Is it better to do aerobic exercise on an empty stomach or after a meal?

Is it better to do aerobic exercise on an empty stomach or after a meal? The answer is that there is no absolute advantage or disadvantage. The best choice is the one that completely matches your sports goals, physical foundation and current state.

When I was preparing for a half-marathon two years ago and brushing up my body fat at the same time, I climbed the stairs for 30 minutes at 6 a.m. every morning for two months in a row. At that time, my body fat dropped from 18% to 15%. The speed was much faster than before, which was all planned in the evening after dinner. But there was a price: I once worked overtime until 1 a.m. the day before and climbed the stairs the next day. When I climbed to the 12th floor, my eyesight went black. I squatted against the wall for 5 minutes before I recovered. I almost lost my grip on half of the energy gel in my pocket.

Why does it work better on an empty stomach at that time? In fact, the principle is not complicated. After about 8 hours of sleep, the glycogen reserves in the body are almost depleted. At this time, if you do moderate to low-intensity aerobics, your body will directly mobilize more fat for energy. The fat oxidation rate is 10% to 20% higher than if you do it after a meal. This conclusion is supported by exercise physiology research and is not just a boast by fitness bloggers. But the premise of this benefit is very strict: you don’t have underlying diseases such as hypoglycemia or diabetes, you have a stable exercise habit, and your exercise intensity is controlled at about 60% of your maximum heart rate. To put it bluntly, this means that you can still speak normally when you exercise, and you won’t be out of breath and unable to speak in full sentences. If you start running intervals on an empty stomach, your body will not only burn fat, but also tear down muscles for energy, which will destroy your basal metabolism and cause more harm than gain.

I took my mother to exercise last year. She heard from the aunt in the community that fasting exercise makes her lose weight quickly. When she got up in the morning, she followed Liu Genghong without eating. After only 10 minutes, her face turned pale and she broke out in a cold sweat. I quickly stuffed her with half a piece of whole wheat bread and waited for a long time before she recovered. This is the most obvious shortcoming of fasting aerobics: for people with poor basal metabolism and little exercise, as well as middle-aged and elderly people, and people with unstable blood sugar, the risks of fasting exercise far outweigh the benefits. It can range from dizziness and fatigue to direct fainting and falling. There is no need to take this risk.

As for the often-asked question of whether exercising after meals will cause gastroptosis, it actually depends entirely on what you ate and how long it took for you to exercise. Now that I finish taking out food at noon on workdays, I won’t immediately lie down at my workstation to sleep. Instead, I will walk slowly around the campus for 20 minutes. I won’t feel a stomach ache, and I rarely get sleepy in the afternoon. During last year’s physical examination, my postprandial blood sugar was much more stable than before when I lay down at my desk every day. Generally speaking, if you eat an ordinary simple meal, it is perfectly fine to do low-intensity aerobics every 40 minutes to an hour. If you eat a high-fat and high-sugar meal such as hot pot and barbecue, it is best to wait more than 2 hours before exercising. If you run and jump immediately after eating, it will indeed cause gastrointestinal discomfort.

If your goal is to gain muscle, and aerobic is only used to maintain cardiopulmonary function, then there is no need to do fasted aerobic. Just do 20 minutes of low-intensity aerobic after strength training. This can control body fat without worrying about losing muscle. If you are stuck in the fat loss plateau recently and your physical condition is good enough, doing fasted aerobics 2-3 days a week can really help you break through the plateau quickly. You don’t have to do it every day. If you do it too much, you will easily lose muscle.

Oh, by the way, there is actually debate in the academic circles about the "fat-burning efficiency" of fasted aerobics. Some studies say that even if you burn more fat on an empty stomach, the total consumption when extended to 24 hours is actually the same as aerobics after meals. So there is no need to deify fasted aerobics. There is no need to force yourself to exercise on an empty stomach just because of the possible fat-burning difference, making you feel anxious every time you think about exercise.

To put it bluntly, if you feel refreshed when you wake up in the morning, don’t feel hungry at all, and feel comfortable climbing stairs and walking, then exercise on an empty stomach.； If you wake up in the morning so hungry that your chest touches your back and you want to chew on everything, then eat a small banana or half a piece of bread before moving on. There is really no rigid standard. The most important thing about exercise is that you can persist for a long time, rather than worrying about the little details of efficiency. After all, if you can move three times a week without moving, it is much better than worrying about fasting or after eating for half a month, and not moving the last time, right?