What Is Adiposity?

Obesity is a common group of metabolic disorders. When the human body eats more calories than it consumes, the excess calories are stored in the body in the form of fat, the amount of which exceeds normal physiological requirements, and when it reaches a certain value, it becomes obesity. Normal male adults account for 15% to 18% of body weight, and females account for 20% to 25%. With age, the proportion of body fat increases correspondingly. There are various methods for assessing obesity, including anthropometrics, dual-energy X-ray absorption, ultrasound, CT, and infrared induction. If there is no obvious cause, it is called simple obesity, and if there is a clear cause, it is called secondary obesity.

Basic Information

English name

Obesity

Visiting department

Department of Endocrinology, Nutrition

Common causes

Overeating and too little activity, disorders of fat metabolism, genetics, etc.

Common symptoms

Simple obesity has a slow increase in weight and a rapid increase in secondary short-term; often accompanied by or exacerbated hypertension, coronary heart disease, diabetes, hyperlipidemia, gallstones, etc.

Causes of obesity

The main reason is that too much diet and too little activity. Calorie intake is more than caloric consumption, so increasing fat synthesis is the material basis of obesity. Obesity due to fat metabolism disorders.

Genetic factor

The onset of human simple obesity has a certain genetic background. Some studies suggest that one of the parents is obese and their children's obesity rate is about 50%; both parents are obese and their children's obesity rate has risen to 80%. Human obesity is generally considered to be a multi-gene heredity, and heredity plays a prone role in its pathogenesis. The formation of obesity is also related to the interaction of lifestyle behaviors, feeding behaviors, hobbies, climate and socio-psychological factors.

2. Neuropsychiatric factors

It is known that two pairs of neural nuclei related to feeding behavior exist in the hypothalamus of humans and various animals. One pair is the ventral contralateral nucleus, also called the satiety center; the other pair is the ventral lateral nucleus, also known as the hunger center. The central satiety is full when it is excited and refuses to feed. When it is destroyed, the appetite is greatly increased. The two regulate each other and restrict each other. They are in a state of dynamic equilibrium under physiological conditions, so that the appetite is adjusted to the normal range and the normal weight is maintained. When pathological changes occur in the hypothalamus, whether it is the sequelae of inflammation (such as meningitis, post-encephalitis), or trauma, tumors and other pathological changes, if the medial ventral nucleus is destroyed, the ventral lateral nucleus function is relatively high and gluttony is insatiable. Causes obesity. Conversely, when the ventrolateral nucleus is destroyed, the ventrolateral nucleus function is relatively high and anorexia is caused, causing weight loss.

3. Endocrine factors

Many hormones such as thyroxine, insulin, and glucocorticoids can regulate food intake, so it is speculated that these hormones may be involved in the pathogenesis of simple obesity. Obese people lead to hyperinsulinemia due to insulin resistance, and hyperinsulinemia can down-regulate insulin receptors and increase insulin resistance, thereby forming a vicious cycle. Increased insulin secretion can stimulate increased food intake while inhibiting lipolysis, thereby causing fat accumulation in the body. Sex hormones may play a role in the pathogenesis of simple obesity.

Overeating can produce too much gastrointestinal peptide (GIP) through stimulation of the small intestine, which stimulates the beta cells of the islets to release insulin. In the case of hypopituitarism, especially in the case of hypogonadism caused by reduced growth hormone, gonadotropin and thyroid stimulating hormone, special types of obesity can occur, which may be related to reduced fat mobilization and relatively increased synthesis. Clinically, most women are obese, especially those who are pregnant or postmenopausal or take oral contraceptives, which suggests that estrogen is related to fat metabolism. When the adrenal cortex is hyperactive, cortisol secretion increases, which promotes glycogenogenesis, blood sugar increases, and insulin secretion increases, so fat synthesis increases, and cortisol promotes fat breakdown.

4. Abnormal brown adipose tissue

Brown adipose tissue is a type of adipose tissue that has only been discovered in recent years, and corresponds to white adipose tissue mainly distributed under the skin and around the internal organs. The distribution of brown adipose tissue is limited, only in the interscapular region, the back of the neck, the axillary region, the mediastinum, and the periphery of the kidney. The appearance of the tissue is light brown with relatively small changes in cell volume. White adipose tissue is a form of energy storage. The body stores excess energy in the form of neutral fat. When the body needs energy, the neutral fat in the fat cells is used for hydrolysis. The volume of white adipocytes varies greatly with energy release and energy storage. Brown adipose tissue is a heat-generating organ in function, that is, when the body is fed or is stimulated by cold, fat in the brown fat cells burns, which determines the energy metabolism level of the body. The above two cases are called feeding-induced heat production and cold-induced heat production. Of course, the function of this particular protein is affected by many factors. It can be seen that brown adipose tissue, a heat-producing tissue, directly participates in the overall regulation of heat in the body, and radiates excess heat from the body to the outside, making the body's energy metabolism tend to be balanced.

