Epidemiology and harm of obesity
As global productivity levels increase, the sources and types of foods are greatly improved, and the prevalence of overweight and obesity continues to grow globally. The current obesity status in China is also not optimistic. The 1980-2015 Global Obesity Survey shows In terms of the number of obese people, there were about 107.7 million children and 603.7 million adults obese globally in 2015; the countries with the largest number of adult obese people are China and the United States, and the countries with the largest number of children with obesity are China and India.
Obesity can lead to a variety of complications. A large number of epidemiological studies have shown that high BMI is a risk factor for a variety of chronic diseases, including cardiovascular disease, diabetes, chronic kidney disease and a variety of cancers.
Diagnosis of obesity
The 2016 AACE Obesity Guide believes that the current international diagnostic criteria for only overweight or obesity is not perfect. BMI is not the only standard for anthropometry, and waist circumference should also be used as a screening indicator, especially in BMI.< 35kg/m2的人群. 该指南广泛收集包括IDF, WHO在内的7个肥胖相关机构的数据, 对12个不同种族的腹部肥胖切点进行汇总, 并特别指出东南亚, 南亚, 东亚地区宜以男性腰围≥85cm, 女性腰围≥74-80cm作为腹型肥胖的切点.
Chinese obesity diagnosis cut-off point
Obese diet intervention
The method of weight loss is nothing more than changing lifestyles, using weight-loss drugs and using metabolic surgery. Among them, changing the original bad lifestyle is a fundamental measure. Lifestyle changes mainly include medical nutrition therapy, changes in exercise and behavioral modes, etc. In the process, strict restriction of the intake of energy substances (heat card) can significantly reduce weight, but it is often difficult to last. To this end, people continue to explore different dietary types, hoping to meet the patient's demand for food, and increase the compliance of nutrition therapy. , thus maintaining the 'ideal' weight for a long time.
Three main weight loss diet strategies
Strategies for weight loss diets include: low-calorie diets (energy-limited diets, intermittent fasting, fasting simulated diets), low-carbohydrate diets (Atkins or ketogenic diets), and low-fat diets.
Low calorie diet
The energy-limited diet means that only 800-1500kcal of calories per day is formed, resulting in a negative energy balance, which can reduce the average weight by 0.4~0.5kg per week. The energy intake per day: carbohydrate (50%~55%), Protein (10% to 15%), fat (20% to 35%). Studies have shown that limiting energy-balanced diet can effectively reduce body weight, adipose tissue weight, visceral fat area and the risk of atherosclerosis.
Light fasting mode is also called intermittent fasting. One type adopts 5+2 mode, which means normal eating for 5 days, and the other 2 days (non-continuous) takes normal 1/4 energy (about 500kcal/day for females and 600kcal for males). Dietary patterns. Meta-analysis showed that light fasting patterns have significantly improved weight, visceral fat, blood sugar, and insulin function in overweight and obese patients. Moreover, studies have shown that compared with calorie-restricted diets, light-off diets reduce fasting. Insulin, insulin resistance is more obvious.
Fasting simulated diet (low protein, low carbohydrate but high fat) means limiting calories for 5 consecutive days a month, 50% of normal daily calories on the first day, and 10% of normal daily calories on days 2-4. Studies have shown that this diet can also reduce body weight, waist circumference, BMI, blood pressure, body fat, and IGF-1 levels. However, the study is still a small sample study, and the researchers emphasized that it is not recommended to try a fast-acting simulated diet at this stage.
Low-fat diet and low-carb diet
Low-fat diet is to reduce the amount of fat in food to reduce calorie intake, but does not limit the total amount of food intake. Low-carbohydrate diet is the energy ratio of carbohydrates per day.< 45%, 如Atkins饮食或生酮饮食. 研究显示, 低脂饮食与低碳水化合物饮食均能降低体重, BMI, 体脂和腰围, 效果相当.
Problems faced by obesity diet intervention
Dietary therapy should be performed under the guidance of a doctor. Possible risks during dieting/fasting and re-feeding include: malnutrition; increased fatigue, decreased physical activity; difficulty in long-term maintenance; hypoglycemia; hunger ketosis, ventricular fibrillation, lactic acid Poisoning; vitamin and electrolyte disorders; high uric acid; sudden death syndrome; low consumption of adipose tissue, loss of large amounts of lean tissue (muscle).
Studies have shown that lower than 40% or more of the calorie intake from carbohydrates leads to a higher risk of death, with a large amount of animal protein and fat (meat, butter and cheese) instead of carbohydrates. People who replace carbohydrates with vegetable protein/fat (beans and nuts) have a higher risk of death. The ketogenic diet, the Atkins diet, etc. contain a lot of meat.
With the prolongation of treatment time, various weight loss programs have the problem of weight 'rebound'. The low compliance with dietary diet is the main reason for the increase in body weight 'rebound', and factors such as decreased basal metabolic rate are also involved. The 'best' weight loss diet encourages obese individuals to choose the diet that is most likely to be long-lasting. After successful weight loss, increased physical activity can effectively maintain energy balance to improve long-term compliance and success rate.
