However, long-term aerobic exercise will consume muscles, leading to a decline in metabolic rate, which is not conducive to weight loss, so it is necessary to reduce fat first and then gain muscle. Aerobic exercise consumes fat and energy, but it will make people's appetite very good. However, due to the decrease of muscle content, metabolism also decreases. If you stop exercising, it is easier to accumulate fat and cause your body to rebound. A large number of studies show that if you do aerobic exercise for two hours, 90% of leucine in your body will be consumed, and leucine can promote muscle growth. Excessive exercise can easily lead to muscle strain, so you need to find a balance. There is an upper limit to aerobic exercise. Once you exceed this balance point, your body fat will be consumed and your muscles will be consumed. If you are a big fat man, start with aerobic exercise, lose fat first and then gain muscle. If you are a muscular man with thick thighs, try to do aerobic exercise. It's also good to lose fat first and then muscle.