The double-edged sword of exercise for weight loss: the dangers and assessment of excessive exercise.

8.3 Exercise and Weight Loss

Exercise for weight loss primarily emphasizes regulating metabolic function, enhancing fat consumption, and promoting fat breakdown. During exercise, a large number of muscles are involved, and muscle activity requires a significant amount of energy. Exercise promotes fat metabolism and utilization. Excess blood sugar is consumed during exercise instead of being converted into fat, thus controlling weight. However, the amount of calories burned during exercise depends on the intensity and duration of the workout.

The body's normal energy expenditure mechanisms indicate that it primarily uses carbohydrates. Scientific studies have shown that the body needs to exercise continuously for over 45 minutes at 75% of its maximum oxygen consumption to burn fat. This method of weight loss is difficult for most people to maintain, and excessive exercise can cause physical injury. The most effective weight loss method is to control your diet to achieve a negative energy balance, low glycemic index, and high nutritional content.

8.3.1 The dangers of excessive exercise in obese individuals

Excessive exercise can increase the burden on various organs, reduce lifespan, and accelerate aging, because the exercise of obese people is not a normal exercise, but an excessive exercise relative to their own body.

Increased exercise leads to a corresponding increase in the body's need for oxygen, nutrients, and metabolic waste products. This necessitates the heart to increase its contraction force and frequency, thereby increasing the amount of blood pumped out. During intense exercise, the heart's output may not meet the body's oxygen requirements, resulting in an anaerobic metabolic state. Exercise does not primarily utilize fat for energy release; instead, it relies mainly on the breakdown of stored glycogen.

In an oxygen-deficient environment, fat not only cannot be utilized, but also produces incompletely oxidized acidic substances such as ketone bodies, reducing the body's exercise endurance. Low blood sugar is a major cause of hunger; after high-intensity exercise, blood sugar levels drop, often leading to increased appetite, which is detrimental to fat loss.

The greatest harm of excessive exercise is joint wear and tear. Long-term excessive exercise against gravity causes joints to wear down faster than normal. Once joints are damaged, they are difficult to repair, especially in middle-aged and elderly people whose organs have lower self-repair capabilities. The older one gets, the greater the degree of joint wear and degeneration. Therefore, moderate exercise is a very important concept. How much exercise is not excessive depends on one's current physical condition; the appropriate amount of exercise is when the body does not feel uncomfortable.

If you've experienced any of these symptoms after exercising: fat gain instead of loss, insomnia after exercise, mood swings, irritability, fatigue, lethargy, listlessness, a feeling of impending death, knee pain, cold symptoms, or runny nose, then you should consider whether you've overtrained.

How can I determine if I'm exercising too much?

Since it's clear that excessive exercise does more harm than good, it's crucial to monitor your exercise intensity during workouts to ensure you're not exceeding your limits. There's no fixed standard for judging whether exercise is excessive; it varies from person to person. However, if the following reactions occur, you should pay attention immediately:

①Feeling tired even with minimal exercise;

② Lack of enthusiasm for exercise, decreased appetite, or even nausea during exercise;

③ After the same amount of exercise, the body felt very weak, the recovery time was longer, and the effect was not ideal;

④ Exercise can actually worsen sleep quality, leading to frequent awakenings or even insomnia;

⑤ Feeling listless all day, with low work and exercise efficiency;

⑥ Decreased sense of balance, accompanied by reduced muscle elasticity;

⑦ A significant decrease in libido;

⑧ Both resting heart rate and exercise heart rate were significantly elevated;

⑨ You have recently experienced pain or sudden injury to your joints or other body parts.

If you experience any of the above symptoms after exercising for a period of time, you should be alert; if you experience two or more, you may be overexerting yourself and should reduce the amount of exercise and revise your exercise plan accordingly.

8.3.2 Exercise is also a double-edged sword

Water can carry a boat, but it can also capsize it. If we compare a healthy body to a boat, then exercise is the water that allows it to sail smoothly or capsize it instantly. Regular physical exercise is widely recognized as an effective way to improve physical fitness and prolong life, and the benefits of exercise are numerous: regular exercise can increase cardiorespiratory endurance and reduce the risk of cardiovascular disease; it can help improve body shape and control weight; it can delay aging, tighten skin, and increase bone density; it can eliminate tension and relieve stress, etc. However, even the best things should be done in moderation and according to their principles. Blindly engaging in excessive physical exercise beyond the body's capacity will inevitably have side effects on health and may even cause irreversible damage.

A survey conducted at the American College of Cardiology Scientific Sessions indicated that people who ran an average of more than 20 miles (approximately 32 kilometers) per week did not live as long as those who ran less than 20 miles per week. While numerous studies in recent years have shown that running can reduce the risk of cardiovascular disease, new research suggests that prolonged endurance exercise carries health risks. Studies indicate that excessive exercise can damage the cardiovascular system, especially during high-intensity exercise. When the blood supply to the coronary arteries cannot meet the heart's demands, it can cause myocardial ischemia, leading to heart failure and even sudden death. Furthermore, excessive exercise can cause autonomic nervous system dysfunction, increased sympathetic nerve excitability, and exercise-induced hypertension. Therefore, people without a regular exercise routine should increase their exercise levels, while avid exercisers and even those addicted to exercise need to moderate their activity levels.