How long does it take for aerobic exercise to start burning fat?

In fact, from the first minute you start doing low- to medium-intensity aerobic exercise, fat is already involved in providing energy. The online saying that "you must exercise for more than 30 minutes to burn fat" is simply a misunderstanding.

A girl I took care of two years ago who was in the process of losing weight was determined to run for 40 minutes continuously every night at first. Sometimes she worked overtime late and didn't have enough time, so she simply stopped moving that day. She always felt that moving for 20 minutes was a waste of time. Later, I explained this misunderstanding to her, and she changed to walking briskly for 20 minutes each time to and from get off work, and took another 10 minutes to climb stairs at noon. She did not have to squeeze in a long time in the gym. She also steadily lost 10 pounds in three months, and her body fat rate dropped by 3 points.

Speaking of this, someone must ask, why has everyone been talking about the 30-minute threshold for so many years? If you compare the energy supply system to two co-workers working together, you will understand: at the beginning of exercise, the glycogen stored in the muscles and blood is impatient. The more effort you put in, the faster you work. The energy supply ratio of fat is indeed low, only about 20%-30%. ； When you maintain a medium-low intensity—that is, an intensity where you can speak normally but cannot sing coherently—for 20 to 30 minutes, glycogen will be depleted and your energy supply will be almost exhausted. Only then will the energy supply ratio of fat, a chronic condition, climb to a peak of more than 50%. At this time, if you exercise for the same 10 minutes, the amount of fat consumed will indeed be higher than in the first 10 minutes. Many people mistake this point of "increased energy supply ratio" for the point of "fat begins to participate", and it is said that it only takes 30 minutes to burn fat.

Of course, there are also different practical experiences in the circle: if you do strength training for ten minutes before exercising to use up part of your glycogen reserves, then as soon as you start aerobic exercise, the energy supply ratio of fat can directly rush to more than 40%, without waiting for half an hour.； There are even studies in the field of exercise physiology in recent years that show that intermittent high-intensity aerobic (HIIT) has a stronger fat consumption effect. Even if it is only practiced for 15 minutes at a time, the resting fat consumption in the subsequent 24 hours is higher than that of steady-state aerobics for 40 consecutive minutes. This is why many office workers who have no time now prefer short-term and efficient exercise.

That’s not to say that long-term aerobics is meaningless. If you have enough time and good joint condition, if you do mid- to low-intensity aerobics continuously for about 40 minutes, the overall total fat consumption will indeed be higher. But there is really no need to hold on to the time card. It is purely unnecessary internal consumption to worry about "whether the exercise is in vain before 30 minutes." If you really want to lose fat, moving is better than lying down. If you can stand, don't sit. If you can walk two more steps, don't wait for the elevator. Even if you do three 10-minute activities every day, you will see real changes in the long run.