Exercise and Body Composition Control
There are many reasons for obesity, but the direct cause is the excessive intake of calories, which exceeds the calories required by normal people for a long time. Due to a lack of knowledge about how obesity occurs and the correct ways to prevent it, some unscientific techniques are used by people who blindly pursue physical beauty. Sometimes they are too fast, get half the result with half the effort, or induce some diseases and damage health.
Overweight and obesity
Overweight refers to the weight that exceeds the standard weight. The normal weight is determined according to height and body type. Obesity refers to a state of excessive body fat. This also means that the actual content of body fat and its percentage in total body weight, that is, the body fat percentage exceeds the upper limit of normal. It is generally believed that the body fat percentage of men exceeds 25%, and that of women over 35% are obese. These two concepts are not completely the same. Being overweight does not necessarily mean that the body fat content is exceeded, but it may also be caused by increased body lean mass. The factor that impacts physical health and can lead to chronic diseases is increased body fat content, not increased weight.
The etiology of obesity
The etiology of human obesity has not yet been clarified. Several factors need to be considered: genetic factors, nervous system factors, eating habits, metabolic disorders, especially energy supply and demand disorders, and endocrine regulation dysfunction.
Obesity is often related to genetics. According to statistics, the incidence of obesity in children of normal parents is 10%; one of the parents is obese, and the incidence of obesity in children is 50%; both parents are obese, and the incidence of obesity in children is as high as 70%. Identical twins grow up in the same environment, and their weights are similar; even if they grow in different environments, their importance is smaller than the difference between fraternal twins. Obesity patients have not only hereditary obesity but also the location of fat distribution and bone state. The genetic tendency of obesity is also manifested in the number of fat cells and (or) the increase in cell volume.
According to the latest research, obesity is a polygenic genetic disease. There are more than 200 genes or chromosomal regions related to obesity. The “contribution rate” of genetics to obesity accounts for 40%-60%, and about half of obesity is caused by obesity. Determined by genetics. These genes and proteins form a network in the human neuroendocrine system. Controlling the expression of a certain gene and protein alone cannot achieve the effect of weight loss. It is necessary to control and regulate the entire network system to solve the problem of obesity truly.
Diet, living habits and social, environmental factors
Obese people often have a history of eating more, eating a larger amount, preferring to eat sweets, or adding food in the middle of each meal to cause excess energy; they have the habit of eating before going to bed and eating more at dinner. Too little physical activity or bed rest due to illness, low-calorie consumption, and obesity.
Changes in the social environment have a certain relationship with obesity: with the improvement of living standards, people consume more calories and consume too little energy, which leads to obesity; in addition, obesity is related to family education. Studies have found that only children or the youngest children in a family are prone to obesity. The main reason is the mistaken belief that the fatter the baby is feeding, the better the child is over-nourished from lactation; over-spoiling, develops bad habits, such as too many snacks, especially sweets; unnecessary nutritional drugs stimulate appetite and increase appetite. It is now recognized that child overnutrition is the main cause of obesity in childhood and adulthood.
Scientists believe that regular eating habits are more beneficial to human health, and when to eat is more important than what to eat. Some experts believe that preventing obesity and diabetes can allow children to drink white water. There are many different theories on the environmental and social factors of obesity. For example, inflammation can lead to obesity, diabetes, and heart disease. They found that people who are obese have more inflammatory factors. The chemical pollution theory is one of the causes of obesity due to endocrine disorders caused by chemical pollution.
The viral theory believes that “viral infection” is one cause of obesity. Viruses can be developed to prevent obesity in the future. Mental factor theory believes that when the mind is overworked, it will suppress appetite by stimulating the vagus nerve. Stimulation of the vagus nerve will make the body release insulin, which will increase appetite.
