Wang Lixiang and Wang Guiqiang: Weighing Your Weight on World Obesity Day - "Preventing "Underweight" Weight Management Part 1"

Obesity is a common metabolic syndrome. The WHO has long included obesity in the list of diseases and believes that it is the world's largest chronic health problem for adults and a risk factor for major chronic diseases such as cardiovascular and cerebrovascular diseases. The number of people who die from obesity each year is as high as 4 million, so how to manage weight scientifically is particularly important. The "Chinese Expert Consensus on Precision Health Communication" points out: "Faced with the in-depth development of today's medical science and the growing health needs, it is difficult for health communication workers to generalize; faced with the complexity of today's diversified information and health media, it is difficult for the general public to obtain accurate information and feel at a loss; faced with the unpredictable changes in today's ecological environment, it is difficult for social and human health to adapt and speed up the update." Therefore, the communication of weight management also needs to start with precision health communication, that is, to accurately locate the weight management goals in terms of spatial position, time perception, and changes in the world, focus on the targets of body physiology, mental psychology, and social ethics, and carry out the content of deepening health communication resources, carefully cultivating health communication channels, and infecting health communication audiences, and establish a weight health management communication system that covers the entire life process, all aspects, the entire cycle, and a three-dimensional and full-chain. Extracted from the Citizen Weight Management Guidelines published by the "Journal of Chinese Research Hospitals - Expert Consensus on Precision Health Communication in China", today's first article is "Preventing Weight Loss, Part 1".

The management of "not overweight" means: moving the threshold of overweight management forward and transforming from disease-centered to health-centered. "Not overweight" includes people who are underweight and within the normal range, that is, the body mass index (BMI) is less than 24.0 kg/m2, but there are potential high-risk factors that cause obesity, such as inadequate understanding of obesity, incomplete knowledge reserves, and unscientific lifestyles. Therefore, we will focus on the potential high-risk factors that cause overweight, emphasize the word "prevention", and mainly start from the three aspects of "pre-recognition, early warning, and prevention".

1. Pre-recognition of the Three Consciousnesses

"Pre-identification" is to identify high-risk factors for possible overweight or obesity in advance. High-risk factors for obesity mainly include unbalanced diet, irregular diet, insufficient activity, insufficient sleep, family history of obesity, metabolic-related diseases, etc. Take possible intervention measures in time for the above factors to prevent overweight or start weight management as soon as possible.

1. Predictive identification based on source: Predictive identification based on source means to identify the etiology and causes of overweight or obesity, identify the risk factors of high-risk patients, and take targeted preventive measures. For example, factors such as heredity and drugs. When such factors are found, early prevention should be carried out, and attention should be paid to cultivating healthy eating habits and lifestyles, and raising vigilance. Obesity can be divided into two categories: simple and secondary [9]. According to the age of onset and adipose tissue pathology, it can be divided into two types. (1) Constitutional obesity (juvenile-onset obesity), characteristics: ① family history of obesity; ② obesity since childhood, generally from about six months old due to overnutrition until adulthood; ③ systemic distribution, fat cells are hyperplastic; ④ dietary restriction and increased exercise have poor effects, and are less sensitive to insulin. (2) Acquired obesity (adult-onset obesity), characterized by: ① It occurs between the ages of 20 and 25, and is caused by overnutrition and genetic factors; ② Obesity is mainly in the limbs, with simple hypertrophy of fat cells without obvious proliferation; ③ Diet control and exercise have good therapeutic effects, and insulin sensitivity can be restored to normal after treatment.

2. Dynamic prognosis: Dynamic prognosis is an important method for long-term observation and monitoring of body weight. Patients should develop the habit of monitoring their own weight dynamically, continuously and repeatedly in their daily lives. When they find that their weight has increased or decreased a lot in a short period of time, they should analyze the reasons in time. For patients who have been identified as having obesity tendencies, they should continue to be closely monitored and observed after management, and the management effect should be evaluated until their weight stabilizes.

3. Immediate precognition: Obesity is becoming the "culprit" of many chronic diseases. Studies [11-12] show that the mortality rate of obese men aged 25 to 34 is 12 times higher than that of the general population; the increase in mortality rate decreases with age, which shows that obesity in young people is more dangerous. However, the mortality rate of obese people aged 65 to 74 is still twice that of people with normal weight, suggesting that the awareness of the necessity of weight management should be improved during the medical process, and special attention should be paid to the management of obese people without obvious discomfort symptoms.

