The relationship between obesity and immunity, smoking, gender, occupation, and the concept of weight
XI. Obesity and Immunity
"Know yourself and know your enemy, and you will never be defeated" is a famous ancient military term. If a person is not sick, their own defense and recognition capabilities are very perfect. This system is what people often call immunity.
Immunity is the physiological function of the body's immune system in recognizing "self" and "non-self" components and rejecting abnormal substances. When the body malfunctions, it can cause damage to its own tissues. Its main functions are threefold: defense (anti-infection immunity, which, when excessive, manifests as allergic reactions); maintaining homeostasis (removing old or damaged cells, which, when excessive, manifests as autoimmunity); and immune surveillance (removing abnormal cell variants that frequently occur in the body, which, when weakened, can lead to malignant tumors in the elderly). Obese people may appear robust, but in reality, they are "all show and no substance." What is the immune function of obese people?
In daily life, you'll see that obese people are prone to catching colds and don't recover quickly; obese people are often breathless after exercise; and obese people often develop lumps under their skin. These all indicate that obese people have problems with their defense system and low immune function.
Whether the weakened immune function of obese individuals can be reversed depends entirely on the effectiveness of weight loss. Immunity is the body's defense mechanism against viruses, bacteria, and toxins, and it is jointly carried out by macrophages that engulf foreign substances, T cells that attack these substances and form antibodies, and B cells. Ichiro Kono conducted a study comparing obese males before and after weight loss with those in the standard weight group. The results showed that the macrophages' ability to engulf foreign substances was 20% lower in the obese males, and their T cell function was 30% lower. However, after weight loss, the macrophages' phagocytic ability returned to the same level as the standard weight group, and the T cell function also returned to normal.
Improving the immune function of obese people can help prevent infections and strengthen their physique. The best way to do this is to lose weight or cure the disease.
12. Obesity and Smoking
Cigarettes contain nicotine, tar, and other toxic substances, including benzene compounds. Smoke entering the lungs can cause coughing, and in certain individuals, it can even lead to lung cancer. Smoke entering the stomach stimulates intestinal peristalsis, enhancing digestion; however, prolonged exposure to smoke can suppress appetite and cause weight loss.
Quitting smoking is generally a good thing, but for many former smokers, it presents new challenges. Research from the U.S. Centers for Disease Control and Prevention (CDC) shows that Americans gain weight after quitting smoking, with men gaining an average of 2.8 kg and women an average of 3.8 kg. Those over 55 years old who smoked more than 15 cigarettes a day are particularly prone to weight gain after quitting. Why is this? Researchers have found that there are indeed some emotional and behavioral reasons, including the habit of putting things in one's mouth. Nicotine in tobacco accelerates overall physiological functions, especially the frequency of food metabolism, even though smoking mostly occurs during leisure time. Excessive smoking often increases heart rate; smokers' average heart rate is 84 beats per minute, compared to 72 beats per minute for non-smokers. Once smoking stops, metabolism slows down, food is consumed more slowly, and weight gain occurs.
People who quit smoking often relapse into their nicotine cravings, and when various circumstances force them to quit, they often experience a sense of emptiness and crave sweets. This is because nicotine lowers insulin levels in the blood, thus reducing cravings for sweets. Without the effects of nicotine, insulin levels often rise, leading people to tend to eat more sweets.
So, can smoking be used to lose weight? Actually, no. The harm caused by smoking to the body is far greater than the harm caused by being overweight. A significant number of patients die from smoking-related diseases. Will Chinese people experience the same thing as Americans? Although we haven't conducted large-scale epidemiological surveys, we have found in clinical practice that many thin patients experience a significant improvement in facial radiance after quitting smoking, but their weight does not increase significantly. In some cases, weight gain is closely related to changes in dietary habits.
Thirteen, Obesity and Gender
Before answering this question, let's take a look at the results of a 1968 survey in London, England, on the differences in body weight and obesity rates between men and women.
Comparison of the percentage of obese men and women in different age groups (%)
Age: 25-29, Overweight by more than 10% (male): 32.8, Overweight by more than 10% (female): 21.0
30–39: 47.2, 32.5
40–49: 59.6, 52.6
50–59: 50.3, 64.4
60–69: 51.1, 59.6
From the table above, we can see that the number of obese people increases with age for both men and women, but the rate of increase is faster for women than for men, surpassing men after age 50. Comparing men and women, the obesity rate is higher for men under 50, but higher for women after age 50. Overall, however, the number of obese adults is not significantly different between men and women. Some statistical data in my country also reflect this pattern, but after age 40, the obesity rate for women exceeds that of men. This is likely related to my country's ethnicity, lifestyle, and cultural traditions. While there are some differences in the number of obese men and women across different age groups, the total number is relatively even.
