A popular New Year’s resolution is to exercise more. Whether you’re training for a marathon or looking to get healthy, how you prepare for the gym is key. One decision you’ll have to make is whether you eat before your workout.
Exercising on an empty stomach is commonly thought to help burn fat. The logic is that people use fat and sugar for energy, so by not having anything in your stomach, you will burn off stored fat reserves in the body. However, the science to support this exercise “hack” is inconclusive. While working out on an empty stomach is not necessarily dangerous, depending on your fitness goals, it may be less than ideal.
“The answer is yes and no depending on your goals and capabilities,” says Alexander Rothstein, coordinator and instructor for the exercise science program at the New York Institute of Technology.
Exercising to burn fat
The research looking into the pros and cons of fast-and-burn workouts is limited. For some people who exercise on an empty stomach in the morning, higher rates of fat oxidation have been observed than in people who ate a meal containing carbohydrates 0.5-three hours earlier; a single session of aerobic exercise on an empty stomach can increase the use of reserved fat as a fuel source. In a 2022 study, fasting before evening exercise showed similar effects–it also impaired athletic performance.
One issue is that the benefits of fasting are short-term. While individuals do burn a percentage of reserved fat when fasting before exercising, Rothstein says there’s usually less total fat burned over time. That’s because the intensity needed to sustain a high-impact workout is more than the body can handle when it’s running on empty. For example, the 2022 study also found that fasting participants had a harder time maintaining the workout: When cycling as much as possible in 15 minutes (measured in kilojoules), participants that fasted for seven hours before the…
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