Physiological backlashes of extreme dieting: gastrointestinal disorders, decreased basal metabolic rate, and "revenge" weight rebound.

Most obesity is caused by a long-term excess of energy intake over energy expenditure, resulting in a positive energy balance in the body. The core logic of dieting for weight loss is to artificially create a negative energy balance by strictly controlling diet and reducing total calorie intake, thereby forcing weight loss. Typically, obese patients who adopt dieting methods restrict their daily total calorie intake to between 600 and 1200 kcal.

In the initial stages of a simple diet, weight loss can indeed be rapid due to minimal or no calorie intake, making the weight loss effect seem very significant. However, this apparent result comes at a huge physiological cost and is extremely unstable. Simple dieting not only disrupts gastrointestinal function but also triggers a series of serious nutritional deficiencies.

People who diet for extended periods often exhibit symptoms such as dry, dull skin, muscle weakness, significant hair loss, and sluggishness. Furthermore, due to insufficient nutrient supply, the body's immunity decreases dramatically, making them prone to various disorders such as gallstones, anorexia nervosa, or bulimia. In severe cases, it can even lead to electrolyte imbalances, acidosis, orthostatic hypotension, and menstrual irregularities.

Even more critically, our bodies are incredibly intelligent organisms with an innate capacity for self-regulation. When we go without food for extended periods or consume very little, our bodies mistakenly perceive a "famine" and activate a defense mechanism: actively lowering our basal metabolic rate to conserve energy. This regulation is designed to maintain and prolong life, causing fat loss to slow down even with minimal intake.

Once this extreme diet is interrupted and eating resumes, the body's cells, which have been in a state of "starvation" for a long time, exhibit an extremely strong ability to replenish nutrients and rapidly accumulate energy. This is the fundamental physiological reason for the rapid rebound in weight, even to the point of being heavier than before the diet.

Furthermore, simply starving yourself to lose weight not only depletes fat but also consumes a large amount of non-fat tissue (such as muscle and visceral tissue), which can cause irreversible damage to bodily functions. For example, a lack of fat intake can lead to a deficiency of essential fatty acids, causing not only rough, peeling skin but also stunted growth, infertility, and in severe cases, even death.

Therefore, extreme dieting is an extremely unhealthy method. A scientific weight loss plan advocates moderate and scientific calorie control under the guidance of a professional physician or nutritionist, ensuring a complete intake of various vitamins, minerals, and essential nutrients. More importantly, dieting must be combined with appropriate physical exercise. Exercise not only improves physical fitness but, more importantly, counteracts the decrease in metabolic rate caused by dieting, ensuring that the weight loss is genuine excess fat rather than valuable muscle tissue. Improving resting metabolic rate through exercise is the only effective way to consolidate weight loss results and prevent rebound.