(II) Early warning "three warnings"

"Early warning" is an early warning model based on family history related to obesity based on genetics, high-risk individuals based on modern medical testing and screening, and high-risk values ​​obtained through modern medical big data analysis. Through the effective and standardized implementation of "precise positioning" of individuals who may become obese, advance warning information is issued to achieve the purpose of preventing problems before they occur. Healthy lifestyle, regular physical examinations to monitor indicators such as blood lipids, blood sugar, blood pressure, homocysteine, liver function, glycosylated hemoglobin, blood uric acid, etc., and a positive attitude towards life.

1. Indicator warning: (1) BMI: Different organizations at home and abroad have proposed different standards for weight classification based on BMI size [13], see Table 1. The survey results of the China Obesity Working Group show that compared with normal weight people (BMI: 18.5-23.9 kg/m2), people with BMI ≥ 24 kg/m2 have a 3-4 times higher risk of hypertension, a 2-3 times higher risk of diabetes, and a 3-4 times higher risk of having two or more risk factors (i.e., risk factor clustering, mainly including high blood pressure, high blood sugar, high serum total cholesterol, high serum triglycerides, and low serum high-density lipoprotein cholesterol). More than 90% of obese people with BMI ≥ 28 kg/m2 suffer from the above diseases or have risk factor clustering. (2) Waist circumference (WC): The "Guidelines for the Prevention and Control of Overweight and Obesity in Adults in China" and the "National Health and Family Planning Commission of the People's Republic of China - Determination of Adult Weight" define central obesity in adults directly using waist circumference, see Table 2. The survey results of the China Obesity Working Group show that if the waist circumference of men is controlled below 85 cm and that of women is controlled below 80 cm, about 47% to 58% of the risk factors may be prevented from gathering. (3) Waist to hip ratio (WHR): Based on the waist to hip ratio, the obese population can be defined as follows, see Table 3. Studies have shown that the waist to hip ratio can be used as an independent and objective body composition indicator to reflect the characteristics of body fat distribution. (4) Body fat percentage (BF%): Body fat percentage refers to the ratio of the mass of all fat tissue in the body to body weight (mainly subcutaneous fat and visceral fat). The WHO and the American Society of Bariatric Practitioners (ASBP) have proposed different standards, see Table 4. my country often adopts the WHO standard. The normal range of BF% for adults is: 20% to 25% for women and 15% to 18% for men. If the BF% is too high, the body weight that exceeds the normal value by more than 20% can be considered obese.

Table 1 Recommended weight classification for adults (kg/m2)

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Note: BMI is body mass index

Table 2 Classification of central obesity in adults

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Table 3 Classification of waist-to-hip ratio in adults

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Note: WHR is waist-to-hip ratio

Table 4 Obesity standards for body fat percentage in adults

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Note: ASBP is the American Bariatric Medical Association, BF% is body fat percentage

2. Behavioral warning: From the perspective of related behaviors, the main unhealthy behaviors of overweight and obese residents include: (1) Unbalanced diet: Eating disorders mainly include lack of food, partial eating, fasting, snacking, late-night eating, and overeating. (2) Insufficient exercise: Regular exercise can consume excess calories and fat in the body, making the body healthier. The body has a certain adaptability. Insufficient exercise will cause the body's adaptive disorder, which will not only fail to achieve the effect of weight loss, but sometimes even cause weight gain. While insisting on exercising, you should also pay attention to the body's tolerance. Excessive exercise will also cause damage to the body. (3) Irregular work and rest: In recent years, many young people have irregular work and rest. Bad living habits such as staying up late, sitting for a long time, not exercising, and overeating are the main factors for the high incidence of obesity. Therefore, it is necessary to increase the attention of young people to obesity, prevent it before it happens, and advocate a healthy lifestyle. Circadian rhythm is involved in lipid balance in the body. Many metabolic factors including enzymes, transport proteins and hormones also show circadian rhythm. Lack of sleep will reduce the release of leptin in the body, leading to increased food intake, endocrine disorders and obesity. Staying up late can easily disrupt the biological clock rhythm, causing the liver to be unable to eliminate toxins in the blood in time, resulting in waste accumulation in the body, causing obesity. These unhealthy lifestyles are leading us to overweight or obesity, so we should sound the alarm in our hearts and overcome the "three no" lifestyle habits.

