Who supplies energy first, fat or protein

In the process of energy metabolism in the human body, the sequence of energy supply from fat and protein depends on the intensity and duration of exercise. carbohydrates are usually prioritized for energy supply, followed by fat, and protein only participate in energy supply in cases of long-term hunger or extreme conditions. During the early stages of exercise or high-intensity exercise, the body primarily relies on the breakdown of stored glycogen into glucose to provide energy. At this time, carbohydrates are the primary energy source, and the energy supply ratio of fat and protein is relatively low. After moderate intensity continuous exercise for more than 20 minutes, the proportion of fat oxidation gradually increases and becomes the main source of energy. The fatty acids produced by fat breakdown undergo beta oxidation to generate a large amount of adenosine triphosphate, which is suitable for the energy requirements of long-term low-intensity activities. Proteins, as important components of tissues, are usually not the main energy source. But during prolonged hunger, glycogen depletion, or extreme energy deficiency, muscle protein is converted to glucose through gluconeogenesis. In this situation, protein energy supply may reach a small proportion of total energy consumption, but it can cause muscle loss. Under normal diet and exercise, the proportion of protein energy supply is usually very low, and a reasonable diet can avoid excessive consumption of protein. Maintaining a balanced diet can help optimize energy metabolism. It is recommended to consume an appropriate amount of carbohydrates as a basic energy source daily, combined with high-quality protein to maintain muscle health, while controlling the proportion of fat intake. Regular exercise can improve the efficiency of fat oxidation, and supplementing carbohydrates in moderation before exercise can reduce protein breakdown. Long term dieting or insufficient energy intake may lead to muscle loss, and extreme dietary patterns should be avoided.