The truth about exercise and calorie expenditure: Why is intense exercise often ineffective for weight loss?

The energy expenditure from exercise doesn't account for a large portion of our daily energy consumption; on the contrary, the energy consumed by exercise only accounts for a small fraction of a person's total daily energy expenditure. This fact is often overlooked.

Humans obtain energy primarily through food intake, but energy expenditure is not so simple. Energy expenditure is mainly divided into three parts: basal metabolism, food digestion, and daily activities. The largest portion of energy expenditure in the body comes from basal metabolism, accounting for 60% to 80% of total energy expenditure; energy expenditure from food digestion accounts for 10%; and the energy consumed by daily activities accounts for only 10% to 30% of total energy expenditure. Exercise is only a part of daily activity expenditure, and thus only a small fraction of total energy expenditure.

In other words, even if you exercise strenuously for half a day, the actual increase in energy expenditure may be far less than you imagine.

Moreover, as the amount of exercise increases, the body's energy utilization efficiency also increases. This means that the body becomes smarter at conserving energy. For example, when you exercise your muscles in the gym, you gradually feel less tired, so your trainer will gradually increase the weight. This is because the body has become accustomed to your exercise level and automatically reduces energy consumption.

Furthermore, compensatory behavior doesn't only occur in eating more; excessive exercise can also make people lazier, thereby reducing the energy expenditure of daily activities. That is to say, although exercise increases energy consumption, compensatory behavior reduces the energy consumption of other daily activities such as climbing stairs, doing housework, and walking. The total energy consumption will still tend to stabilize.

Therefore, simply extending exercise time and increasing exercise intensity will not help you increase much additional energy expenditure; the body will try to control energy expenditure levels in various ways.