What is said in the title is not an exaggeration. In developed countries, more than half of the adult population are overweight, with about a third suffering from obesity. Every year the situation is getting worse, obesity is “getting younger”, becoming a problem not only for adults but also for children and adolescents. According to experts of the World Health Organization, the spread of obesity in the world has already reached the scale of the epidemic.
How to determine what should be a normal body weight? Usually use the formula proposed in the XIX century by the famous French anthropologist Paul Broca: the ideal weight in kilograms is equal to the height in centimeters minus 100.
Excess weight by 10-30% corresponds to the first degree of obesity, by 30-50% – the second; 50-100% – the third. Already at the first degree, some troubles begin to appear, and an excess of mass of one and a half to two times is considered to be a serious disease that is subject to compulsory treatment.
Pure fat in a healthy person contains 10-20 kg (women more than men). Given its high calorific value (9.3 kcal/g compared to 4.1 kcal/g for glucose), it can be calculated that people have a constant supply of “fuel” of about 100-180 thousand kilocalories. This is enough to ensure the energy needs of the body for 40 days. But since fat is constantly spent on various needs, its depot has to be replenished. In young and middle-aged men, daily energy consumption ranges from 2,600 kcal with light work to 5,000 kcal with heavy physical labor.
It is curious that even if a person does not do anything, but rests in a comfortable chair, in order to maintain the so-called basic exchange, he still needs to take out and put 1600-1700 kcal.
Basal metabolism consists of many factors, and energy is expended on the work of the heart, the necessary electrical processes and chemical transformations in the cells, the preservation of muscle tone, and the maintenance of body temperature. In men, all these processes are more intensive, therefore, with the same body mass, women alone need 10-15% less energy and, consequently, food.
Fats are required by the body not only to have a reserve of calories but also to absorb fat-soluble substances, including vitamins A, D, E, and K. Cell shells are built from fats, fatty tissues serve as pads between the organs and good protection against cold. The daily need for fats with an average load of 80-100 grams per day for an adult. Of this amount, 70% should fall on vegetable oils and 30% on animal fat (including butter). A person prone to obesity should not lean on fats. The extra three walnuts per day (about 100 kcal) yield 4.5 kg of weight per year.
Note that in contrast to many substances, the excess of which is excreted from the body, the fat is either utilized, burning in the work, or deposited in the form of reserves. For this purpose, there are special fat-storing cells – adipocytes. With natural secretions, including through the sebaceous and sweat glands, only 5% of the absorbed fat leaves the body.
WHAT IS FAT AND FROM WHERE IT TAKES
Simple fats are compounds of triatomic glycerol with three fatty acids and include only three chemical elements – carbon, hydrogen, and oxygen. It should be remembered that a person can synthesize fat from carbohydrates. This is especially noticeable on beer lovers; their distinguishing feature – “beer belly” (although beer does not contain fat).
The fats found in the body of different animals differ in the length of the fatty acid chains and the presence of double bonds in them. The smaller the double bonds, the tighter the fatty acid molecules are adjacent to one another, and the fat is harder. Vegetable fats, even in the refrigerator, remain liquid. The body is able to build and shorten chains, and therefore it can be satisfied with any fat. Still, the consumption of animal fats, including butter, is mandatory for humans – only they contain vitamins A and D (carrot and ergosterol contain their predecessors in carrots and yeast).
Vegetable fats contain essential for human polyunsaturated fatty acids – linoleic and linolenic. They are so important to the body that they are considered vitamins (vitamin F). In addition, vegetable oils are a source of vitamin E, which in animal products is only found in the liver.
It is curious that the heart can use fatty acids for work, but feed the brain with pure glucose. Muscles at low load use glucose, and with an increased load, they switch to fats. Consequently, the bustle of home and kitchen affairs “eats” glucose, without affecting fat reserves.
In addition to simple fats, there are complex, including trace elements, often phosphorus. Such fats have a different structure, an example of which is cholesterol. It is necessary for man to build cell walls, the synthesis of hormones, and other things. Simple and complex fats are also called lipids.
