Why You Shouldn’t Train on an Empty Stomach
If you’ve ever tried going to the gym after a heavy meal, you probably know it’s not good, and you probably would have just skipped a pre-workout snack. But that doesn’t mean you should exercise on an empty stomach. This is why you are probably better off refueling before heading out for a run or doing some super sets at the gym.
The science
Let’s say it’s time for daily workouts . Do you have something to eat first? Or are you putting it off until you finish your regular regimen? Proponents of exercising while fasting or when hungry suggest that this way you can speed up your weight loss. One study published in the British Journal of Nutrition found that participants who exercised on an empty stomach burned nearly 20 percent more fat than those who ate before. Another study published in the International Journal of Sports Nutrition and Exercise Metabolism showed similar results, suggesting that fasting aerobic training reduced the percentage of body fat in addition to body weight compared to feeding training.
Why is excess fat burned? According to sports nutritionist Kelly Pritchett, M.D. , your body is switching fuel sources . In order to perform intense physical activities, such as long distance running or weight lifting, your body must burn glycogen or stored carbohydrates. If your body is running out of glycogen stores – as if it were in a hungry, hungry state – it needs to use something else to keep you going. In this case, it is the excess fat you have accumulated.
But there is a catch – well, some of them. First, your body doesn’t like to go hungry, and it likes to have fat stores. When you burn fat quickly, your body begins to regulate its metabolism to compensate for this loss. Basically, it goes into a kind of survival mode and starts burning fewer calories, Pritchett says. By burning that amount of fat, your body thinks it needs to store more of it the next time you eat, which completely neutralizes these fat burning benefits. And as another study published in the American Journal of Clinical Nutrition has shown , prolonged periods of fasting can lead to a decrease in resting metabolic rate. So in such a scenario, there is no real benefit to not eating.
According to one study published in the journal Appetite, pre-exercise can suppress appetite more than fasting exercise. In general, the participants consumed the same amount of energy per day, but those who ate before training were reluctant to eat more later. Given the fact that weight loss depends a lot on how you eat and not what you do , this can be an important weight loss factor for those involved in sports.
What does it do to your muscles
Under certain circumstances, exercising on an empty stomach can lead to the loss of some muscle in addition to fat . If your body is burning fuel glycogen stores, it can also get energy by breaking down muscle proteins in addition to these fats. Intense training always destroys muscles, so they can get stronger through protein synthesis, but if you do this during fasting, the muscles build up faster, making it difficult to recover the lost mass.
However, this only happens when you increase the intensity of your workout over your normal daily routine. If, say, you do a normal workout in the morning, your muscles are likely to still have enough glycogen stores from your previous meal. And according to one study from the Journal of Applied Physiology , fasting does not increase or decrease your physical performance or exertion during typical submaximal exercise. Basically, regardless of whether you are exercising with hunger or not, you can do your normal activities at normal intensity without worrying about losing muscle mass.
Not the best workout
However, this can lead to another problem. While you could do the workout on an empty stomach, you won’t have the energy to push yourself harder , and therefore it is unlikely that you will be able to recover at the same rate if you ate in the first place. A separate study published in the Journal of Sports Science and Medicine suggests that fasting training is significantly inferior to feeding training when it comes to maximizing exercise or reaching new personal bests. The jerk is what leads to increased muscle mass and reduced running time, so you need to do this as often as possible. If all said and done, eating a pre-workout meal can ultimately improve your metabolism.
In short, yes, you can work out on an empty stomach and live a normal life. Some people prefer this because they feel lighter, more alert, and more alert. But beyond personal preference, there aren’t many benefits. It is best to eat a carbohydrate-rich meal about an hour before your workout , and then eat a protein- rich and light-carb meal . In addition, refusal to eat leads to a bad mood . It is best to end your workouts feeling happy and refreshed rather than unhappy and ready to kill for food.
This story was originally published in 2017 and updated on October 21, 2020.