Scientific weight loss: How to balance the intake ratio of the three major nutrients?

Maintaining a balance of the three major nutrients—fat, carbohydrates, and protein—is crucial. Because fat is high in calories, dietary fat intake can easily lead to excess energy intake. Especially when carbohydrate intake is restricted, excessive fat intake can cause ketosis. Therefore, when restricting dietary energy intake, fat intake must also be limited. Furthermore, dietary fat has a strong satiating effect, which can reduce appetite. To ensure a low-calorie diet with strong satiety, dietary fat restriction should not be too strict. Therefore, for obese individuals, dietary fat intake should ideally account for 25% to 30% of total dietary energy; any excessively high or low fat intake is undesirable. As for dietary cholesterol, the recommended intake remains the same as normal, generally less than 300mg per day.

Carbohydrates are high in calories, low in satiety, and can increase appetite, making them a target for restriction in weight-loss diets. However, excessive restriction of carbohydrate intake should also be avoided. Various ketogenic, high-fat, low-carbohydrate diets have been popular abroad. While obese individuals may experience significant weight loss initially with these low-carbohydrate diets, this is merely an illusion caused by the excessive water and salt excretion in urine due to early ketosis. This not only fails to achieve the intended weight loss but also leads to hyperlipidemia and arteriosclerosis. Furthermore, excessive loss of water and electrolytes can cause orthostatic hypotension, fatigue, muscle weakness, and arrhythmia. The uric acid retention caused by ketosis and muscle tissue loss can lead to hyperuricemia, gout, osteoporosis, or kidney stones. In addition, severe disruption of the entire metabolic internal environment can damage the kidneys and brain, harming the entire body, especially further impairing renal compensatory function in patients with kidney disease, and even leading to death. This must be taken seriously. Generally, carbohydrate intake (in calories) should not be less than 30% of total dietary calories.

While weight-loss diets often increase the proportion of protein, excessive protein intake should be avoided. Obesity is the result of excessive calorie intake. Therefore, any excess calorie intake, regardless of the source of the food, can lead to obesity, and dietary protein is no exception. Furthermore, under strict restriction of dietary calorie intake, excessive protein intake can cause irreversible damage to liver and kidney function. This dictates that protein intake should not be too high even in a low-energy diet. Therefore, for moderately to severely obese individuals following a low-energy diet, dietary protein intake should be controlled to 20%–30% of total dietary energy, or 50–75g of protein per 4.18 MJ (1000 kcal). High-biological-value proteins should be selected, such as milk, fish, chicken, egg whites, and lean meat.