The overwhelming majority of fats in the intestine are cleaved (lipolyzed) by the enzyme lipase, which is secreted with pancreatic juice. Bile emulsifies particles of fat, turning them into the smallest droplets available for lipase. As a result, fat is decomposed into its constituent fatty acids and glycerin, which are absorbed into the walls of the small intestine. From a large set of fatty acids in the intestinal mucosa, specific human fat is synthesized. Fat molecules, combining together and connecting with proteins, form larger droplets – chylomicrons, which with lymph flow into the thoracic lymphatic duct, from where they penetrate into the bloodstream and further along the capillaries – into all organs. Capillary walls secrete a special enzyme – lipoprotein lipase, which detaches fatty acids from their carrier, glycerin, after which free fatty acids are captured by the tissues. The most active are the capillaries of the fat depot, lungs, and heart. In humans, more than 80% of fat is formed by fatty acids, and only 20% is obtained from carbohydrates. But the camel synthesizes almost 100% of its fat from grass and water.
HABIT OR DISEASE?
Apparently, primary obesity is associated with heredity. It is noticed that if both parents are obese, then in children it occurs in 78% of cases, if one is in 56%, and if the parents are of normal weight, then the probability decreases to 14%. Nevertheless, despite the genetic predisposition, obesity is an acquired disease. The body has a mechanism that maintains a constant level of fat (lipostase). In obesity, the balance between calorie intake and consumption is disturbed, fat accumulation takes place and then its amount stabilizes at a new, higher level. The regulation mechanism can break down for various reasons, for example, due to constant overeating. A bad habit of eating more food than is required, combined with heredity, turns into a disease.
The development of obesity can go on in two scenarios. In the first case, the number of fat cells (adipocytes) remains constant, but there is an accumulation of fat in each of them. The normal adipocyte volume is 0.3 microliters, the limit is 1 microliter. Consequently, how much fat or mine, but the depot will not increase by more than 3-4 times. This form of obesity is called hypertrophic and usually develops in adulthood.
In the second variant, the fat cells multiply, and their number increases. New cells secrete a substance that increases the appetite. The number of cells, and at the same time, the excess body weight increases to exorbitant values. This type of obesity (it is called hyperplastic) is often associated with the hereditary predisposition and begins much earlier. The greatest risk for the development of obesity of this kind occurs in adolescence, during pregnancy, and in menopause.
According to the location of fat accumulations, there are two types of simple obesity: android (male) and gynoid (female). Gynoid type of obesity is also called pear-shaped because fat is deposited mainly on the hips and buttocks. By analogy, the android type, in which fat deposits are mainly on the abdomen and chest, is called apple.
By the way, the cells forming deposits of the gynoid type are able to synthesize and accumulate female sex hormones that support women’s postmenopausal sexuality and prevent atherosclerosis. Therefore, a small fat layer in the hips for women is simply necessary.
The Android type gives more complications than the gynoid one. Fat deposits in the abdomen are often located not under the skin, but around the internal organs (visceral, or “internal”, obesity). In general, hyperplastic, android, and visceral obesity is considered more dangerous, and hypertrophic, gynoid, and subcutaneous – less dangerous. The first combination brings the whole bunch of trouble, the second – only individual flowers. This bouquet, in addition to simple inconveniences, includes atherosclerosis, coronary heart disease, cerebral thrombosis, liver obesity, varicose veins, diabetes, gout, arthrosis, chondrosis, and cancer.
HOW WE’RE ADJUSTED
It has long been established that the so-called hypothalamus takes the most active part in the regulation of fat metabolism in the brain. The idea of the existence of a food center in the hypothalamus was expressed by IP Pavlov back in 1911. He believed that the feeling of hunger and satiety depends on the filling of the stomach. To some extent, this assumption is true now. The Indian scientist B.C. Anand discovered in 1951 that the food center of the hypothalamus consists of two parts: the center of hunger (appetite), located in the lateral nuclei, and the center of saturation, which is located in the median nuclei.
Irritation of the hunger center with a weak current causes the animals to actively seek food and absorb it uncontrollably, which ultimately leads to obesity. On the contrary, irritation of the saturation center in animals causes a state of pleasure and even bliss at the complete rejection of food, but the result is exhaustion. As Anand showed, the mechanism is not limited only to the feeling of satiety. The center of saturation is connected with the center of hunger by the inhibitory nerve fibers. At saturation, the center of hunger is inhibited. Such a mechanism in normal physiological conditions protects people from overeating.
Both centers interact with the rest of the brain, attracting emotions to food, shaping behavior and habits. Selective destruction of the medial nuclei (in rats, cats, and primates) causes a strong hunger, unrestrained desire for food, and a tenfold excess weight. With the destruction of the lateral nuclei develop a persistent rejection of food, exhaustion, and death from starvation.