5. Other

Such as environmental factors.

Clinical manifestations of obesity

General performance

Simple obesity can be seen at any age. About 1/2 of the adult obese people have a history of childhood obesity and generally show a slow increase in weight (except for women after childbirth). Weight gain rapidly in a short period of time, and secondary obesity should be considered. The fat distribution is mainly in the neck, torso and head of men, while the abdomen, lower abdomen, chest breasts and hips are mainly in women.

Obese people are characterized by a short, round body shape, a narrow upper and lower face, double chins, a short neck, and a thickened skin fold on the headrest. The chest is round, the intercostal space is not obvious, and the double breasts increase due to the thick subcutaneous fat. When standing, the abdomen protrudes forward and is higher than the plane of the chest, and the umbilical foramen is deep. Obviously short-time obese people can see fine purple or white lines on the sides of the lower abdomen, the upper thighs and the upper part of the inside of the upper arm and the outside of the buttocks. In children with obesity, the external genitals are buried in the subcutaneous fat of the perineum, which makes the penis appear small and short. The fingers and toes are thick and short. The back of the hand is dented due to the thickening of the fat, and the bony process is not obvious.
Mild to moderate primary obesity may be free of any conscious symptoms, and severely obese people are more likely to be afraid of heat, have reduced mobility, and even have mild shortness of breath during activity, and snoring during sleep. May have clinical manifestations such as hypertension, diabetes, gout.

2. Other performance

(1) Patients with obesity and cardiovascular obesity are more likely to have coronary heart disease and hypertension than non-obese people, and their incidence is generally 5-10 times higher than that of non-obese people, especially with thick waist circumference (men> 90cm, women> 85cm) of central obese patients. Obesity can cause cardiac hypertrophy, thickened posterior wall and ventricular septum, cardiac hypertrophy accompanied by increased blood volume, intracellular and intercellular fluid, end-ventricular diastolic pressure, pulmonary artery pressure, and pulmonary capillary wedge pressure are all increased, and some obese people have left ventricle Impaired function and obese cardiomyopathy. The incidence of sudden death in obese patients is significantly higher, which may be related to cardiac hypertrophy, arrhythmia caused by fatty infiltration of the cardiac conduction system, and cardiac ischemia. Hypertension is very common in obese patients and is also a major risk factor for aggravating heart and kidney disease. Blood pressure will recover after weight loss.

(2) Changes in the respiratory function of obesity Obese patients have reduced vital capacity and reduced lung compliance, which can lead to a variety of abnormalities in lung function, such as obese hypoventilation syndrome, clinically characterized by lethargy, obesity, and alveolar hypoventilation. With obstructive sleep dyspnea. Severe cases can cause pulmonary heart syndrome, due to thickening of adipose tissue in the abdominal cavity and chest wall, increased diaphragmatic muscle capacity, reduced lung capacity, poor ventilation, and difficulty in breathing after exercise. Serious cases can cause hypoxia, cyanosis, and hypercapnia. Even the occurrence of pulmonary hypertension leads to heart failure, and this kind of heart failure often responds poorly to cardiotonics and diuretics. In addition, severe obesity can still cause sleep apnea and occasional sudden death.

(3) Sugar and lipid metabolism in obesity. Eating too much calories promotes the synthesis and catabolism of triglycerides. Lipid metabolism in obesity is more active and relative sugar metabolism is inhibited. This metabolic change is involved in the formation of insulin resistance. . Obesity is active with lipid metabolism and is accompanied by metabolic disturbances, such as hypertriglyceridemia, hypercholesterolemia, and low-density lipoprotein cholesterolemia. Disorders of glucose metabolism include abnormal glucose tolerance and diabetes, especially in central obese people. Those who weighed more than 20% of the normal range more than doubled the incidence of diabetes. When BMI> 35kg / m, the mortality rate is about 8 times of normal weight.

(4) Obesity and musculoskeletal diseases Arthritis: The most common is osteoarthritis, which is caused by long-term weight loading, which changes the structure of the articular cartilage surface, and the most common lesions of the knee joint. Gout: About 10% of obese patients have hyperuricemia, which is prone to gout. Osteoporosis: In the past, it was thought that osteoporosis in obese people is rare, but recent studies have found that fat cells of obese people secrete a variety of adipokines and inflammatory factors, which may aggravate osteoporosis and fractures in obese people happened.

