What are the side effects of weight loss on the body?

Generally, although weight loss can help improve health, it may also bring many side effects, commonly including decreased metabolic rate, muscle loss, malnutrition, endocrine disorders, and mental health issues. A detailed analysis is as follows:

1. Decreased metabolic rate: Excessive dieting or adopting extreme weight-loss methods significantly reduces calorie intake. To sustain survival, the body activates protective mechanisms, lowering the basal metabolic rate and decreasing energy expenditure. Long-term effects like this can easily lead to weight rebound once normal eating resumes, as energy consumption is low while intake is high—sometimes even resulting in greater weight gain than before dieting.

2. Muscle loss: During rapid weight loss, without a reasonable exercise plan, the body may break down muscle for energy while burning fat. Reduced muscle mass further lowers the body's basal metabolic rate, affects strength, endurance, and athletic performance, weakens the body's supportive and protective functions, and increases the risk of injury.

3. Malnutrition: Some dieters strictly limit food types and intake, reducing consumption of staple foods, meats, and fats, which may lead to insufficient intake of nutrients such as protein, carbohydrates, fats, vitamins, and minerals. This can trigger a series of health problems including anemia, reduced immunity, osteoporosis, and dry skin.

4. Endocrine disorders: Hormone levels in the body can be affected during weight loss. Excessive dieting or high stress may disrupt the normal function of the hypothalamic-pituitary-gonadal axis, causing menstrual cycle irregularities, reduced menstrual flow, or even amenorrhea in women. Men may experience hormonal imbalances that affect reproductive health and sexual function.

5. Mental health problems: During weight loss, if the weight loss does not meet expectations or if others give negative feedback about the results, individuals may develop negative emotions such as anxiety, depression, and inferiority. Overemphasis on weight and body changes may even lead to eating disorders such as anorexia nervosa or bulimia, seriously harming physical and mental health.

When losing weight, one should choose scientifically sound methods, develop a balanced diet plan to ensure comprehensive nutrient intake, combine moderate aerobic exercise with strength training to prevent muscle loss, and maintain a healthy mindset without being overly demanding about speed or results. Only in this way can weight-loss goals be achieved while maintaining good health.