It was found that adrenaline-like transmitters of nerve impulses stimulate a saturation center, resulting in a feeling of satiety. Drugs such as phenamine, which were used during the war to suppress feelings of hunger and drowsiness, were tried to be used in peacetime, but, unfortunately, it turned out that they all cause side effects and, if taken for a long time, no longer work.
The center of saturation is regulated by serotonin. We began the development of drugs that influenced precisely this center, but the resulting drug, fenfluramine, caused many side effects and is now banned.
The food center can be affected by various hormones, in particular, vasointestinal (vascular-intestinal) polypeptide, intestinal enterohormones, which are released in response to food intake and suppress the appetite, etc. Many mechanisms are known that allow one to regulate eating at the table, but not body weight.
In 1994, an American scientist J. Friedman discovered a new peptide hormone, leptin. It is synthesized by fat cells – adipocytes, and in those periods when they are filled with fat and, as it were, “fed”. Leptin production is stimulated by insulin. With blood flow, leptin enters the brain and is captured by the medial nuclei of the hypothalamus, causing a feeling of satiety and the production of inhibitory signals to the hunger center. At the same time, the center of hunger suppresses a particular neuropeptide Y, which stimulates eating behavior, insulin production, and, finally, the accumulation of fat in adipocytes. The circle thus closes excess fat — leptin — suppression of hunger — reduction in the production of neuropeptide Y — cessation of the release of excess insulin and a decrease in the release of leptin. With the threat of losing weight, everything goes in reverse order.
In 1997, an article appeared by a group of scientists, which states that with excessive formation, leptin activates the sympathetic nervous system, which, among other things, acts through the newly discovered beta-3-adrenoceptors (previously it was believed that they are only of two types) activates lipolysis of adipose tissue, that is, its disintegration with subsequent combustion (especially with visceral obesity).
It would seem that excessive accumulation of fat suggests that there is little leptin in the body. But among patients with primary obesity, only about 20% have leptin deficiency, and in 80% this peptide is present in excess. Apparently, the latter has decreased sensitivity to leptin, that is, leptin is plentiful, but there is little confusion. A similar picture is observed in type 2 diabetes: there is a lot of insulin, but the cells do not respond to it.
Figuratively lipostasis (the mechanism of fat balance) can be imagined as a barrel with two pipes: fat flows in through one tube and flows out through the other. In primary obesity, lipostasis transfers the setpoint of body weight (conditionally, a tube with fat flowing out and burning at the exit) to a higher level, taking the actual amount of fat as insufficient.
In general, primary obesity is defined as a manifestation of absolute or relative leptin deficiency against the background of eating disorders and physical inactivity.
HOW TO FIGHT ANY EXTRA WEIGHT
Australians, the third-largest in obesity in the world, in 2002 spent $ 250,000 on all kinds of slimming products. And no effect. In the new year, the government decided to spend the same money on the construction of sports facilities. See if it helps.
Unfortunately, the use of new tools such as leptin and beta-3-adrenomimetics, in many cases, allows you to reduce body weight and maintain it at the level of the norm (while observing the usual medical recommendations), but this is still not a complete cure for obesity as a disease. The same happens in the treatment of diabetes with insulin and hypertension – antihypertensives. The manifestation of the disease is eliminated, but not the disease itself.
Currently, as before, in the treatment of obesity in the first place is a diet. It makes no sense to paint it in detail, but we emphasize that fatty dishes, sweets, chocolate, confectionery, muffins, ice cream, and other sweets should be absolutely excluded from the diet – only balanced in all indicators of food and not more than 1,200 kilocalories per day. Aspartame and saccharin are recommended to compensate for the sugar limit. Spicy and salty snacks and dishes are not recommended. In addition, once a week it is necessary to arrange fasting days: for hard work – a piece of boiled meat with a vegetable side dish, cottage cheese, tea (all without sugar); during light work – vegetable and (or) fruit days. More severe restrictions may be prescribed only by a dietitian.
Compulsory daily physical exertion to mild fatigue: walking, jogging, cycling, swimming, special therapeutic exercises. Sex is also recommended, but according to age. If there are no contraindications, massage, mineral baths, and a bath are very useful.
