Is it true that your body starts burning fat after exercising for 30 minutes? Aerobic vs anaerobic, which is more effective for exercise and weight loss?

When you look up these questions on the Internet, there will always be a key word "three primary energy supply systems". People who answer questions will often give a brief introduction to these systems, they are: Phosphatogen system, Anaerobic Glycolysis system and Aerobic Glycolysis system.

But what are they?

Phosphatogen system (immediate source): it mainly supplies energy for the exercise with high intensity and short time. This system is anaerobic, which means it does not use oxygen. The ATP-PC system uses a relatively small amount of ATP already stored in the muscle for this direct energy source. When the body's ATP consumption is exhausted in a matter of seconds, the breakdown of phosphocreatine (PC) forms an additional ATP, an energy compound found in muscle.

Anaerobic Glycolysis system (somewhat slow, uses carbohydrates)：it mainly supplies energy for middle-high intensity and short-term exercise. This system does not require oxygen, but uses the energy contained in glucose to form ATP. This pathway occurs within the cytoplasm and breaks glucose down into a simpler component called pyruvate. As an intermediate pathway between the phosphagen and aerobic system, anaerobic glycolysis can produce ATP quite rapidly for use during activities requiring large bursts of energy over somewhat longer periods of time (longer part time is 30 seconds to three minutes, or during endurance activities prior to steady state being achieved).

Aerobic Glycolysis system (slow, uses either carbohydrate or fat) : It mainly supplies energy for low intensity and long-term exercise. This pathway requires oxygen to produce ATP because carbohydrates and fats only burn in the presence of oxygen. This pathway occurs in the mitochondria of cells for activities that require sustained energy production. The aerobic glycolysis ATP is produced at a slower rate and is mainly used in the lower intensity activities of phosphorus and anaerobic systems for a longer period of time.

Human motion is a process from chemical energy to mechanical energy, which includes two parts: energy generation and energy utilization. Energy production involves the three major energy supply systems and three major energy substances of the human body, and other nutrients also affect the health of the human body's sports performance by affecting the metabolism of the three major energy substances. We must understand the energy system of human body, the energy materials consumed by each system, and the time required for energy recovery after training, in order to effectively implement the fat burning program, obtain better returns, and achieve fitness goals.