascular fitness, then running on a treadmill is fine. However, if you're training for a race or want to see greater benefits in terms of muscle tone, then running outside is the better fit for you.
Exercising during a fasting state increases lipolysis in adipose tissue while also stimulating peripheral fat oxidation, resulting in increased fat utilization and weight loss.
When you first wake up, you're a little dehydrated from your night of sleep, so it's a good idea to drink some water before a morning run. But you don't have to drink a ton—you don't want it jostling around in your stomach, after all. Even a few sips can help fight off fatigue during and after your run, Stefanski says.
While it is true that faster running burns calories at a faster pace, slow burns more calories in total.