3. Mood warning: Psychological factors cannot be ignored. Joy, anger, sorrow, thinking, sadness, fear, shock, mental factors, etc. are also closely related to weight. According to research, obese people eat more than usual when they encounter anxious situations, so being in an anxious state for a long time is also a warning sign of obesity. Related studies have shown that there is a two-way relationship between obesity and depression. They can influence each other and cause each other. Individual obesity can predict the occurrence of depressive symptoms; conversely, individual depression can also predict the occurrence of obesity. The incidence of depression caused by obesity is about 55%, and the incidence of obesity in patients with depression can reach 58%. Epidemiological surveys have shown that mental symptoms are related to obesity and abdominal fat distribution in women; the WHR of middle-aged men is related to depression, anxiety, sleep disorders and other factors.

3. Prevention of "three preventions"

"Prevention" refers to taking measures in advance to prevent things from deviating from the subjective expectation or objective general law. The first thing is to establish a multi-dimensional prevention system covering individuals, families and society, emphasizing the establishment of a new "three-in-one" obesity prevention model of personal prevention, family prevention and social prevention. "Prevention" emphasizes awareness, and "prevention" focuses on measures. Specifically, we should first establish the correct concept, adhere to prevention first, start with children and adolescents, start with preventing overweight, and persist in it throughout life.

1. Dietary prevention: According to the law of conservation of energy, the root cause of overweight or obesity lies in the imbalance between energy intake and consumption. Dietary prevention is to control the energy intake. Encourage the intake of low-energy, low-fat, moderate protein and carbohydrates, and rich in dietary fiber, trace elements and vitamins. WHO and the nutrition community have given a unified recommendation on the intake of dietary fiber, that is, the daily intake per person should be between 25 and 35 g. The "White Paper on Dietary Fiber Intake of Chinese Residents" released by China in 2016 pointed out that the dietary fiber intake of Chinese residents is generally insufficient, and the total daily dietary fiber intake per capita is about 13 g; compared with the recommended amount of dietary fiber in the "Reference Intake of Dietary Nutrients for Chinese Residents" (25-35 g/d), less than 5% of the population can reach the appropriate intake, so nutritionists advocate that most people should supplement a certain amount of water-soluble dietary fiber every day.

2. Active prevention: During the period of maintaining weight, increasing exercise is of decisive significance. Obesity-related diseases must be prevented and treated at the same time, and obesity prevention and treatment should be regarded as an important part of preventing and treating related chronic diseases. Controlling diet and increasing exercise can overcome the adverse factors caused by simply reducing dietary energy. The combination of the two can prevent the basal metabolic rate from decreasing due to too low energy intake, and achieve better weight loss effects. Short-term high-intensity exercise is an anaerobic exercise, which is mainly provided by glycolysis. Moderate-intensity and long-term exercise is mainly provided by fat and is aerobic exercise. Therefore, in order to increase fat consumption and reduce the amount of fat stored in the body, moderate-intensity and long-term exercise, that is, endurance exercise, is required. The Chinese Residents' Dietary Guidelines recommend: 6,000 steps of exercise per day. It is recommended to accumulate various activities every day to reach an activity equivalent to 6,000 steps, which is approximately equivalent to 40,000 steps per week.

3. Emotional prevention: Studies have shown that obesity can cause damage to cognitive and motor functions. Similarly, emotional states can affect cognitive processes, and negative emotions such as sadness, disgust, fear, anger, anxiety, and depression can lead to weight gain. Obesity and emotional problems interact and influence each other, and should not be underestimated. Physical and mental health is the real health. Studies have shown that obesity increases the risk of Alzheimer's disease and depression. "Sanyin Jiyi Bingzheng Fanglun" officially lists joy, anger, worry, thinking, sadness, fear, and shock as internal causes of disease. However, under normal circumstances, the seven emotions play a coordinating role in the physiological functions of the body and will not cause disease. On the one hand, the prevention of obesity should not only focus on diet and exercise, but also on the construction of the family environment. On the other hand, intervention for obese children should not only focus on diet and exercise, but also help children and their families improve their emotional regulation ability and jointly build a harmonious family.

author:

Wang Guiqiang is the director of the Department of Infectious Disease Control at Peking University, professor, and doctoral supervisor. He is a national health science popularization expert and the editor-in-chief of "Immunity is a Good Doctor", which won the 2020 "China Good Book" Award.

Wang Lixiang is the former director of the emergency department of the Third Medical Center of the General Hospital of the People's Liberation Army, professor, and doctoral supervisor. He is a national health science popularization expert and co-editor of "Immunity is a Good Doctor", which won the 2020 "China Good Book" Award.