XIV. Obesity and Occupation
Choosing a suitable career is a common aspiration, and engaging in a particular profession for a long period can have a certain impact on one's physique. So, what kind of professions tend to cause weight gain?
People with low physical exertion, regular work schedules, and indoor jobs are more prone to obesity, such as teachers, cooks, administrative staff, and workers in certain specialized occupations. Surveys have found that many people who sit all day have some degree of abdominal obesity. Cooks, due to daily exposure to aromatic odors and excessive consumption of high-energy foods, have an obesity rate as high as 60.4%. Among workers in food factories and breweries, the obesity rate is as high as 44.8% (compared to only 15.9% in other workplaces). More than half of the workers in a vermicelli factory in Beijing have a history of obesity, and one-third have a history of diabetes. Approximately 80% of people who sit in offices for long periods are mild to moderately obese. Research shows that the obesity rate is higher among mental laborers than manual laborers, and higher among urban residents than rural residents.
Section 2: Why the goal of weight loss is health
I. The concept of body weight
Body weight refers to the total weight of all parts of the human body, and it is affected by age, sex, race, genetics, diet, and geographical environment. Therefore, body weight is constantly changing, but remains relatively constant within a certain period. For a normal person, under certain circumstances, the amount of water obtained from food and water intake each day is roughly balanced with the amount excreted through sweat, urine, feces, and water lost through the respiratory tract. This does not significantly affect the stability of the body's internal physiological changes. Therefore, maintaining a certain weight level is essential for overall health.
People often say, "Why do I gain so much weight in winter?" The amount of clothing worn, the protective accumulation of fat, and differences in measurement methods often lead to a feeling of being thin in summer and strong in winter. However, accurate measurement isn't difficult. Simply stand on a medical scale, follow your doctor's instructions, remove heavy clothing, wear only minimal underwear, and measure at a fixed time (mostly in the morning), after urinating or before eating. Weight measured this way is relatively accurate. If you can't eliminate as many variable factors as possible, you'll wonder why you often experience unexplained weight gain or loss. However, sudden weight loss or persistent weight gain often indicates the presence of illness.
II. Standard weight and its measurement methods
People vary in weight; being underweight is considered thin, and being overweight is considered obese. So, what standard is used to measure whether someone is thin or fat? This requires a reference value, which we call standard weight. Currently, there is no unified standard weight data in my country. Two commonly used calculation methods are:
One is:
Adult's ideal weight (kg) is calculated as: [Height (cm) - 100] × 0.9
Another one is:
Male height (cm) - 100 = Standard weight (kg)
Female height (cm) - 100 = Standard weight (kg)
The two calculation methods mentioned above have been widely adopted.
In addition, the Academy of Military Sciences has also introduced a method for calculating the ideal weight for Chinese people:
Ideal weight for Northerners = [height (cm) - 150] × 0.6 + 50 (kg) Ideal weight for Southerners = [height (cm) - 150] × 0.6 + 48 (kg) This calculation method seems to be more suitable for Chinese people in both the North and South.
A simple method for calculating a child's standard weight is:
1-6 months: Birth weight (kg) + age in months × 0.6 = Standard weight (kg)
7–12 months: Birth weight (kg) + age in months × 0.5 = Standard weight (kg)
For children over 1 year old: 8 + age × 2 = ideal weight (kg)
However, because a person's weight is related to many factors, there are differences between individuals, and it can vary throughout the day. Furthermore, geographical location (due to gravity), season, climate, and individual circumstances also have an impact on weight, making it difficult to perfectly conform to the ideal weight. In other words, it's difficult to represent it with a constant value; rather, it should be a numerical range, which we call the normal value, generally within ±10% of the ideal weight. Exceeding this range is considered abnormal weight.
III. Methods for determining obesity
Obesity, besides being judged by the percentage of overweight, must also consider other factors. Weight gain isn't solely caused by increased adipose tissue. For example, athletes (especially bodybuilders) with well-developed muscles, or patients with severe edema, may have weight exceeding the normal range but are not necessarily obese. Conversely, those who are not overweight are not necessarily not obese. Due to a sedentary lifestyle and lack of exercise, energy is not burned, fat accumulates in the body, muscle mass decreases, and functional cells are reduced, with muscle tissue being replaced by adipose and connective tissue. However, because their body fat exceeds the normal range, they are still considered obese. Another type is localized fat accumulation, such as a "large belly," which, even if the weight is not more than 20% above the standard weight, can be called "abdominal obesity." Therefore, many countries, such as the United States and Japan, currently assess the degree of obesity based on subcutaneous fat thickness or the proportion of adipose tissue in total weight. However, these methods are relatively cumbersome, and the appearance of obese individuals is quite obvious, so this method is not yet widely used. Currently, height, weight, and subcutaneous fat thickness are still widely used to estimate obesity.