A Scientific Explanation of Human Obesity: Causes and Measurement Standards
Section 2: A Scientific Explanation of Human Obesity
Why is weight control so important for a person's entire life? Generally speaking, obese people are prone to diseases such as diabetes, atherosclerosis, hypertension, coronary heart disease, poor respiratory ventilation, stroke, and gallstones. They also have a lower stress response to various stressors, making it difficult to adapt to sudden environmental changes and resist various infections. Medical research has confirmed that obesity is very harmful to a person's physical and mental health and also affects their physical appearance. So, how should we control our weight? First, we should understand some basic knowledge: How much energy should we consume each day, and how should we consume it? How much energy should we reduce each week without affecting our health and work? Why do we feel hungry today but not yesterday, even with the same food intake? In other words, to lose body fat, we must first understand our energy consumption range, which is generally determined by a person's age, gender, weight, and occupation.
1. Causes of obesity
Congenital obesity: mainly determined by genetic factors.
Secondary obesity: Obesity is usually caused by certain diseases.
Simple obesity: This falls under the physiological category and involves many factors, including both genetic and environmental factors.
An imbalance between diet and exercise: This is a major cause of obesity.
Age factor: As we age, our metabolic rate decreases, and our calorie needs gradually reduce. Generally speaking, women need about 5,000 fewer calories per year of age, while men need about 7,000 fewer calories per year of age. If your food intake remains the same, the excess calories will be stored. After the age of thirty, not only does weight become increasingly difficult to control, but fat tends to accumulate in the abdomen and hips. Women often develop a pear-shaped figure, while men tend to have an apple-shaped figure. Maintaining a good figure at this age requires not only restricting your diet but also consistent exercise to prevent excessive fat accumulation in the abdomen and hips.
Psychological Factors: Research shows that many social and environmental factors can affect a person's psychology, thus leading to obesity. For example, some people try to compensate for stress and unhappiness in life or work by indulging in the pleasures of food, resulting in gradual obesity. There are many such examples in daily life. Therefore, psychological tranquility, imbalance, mental trauma, and emotional fluctuations are all important factors contributing to obesity; the saying "a carefree mind and a worried mind both lead to obesity" illustrates this point. The Key to Weight Loss: In today's society, due to improved living standards, lack of exercise, and improper diet leading to calorie imbalance, obesity is currently the most common cause of obesity. Therefore, controlling calorie balance and ensuring proper energy intake are key to weight loss.
2. The critical stage when women are most prone to gaining weight
Several medical studies from various American universities, presented at the North American Obesity Research Association conference, all indicate that women are most susceptible to obesity during three distinct phases. Adolescent girls are particularly prone to obesity, with the earlier a girl's menstruation begins, the higher her chances. A five-year study presented at the conference by the University of Alabama showed that women who had given birth gained 20 pounds over five years, while women who had not given birth gained only 11 pounds. American experts point out that women are most prone to obesity during three phases of their lives: puberty, pregnancy, and post-menopause, due to hormonal changes affecting fat accumulation. The earlier a woman's menstruation begins, the earlier her estrogen and progesterone levels rise, making her more susceptible to obesity if she consumes excessive calories. Pregnant women have higher levels of sex hormones and tend to eat more during pregnancy to ensure the fetus receives sufficient nutrients, making weight gain during pregnancy easy. After menopause, women experience lower hormone levels and a slower metabolism, making it easier to accumulate fat, which shifts from being concentrated in the breasts and hips in youth to accumulating in the abdomen. Experts say that teenage girls and postpartum women should not lose weight by dieting, but should instead exercise more. Postmenopausal women should pay attention to their diet and reduce their intake of high-fat foods.
Puberty: Weight gain is caused by increased estrogen and luteinizing hormone levels, which increase the chances of fat accumulation, leading to fat buildup throughout the body. Remedy: Increase exercise to burn calories.
Weight gain during pregnancy is caused by increased sex hormones and increased appetite. The remedy is to exercise more to burn calories.
Menopause: Weight gain is caused by low levels of sex hormones and a slowed metabolism, leading to fat accumulation in the abdomen. Remedies include increasing exercise and reducing the intake of high-fat and high-calorie foods.
3. What are the standards for measuring obesity?
Overweight: refers to a person's weight being greater than the standard weight.
Being overweight: This refers to a body fat percentage exceeding 20% of body weight for men and 25% for women. The ideal body fat to body weight ratio is 13-17% for men and 18-22% for women.
Does being overweight or overweight equate to obesity? Many people would answer "obesity." However, this answer is incorrect. Being overweight or overweight does not necessarily mean obesity. There are two reasons for being overweight: muscle mass and excess body fat. If being overweight is due to fat accumulation, then it is obesity. But if being overweight is due to muscle mass, it cannot be considered obesity. Therefore, we cannot use weight as the sole criterion for measuring obesity; rather, we should use the amount of body fat as the standard.
Methods for assessing height and ideal weight: Obesity level = (actual weight - ideal weight) / ideal weight; Obesity level ±10% is healthy, 15-20% is normal, greater than 20% is obese, 20-30% is grade 1 obesity, 30-50% is grade 2 obesity, and 50-100% is grade 3 obesity.
4. Methods for measuring obesity
Underwater sebum measurement: The underwater sebum measurement method is based on Archimedes' principle to measure body density and fat percentage.
Electronic impedance meter: unstable, complex, and expensive.
Ultrasonic and infrared instruments: Unstable, complex, and expensive.
Height-Ideal Weight Chart (HE HT): Not suitable for athletes or those with a high muscle mass. Specific standards are as follows: People under 165 cm: Ideal weight = Height (cm) - 100 (kg); People 166-175 cm: Ideal weight = Height (cm) - 105 (kg); People over 176 cm: Ideal weight = Height (cm) - 110 (kg).
Body Mass Index (BMI): BMI = weight (kg) to the square of height. BMI < 20 is underweight; BMI = 20-24 is underweight; BMI = 24-26.5 is normal; BMI > 26.5 is overweight; BMI > 30 is obese.
The Waist-Hip Index (WHI) is the ratio of waist circumference to hip circumference. It can be helpful in predicting abdominal distension or cardiovascular disease. For men, a WHI < 0.85 indicates a fit or lean physique, WHI = 0.85-0.9 indicates a normal physique, and WHI > 0.9 indicates obesity. For women, a WHI < 0.75 indicates a fit or lean physique, WHI = 0.75-0.8 indicates a normal physique, and WHI > 0.8 indicates obesity.
5. Energy balance and weight control
A healthy and efficient weight loss rate: Studies have shown that a weight loss of no more than 0.5-1 kg per week is ideal. This is because excessively rapid weight loss is not only unhealthy but can also be highly dangerous, such as causing ketoacidosis, and has a relatively high rate of weight regain. One kilogram of body fat equals 7000 kilocalories, so daily calorie expenditure should not exceed 1000 kilocalories consumed.
Basal metabolism: Energy metabolism in a person under the following conditions: awake, resting, fasting, and at around 20 degrees Celsius. A 60-kilogram person consumes approximately 60 kilocalories per hour.
Basal metabolic rate (BMR): This refers to the minimum amount of energy required to maintain basic life functions per unit of time; this energy consumption is relatively constant. Unit: kcal/kg/hour.
Scientific exercise principles include: gradual progression, systematic exercise, comprehensive exercise, overload, and individual differences.
Weight control: The principle of weight control is that when calories are balanced, weight remains constant; when calories are imbalanced, weight increases or decreases.