Interaction Between Genetics and Environment
Is the obesity epidemic caused by genetics or environmental factors? One theory believes that the main driving factor is the environment. In contrast, the other theory believes that heredity is the main influencing factor, but different lifestyle habits can amplify or weaken the impact of genes on human health. Recently, American researchers discovered that sitting for a long time can “amplify” the “efficacy” of obesity genes. Walking for a short period every day can offset the effect of obesity genes on health. In a two-year investigative trial involving 7740 women and 4564 men, after insisting on walking every day, the body mass index (BMI) of at least half of the people with genetic factors of obesity decreased to varying degrees. The American Heart Association held its annual meeting in California and reported that insisting on walking can offset the effects of obesity genes on health. This is the first time that the academic community has studied the relationship between living habits and obesity genetic quality. Researchers from the Harvard School of Public Health found that large amounts of sugar-sweetened beverages can increase genetic susceptibility to high body mass index and increase the risk of obesity.
The causes of obesity are very complicated. Everyone has their unique causes of obesity. Recognizing this is very important for the treatment of obesity. Only thinking that obesity is caused by gluttony is incomplete and will mislead people to lose weight. Studies have shown that some obese people consume less than normal-weight people of the same age and sex analyzes but do less physical activity.
Pathogenesis of Obesity
Regardless of the cause of obesity, the mechanism is the same: that is, dietary energy intake exceeds the body’s consumption to achieve a positive balance of calories, excess energy is stored in the body in the form of fat and fatty tissue increases, resulting in obesity.
Health Problems Related to Overweight And Obesity
Generally speaking, overweight and obesity have a significant correlation with mortality. The main high mortality diseases related to them are heart disease, hypertension, type 2 diabetes, certain cancers, gallbladder diseases, osteoarthritis, etc.
- Changes in normal body functions
- Increased risk of certain diseases
- Negative psychological effects
Body CompositionTest Method
Direct Measurement of Skinfold Thickness
The width of the skin fold in the subscapular region is 9.1 to 14.3 mm for men, with an average of 13.1 mm; for women, it is 9 to 12 mm, with an average of 11.5 mm, and you can diagnose obesity if it exceeds 14 mm; for men in the deltoid area, it is 7.9 to 17.8 mm, with an average of 12.3 mm; The female is 13-25mm wide with an average of 18.1mm wide. For example, if the male is over 23 mm and the female is around 30 mm, it is obese.
Calculate Body Fat Percentage From Skinfold Thickness
The thickness of subcutaneous fat in uniformly obese people is related to obesity. Measuring the thickness of subcutaneous fat reflects the content of body fat to a certain extent. There are many formulas for inferring body density based on the skinfold thickness. The selection of the inferring procedure should consider the subject’s age, gender, and physical characteristics. This test method is simple and practical, can understand the distribution of body fat, and is a common method for monitoring the body composition of athletes.
Determine Obesity By Measuring Waist and Hip Circumference
Waist circumference is an important indicator for the diagnosis of central obesity and is closely related to many chronic metabolic diseases. Males ≥85 cm, women ≥80 cm are obese. Waist-to-hip ratio: male WHR ≥ 0.90, female WHR ≥ 0.85 is obese. A British researcher pointed out that predicting the risk of obesity by waist-height percentage is more accurate than predicting only waist circumference.
Body Mass Index (BMI)
Obesity is diagnosed in the World Health Organization, Britain, and the United States for men>27 and women>25. WHO’s BMI classification standards for adults are as follows:
The application of BMI has its advantages and disadvantages. Benefits: The body mass index method effectively tests body composition with large international samples. It is simple and practical. It is generally used to assess the incidence of obesity in different populations. Disadvantages: BMI cannot evaluate changes in body fat distribution, such as subcutaneous fat or abdominal fat. In addition, overweight and obesity as assessed by BMI do not distinguish between muscle and adipose tissue, so they cannot represent body fat content. Some researchers pointed out that BMI will miss nearly 40% of obese patients, especially the elderly, because of declining body muscle mass. The BMI value will be low and missed.
Bioimpedance analysis (BIA) refers to calculating body composition by measuring the difference in electrical current passing through the body’s fat and non-fat tissues.