Pharmacotherapy includes the use of agents that stimulate the breakdown of fats, enhancing the effect of insulin (biguanides), as well as inhibiting the absorption of fats from the intestine (orlistat). To suppress feelings of hunger, central anorexigenic (appetite suppressant) drugs are used – adrenomimetics (dezopimon, isolipan, phenylpropanolamine). Unfortunately, they all cause an increase in blood pressure and other disorders of the cardiovascular system and therefore are not well tolerated. The drug sibutramine, which activates the saturation center as a result of the accumulation of serotonin in the brain and simultaneously depresses the hunger center, has been created. After receiving it, the person sits down at the table as if already full and eats no more than is required. Unfortunately, this drug is far from perfect; it can be used only as prescribed by a doctor.
Anorexants-fillers help reduce hunger. These substances contain agar or cellulose. They swell in the intestines, causing a feeling of satiety, but not absorbed. By the way, it is useful to take laxatives from time to time – both saline (sulfate magnesia) and vegetable, and also, given that adipose tissue retains water, are diuretics from potassium-sparing, for example, triampur or verospiron.
Surgical methods of removing part of the fat or even part of the intestine are not practical: such an operation is expensive, and the effect is only temporary.
In general, with an individual selection of drugs and the will to eliminate obesity, the goal can be achieved. To lose weight, in general, is easy – it is difficult to stay on the achieved result.
In addition to Brock’s formula, there are other ways to calculate the ideal weight. Recently, an indicator such as body mass index (BMI) has been increasingly used. To determine BMI, body weight in kilograms should be divided by the square of height, expressed in meters. If the resulting value falls in the range of 18.5-25, then the weight is normal; from 25 to 30 – overweight; over 30 – obesity. And if the BMI is below 18.5, this corresponds to a deficiency in body weight.
According to scientists, the main factors leading to the spread of obesity in developed countries are a decrease in physical activity and a change in the structure of nutrition. The manual labor in the production has practically disappeared, washing machines and vacuum cleaners have significantly simplified housework. More and more families have private cars and use them to travel even for short distances. In public places, escalators, elevators, and automatic doors are increasingly being installed. At the same time, increased consumption of foods containing large amounts of fat and well-digestible carbohydrates. This lifestyle change creates the prerequisites for the manifestation of a genetic predisposition to obesity.
Simple fats are triglycerides consisting of three fatty acids, combined with trihydric alcohol glycerol. On the three-dimensional model, oxygen is shown in red, blue is carbon, and white is hydrogen.
The image of adipocyte cells of adipocytes obtained with a scanning electron microscope is an increase of 440 times.
Scheme of hunger and saturation. The center of hunger and the center of saturation in the intervals between meals are at rest. Irritation of the hunger center leads to overeating and obesity, irritation of the saturation center leads to starvation and exhaustion. Destruction of the center of hunger – exhaustion, destruction of the center of saturation – obesity. The hunger center is activated by nervous influences – “empty stomach”, contraction of the intestine, and humoral effects – “hungry blood” (lack of glucose and other nutrients), excess thyroid hormones, lack of pancreatic hormones, and others. The saturation center is activated in the same way, only with the opposite sign: overflow of the stomach and intestines, a saturation of the blood with nutrients, decrease in the production of hormones by the duodenum, the thyroid gland, and other organs. Activating the saturation center slows down the hunger center. The hunger center is very sensitive to the reflex for a while, it is activated purely mentally (talking about food, its smell) and, oddly enough, with stress (perhaps this is where the tradition of commemoration comes from). The pleasure of eating can bring the process of saturation itself to voluptuousness, which leads to obesity. In some people, grief, anxiety, depression can suppress the feeling of hunger, leading to emaciation. For phlegmatic people, fullness is characteristic, for choleric persons – thinness. In general, a well-organized mechanism can deteriorate from purely mental factors.
What matters is not only the total amount of fat but also how it is distributed in the body. In women, body fat is usually located on the thighs and buttocks, which gives the figure a pear shape. Men tend to accumulate fat in the abdomen, acquiring some resemblance to an apple. Obesity of the “apple” type causes more health complications. Normally, the ratio of waist circumference to hip circumference does not exceed 0.8 in women and 0.95 in men.
Scheme lipostasis. In the body, there is a balance between the amount of fat that comes from food, and the fat consumed for different needs (burned). The balance regulator is the peptide hormone leptin. With a lack of leptin, a stable level of the fat depot in the body rises.