People with a normal Body Mass Index (BMI) may have abnormal body composition or other health indicators such as blood cholesterol, triglycerides, blood sugar, or bone density.
Misconception 1: If you are not overweight or underweight, you don't need to exercise.
Assessing whether one is overweight or underweight should be based on the Body Mass Index (BMI) or the difference between one's actual weight and the standard weight for their height.
People with a normal Body Mass Index (BMI) may have abnormal body composition or other health indicators such as blood cholesterol, triglycerides, blood sugar, or bone density.
Abnormal body composition means an improper proportion of body fat. Some women may appear slim, but their body fat percentage is still high when measured. A high body fat percentage includes two aspects: a high absolute amount of fat, and a low amount of muscle mass, leading to a relatively high fat content. Slim women often fall into the latter category. This condition is mainly caused by insufficient exercise and a gradual decrease in muscle fibers after middle age.
For individuals with a normal BMI, exercise can alter body composition and the muscle-to-fat ratio, and improve the body's overall functions.
Misconception 2: Eggs contain a lot of cholesterol, so they are not suitable for middle-aged and older people.
High blood cholesterol is a risk factor for atherosclerosis. People are well-aware of this, but they often lack an understanding that cholesterol is an essential substance for human survival, leading to various misconceptions.
The human body experiences a large number of cell deaths and new cell growth every day. For example, red blood cells in the blood are updated at a rate of 0.8% daily. The cell membranes of these new red cells require a certain amount of cholesterol. Cholesterol is also a primary raw material for synthesizing adrenaline and sex hormones, and it participates in the synthesis of vitamin D. Therefore, cholesterol has very important physiological functions.
Under normal circumstances, there is no need to overly restrict the amount of cholesterol in the diet. Currently, it is widely believed in China and abroad that for healthy individuals, the daily intake of cholesterol should not exceed 300 mg. For people with high low-density lipoprotein (LDL) and those with diabetes or cardiovascular diseases, the daily intake should not exceed 200 mg.
Although eggs contain a relatively high amount of cholesterol, they also contain many essential nutrients for the human body. It is recommended that healthy people eat one egg per day. For individuals with high LDL, or those with diabetes or cardiovascular diseases, eating one egg every two days is more appropriate.
Misconception 3: Fruits are snacks, so they are optional.
Fruits contain minerals that the human body needs but cannot synthesize on its own, have strong antioxidant properties, contain vitamins that prevent cell aging, and include soluble fiber—pectin—that can significantly lower blood cholesterol levels, making them very beneficial to human health. However, the proportion of Chinese people, especially men, who regularly eat fruit is very low.
An analysis of data from a 10-year follow-up study of one million people in the United States in the 1980s found that in the group who rarely or never ate fruit, the mortality rate from lung cancer was 1.75 times higher than that of the group who regularly ate fruit. What component in fruit is responsible for this effect? Is it vitamins? Can commercially available vitamin supplements have the same effect? A further analysis of the relationship between lung cancer mortality and the use of vitamin supplements found that regular vitamin supplementation did not provide similar protective effects.
According to experts in nutritional immunology, the explanation for this is that vitamins in natural plants do not work in isolation but in conjunction with other vitamins and nutrients. Because chemically synthesized vitamins are separated from other vitamins and nutrients, and the proportions of the components in the compound are different from those in natural sources, they cannot produce the same effects as natural vitamins.
Therefore, in daily life, fruits should be an essential part of the daily diet and are by no means optional. For the general population, vitamin supplements should absolutely not, and cannot, replace the daily need for fruits and vegetables.