Body Density and Volume Measurement
Underwater weighing method: the gold standard for body composition measurement. It mainly calculates fat and lean body weight by measuring the subject’s body density and specific gravity. This method analyzes the corpse’s lean body mass and adipose tissue ratio. This measurement method is accurate but requires special equipment and is not easy to popularize. The result is affected by the residual gas in the lung and the amount of gas in the stomach.
Dual Energy-X-ray Absorption Spectrometry (DEXA)
This method uses the attenuation of dual-energy X-rays to have a certain relationship with the types and proportions of the elements. Elements with small atoms (such as carbon and hydrogen) reduce photon energy to a small degree. In contrast, components with many atoms (such as calcium and phosphorus) can significantly weaken the photon energy. Moreover, the degree of photon energy attenuation can be expressed by a characteristic attenuation coefficient (μ/ρ), and each element has a specific typical attenuation coefficient. When the X-ray or photon source is placed on one side of an object, the intensity of the ray or photon on the other side is related to the thickness, density, and chemical composition of the thing. This attenuation effect is nonlinear. For a homogeneous object, this attenuation effect can be expressed by an exponential equation. The two-photon energy X-ray method has higher accuracy and can determine each trunk part’s bone mineral content, bone density, and fat percentage. It has low radioactivity and does not require a high degree of cooperation from the subject, and the measurement is quick and applicable to the wide scope of the issue. Still, due to its high measurement cost, it has certain limitations in application.
The measurement methods are mainly three-dimensional imaging technology, such as X-ray tomography (CT), magnetic resonance imaging (MRI), etc. These have gradually become the main method of body composition measurement at the level of the tissue system.
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Exercise Weight Loss Method
Overview of Weight Loss Methods
In theory, controlling weight seems to be a simple matter. To maintain weight, the energy consumed in food must be equal to the total energy consumed by the body, which is the sum of RMR, TEM, and TEA. Generally speaking, the body can balance calorie intake and expenditure within a certain range, but the weight will decrease or increase once this balance is broken. Weight loss and gain seem to depend largely on two factors, dietary intake, and physical exercise. Now I think this view is too simplistic. The results of the previous study on the excessive food intake of single-egg twins, the same amount of food intake, their weight gain will be very different. It also shows that everyone’s response to weight regulation is different. When designing weight loss plans for individuals who lose weight, they must pay attention to the differences in each person’s response. Weight losers must also understand this difference to better implement weight loss. Plan. We used to think that people who were slow to lose weight would not cooperate, but now we know that this statement is inaccurate.
The role of physical activity in weight control
In the United States, not exercising is a major cause of obesity. In fact, not exercising and eating too much are equally important in causing obesity. Therefore, increasing the level of physical activity is an important factor for weight loss and weight control.
Changes in body composition caused by exercise
Exercise can change the body composition of the human body. Many people believe that physical activity has little or no effect on changing the body. Even high-intensity conditioning consumes very few calories and cannot significantly lose weight. However, many studies have confirmed that exercise can moderately promote body composition transformation.
The mechanism of body composition changes
How exercise causes changes in body weight and body composition, it is necessary to consider both ends of the energy balance formula. When estimating energy consumption, you need to consider each of the three components of energy consumption: RMR, TEM, and TEA. In addition, it is also necessary to consider the loss of energy in the form of feces (energy excretion), which usually accounts for less than 5% of the total caloric intake. Several possible mechanisms by which exercise changes body composition are as follows.
Exercise and appetite
Some people believe that exercise stimulates the increase consciously increase food intake to balance the energy consumed during exercise. At least for a few hours after strenuous exercise, exercise seems to be a mild food suppressant, and many studies have shown that the total calorie intake per day has not changed when starting an exercise program. Although many people explain that this is evidence that exercise does not affect appetite, a more accurate conclusion may be that appetite is affected (appetite is suppressed) because the extra calories intake does not increase in proportion to the extra calories consumed during exercise.
