The core of scientific weight loss: adjusting energy balance and ensuring nutritional balance.

Adjusting Energy Balance:

Losing weight requires controlling diet to maintain a negative energy balance, while maintaining weight requires adjusting diet to ensure energy balance.

When obese patients begin weight loss, they need to reduce excess weight. This requires dietary calorie intake to be lower than the body's actual calorie expenditure. Therefore, it is necessary to control the diet (e.g., provide a low-calorie diet) to create a negative energy balance, prompting the body to metabolize the excess calories until weight returns to a normal level. Then, the diet should be adjusted to achieve and maintain a balance between calorie intake and expenditure. The specific amount of calories supplied should be comprehensively considered based on the obese patient's specific situation. First, the patient's daily dietary calorie level before treatment should be considered; second, it should be determined whether obesity is in an ascending or stable phase; third, for children, their growth and development needs should be considered, and for the elderly, any existing complications should be noted; calorie control must be gradual, decreasing step by step to increase calorie expenditure. For teenagers who are still developing and consciously pursue a beautiful figure, the focus should be on strengthening daily physical exercise. They should absolutely avoid blindly controlling their diet to prevent anorexia nervosa. For pregnant women, to maintain a normal fetal position and reduce the risk of preeclampsia, the focus should be on reasonably controlling calorie intake, and excessive physical activity is not advisable.

Generally speaking, for obese adults, a steady weight loss of 0.5–1.0 kg per month is recommended, which means reducing daily calorie intake by 523–1046 kJ (125–250 kcal) compared to the normal intake. However, for moderately or severely obese adults, given their greater potential for obesity and their often increased appetite and craving for high-calorie foods, coupled with the restriction of physical activity due to obesity, which further reduces calorie expenditure, a vicious cycle is created, making it difficult to curb the trend of obesity. To break this pattern, calorie intake must be strictly limited. A weight loss of 0.5–1.0 kg per week and a daily calorie reduction of 2.30–4.60 MJ (550–1100 kcal) are recommended, and this should be strictly controlled.

Ensuring nutritional balance: Dietary choices should not only consider calorie balance but also the balance of various nutrients.

Ensuring nutritional balance means maintaining a balanced ratio of the three major nutrients (protein, fat, and carbohydrates), fiber, minerals, and vitamins to meet the body's physiological needs.