(5) Changes in the endocrine system of obesity Growth hormone: The release of growth hormone is reduced in obese people, especially it is not sensitive to the stimulation of growth hormone release factors. Pituitary-adrenal axis: The adrenocortical hormone secretion of obese people is increased, the secretion rhythm is normal, but the peak value is increased, and the ACTH concentration also increases slightly. Hypothalamus-pituitary-gonadal axis: Obese people are often accompanied by hypogonadism, decreased pituitary gonadotropin, and reduced testosterone response to gonadotropin. Male obese people have lower total blood testosterone (T) levels, but mild to moderate obese people have normal free testosterone (FT), which may be due to a decrease in sex hormone binding globulin (SHBG). FT may also decrease in severely obese people. In addition, adipose tissue can promote the conversion of androgens to estrogen, so mammary glands develop in obese men, obese girls, menarche earlier. Adult women with obesity often have menstrual disorders, anovulatory menstruation, and even amenorrhea. The incidence of polycystic ovary syndrome is high. Hypothalamus-pituitary-thyroid axis: Obese people's thyroid gland is less responsive to thyroid stimulating hormone (TSH), and the pituitary gland is responsive to thyrotropin releasing hormone (TRH).

Obesity treatment

The two main aspects of treatment are reducing calorie intake and increasing calorie expenditure. Emphasize comprehensive treatment based on behavior, diet, and exercise, supplemented with medication or surgery if necessary. Secondary obesity should be treated for the cause. Various complications and concomitant diseases should be dealt with accordingly.

Behavior therapy

Through publicity and education, patients and their families have a correct understanding of obesity and its dangers, so as to cooperate with treatment, adopt a healthy lifestyle, and change diet and exercise habits. Consciously long-term adherence is the first and most important measure for obesity treatment.

2. Control diet and increase physical activity

For people who are slightly obese, control the total amount of food they eat, use a low-calorie, low-fat diet, avoid high-sugar and high-fat foods, and keep the total daily calories below the consumption. Do more physical work and physical exercise. If you can reduce your weight by 500-1000g per month and gradually reach the normal standard weight, you don't need to use medication.

Moderate obesity and above must strictly control the total calories. Female patients require a restriction of food intake between 5 and 6.3 MJ (1200 to 1500 kcal) / d. If it exceeds 6.3 MJ / d, it is invalid. Males should be controlled at 6.3 to 7.6 MJ (1500 to 1800 kcal) / d. By this standard, it is expected to lose 1 to 2 pounds per week. Animal foods containing appropriate amounts of essential amino acids should be ensured in the food (accounting for one-third of the total protein content is more appropriate), and the protein intake should be no less than 1 g per kilogram of body weight per day. Fat intake should be strictly limited, and sodium intake should be restricted to avoid water and sodium retention during weight loss, and it is also good for lowering blood pressure and reducing appetite. Also limit sweets, beer, etc. If the weight cannot be reduced for several weeks after the above diet control, the total daily calories can be reduced to 3.4 ~ 5MJ (800 ~ 1200kcal) / d, but the calories are too small, and the patient is susceptible to fatigue, weakness, chills, fatigue, and mental fatigue Etc. must be closely observed. According to research, protein consumption in the early stages of diet therapy caused more weight loss, which led to a rapid weight loss and negative nitrogen balance. When the low-calorie diet continued, a protective nitrogen storage response occurred, and nitrogen balance was gradually rebuilt, so fat consumption increased. However, the caloric value of fat is about 10 times that of protein, so the amount of fat tissue disappeared is significantly less than that of protein tissue, and when protein is synthesized on the contrary, the body weight can be increased instead. This is the body's regulation process after limiting calories. Therefore, diet therapy is often not effective, in which case, exercise therapy should be encouraged to increase calorie expenditure.

The formulation of the amount of activity or exercise should vary from person to person, and in principle adopt a gradual approach.

3. Drug treatment

For severely obese patients, drugs can be used to reduce weight, and then continue to maintain. However, how to better use this kind of drugs in clinic remains to be explored. Medication may produce drug side effects and drug resistance. Therefore, the indications for drug treatment must be carefully selected, and decisions may be made based on the individual benefits of the patient and the possible benefits and potential risks.

4. Surgical treatment

Short jejunum surgery, short bile duct pancreas surgery, short stomach surgery, gastroplasty, vagotomy and gastric balloon surgery are available. Surgery is effective (referring to a weight loss of> 20%) at a rate of 95% and a mortality rate of <1%. Many patients can obtain long-term effects, and preoperative complications can be improved or cured to varying degrees. However, surgery may be accompanied by malabsorption, anemia, and narrow pipes, which have certain risks. It is only used for severe obesity, weight loss failure and serious complications, and these complications may be improved by weight loss. Before the operation, the patient's general condition should be fully estimated, especially diabetes, hypertension and cardiopulmonary function, etc., and corresponding monitoring and treatment should be given.