Exercise and resting metabolic rate
From the late 1980s to the early 1990s, a major research topic of interest to researchers was how exercise affects the composition of energy consumption. It is very concerned about how exercise affects the resting metabolic rate, accounting for 60%-75% of daily calorie consumption. For example, a 25-year-old person has a total calorie intake of 2700kcal per day. His resting metabolic rate only accounts for 60% of the total caloric intake (0.60×2700=1620kcalRMR), and the resting metabolic rate only increases by 1%. An additional 16 kcal will be consumed every day, and an extra 5810 kcal will be finished every year. Only a small increase in resting metabolic rate will result in a weight loss of 0.8 kg per year.
Exercise and food caloric effect
Several studies have proven that personal exercise has a certain impact on increasing the caloric impact of a meal. Whether before or after a meal, simple exercise will increase the caloric impact of a meal, but it is not yet known how exercise affects the caloric effect of food. However, these studies often have conflicting conclusions. Some studies show that exercise reduces the caloric impact, and some studies show that exercise does not affect the caloric effect.
Exercise and body fat mobilization
During exercise, fatty acids are mobilized to provide energy. Several studies have shown that the increase of certain hormones during exercise can speed up the mobilization of fatty acids. Hormones increase sharply during practice, and the hormone levels remain high in the recovery period after exercise for several hours. Other studies have shown that animal adipose tissue is more sensitive to the increase in the sympathetic nervous system or catecholamines during exercise, thereby accelerating the mobilization of body fat.
Partial Weight Loss
Many people, including athletes, believe that exercising a specific body part will reduce the amount of fat in that area. The results of several early studies tend to support the view of partial weight loss. However, subsequent studies have found that even for local exercises, the body still uses almost all of the body’s fat for energy, not just the fat for the local active parts. Partial weight loss is just a myth, and it’s impossible.
Passive Exercise to Lose Weight
People seldom get something for nothing. Although an effortless exercise is ideal, such an exercise often fails to make significant changes in physical health, body composition, or body shape. There are still many people who don’t like to exercise by themselves and hope to use other equipment to help them exercise to achieve the effect of weight loss, such as fat-removing machines, AD abdomen machines, and so on. This kind of passive exercise cannot consume energy. After active exercise and bodywork to promote metabolism, fat can be broken down and consume energy. Products that use vibration to produce a “fat-reducing effect” are likely to cause harm to the body due to the varying degrees of magnetic frequency oscillation. Not only can’t you lose weight but using it for too long can also lead to undesirable consequences. It is easy to cause joint damage and even affect visceral functions. For example, severe systemic vibration may affect the normal operation of the stomach and intestines and inhibit gastric acid secretion. If you take a sitting position, it can also cause spinal muscle strain. Under vibration, edema may also occur in the spinal canal and induce disc herniation.
Exercise intensity and energy consumption
Exercise energy consumption mainly comes from sugar, fat, and protein. Generally, exercise energy consumption is primarily sugar. The greater the exercise intensity, the greater the proportion of sugar consumed by the body. During high-intensity aerobic exercise, sugar provides 90% or more of the body’s energy, and only when the exercise intensity is low, does the proportion of mobilized fat increase. In the late 1980s, various professional organizations recommended low-intensity aerobic exercise to speed up fat loss. They believe that low-intensity aerobic exercise will make the body use more fat as an energy source and accelerate fat consumption. But, during low-intensity aerobic exercise, although the body uses more fat as energy, the total calories consumed by using body fat do not necessarily change. Low-intensity aerobic exercise does not necessarily lead to greater calories in fat. More importantly, low-intensity aerobic exercise consumes fewer calories at a certain time than high-intensity aerobic exercise. Therefore, within the body’s ability to withstand, high-intensity aerobic exercise may have a better weight loss effect than lower-intensity aerobic exercise.
Many studies have confirmed an ideal exercise intensity area in different exercise intensity exercises so that the fat oxidation rate reaches the highest value. In this intensity area, the fat oxidation rate is within 10% of the highest place, and the exercise intensity at this time is within the range of VO2max from 55% to 72%. When the exercise intensity reaches 64% of VO2max, the highest fat oxidation rate, see the figure for details.