What Are Some Common Myths About Body Fat?
Whether it is in the gym or the medical examination center, there is a body fat test. Many businesses also aim at our thirst for health and have launched instruments that can measure body fat percentage. The question is, are these instruments reliable?
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| Figure from cdp |
Myth 1: The lower the body fat rate, the better
Mistake.
The so-called body fat percentage is the ratio of body fat weight to total body weight.
Ideally, daily energy intake and energy expenditure should be roughly balanced. If too much energy is taken in or too little energy is expended, a "surplus" occurs, which is converted by the body into fat and stored.
Some friends shake their heads when they hear "fat", but it's not necessary. Fat is one of the essential tissues of the human body and has important physiological functions: maintaining body temperature when it is cold, reducing tissue friction when exercising, providing energy when hungry, and secreting hormones to maintain normal physiological metabolism.
Fat is not a monolith. Generally speaking, excess energy is first sent to the subcutaneous, where it becomes subcutaneous fat. Although subcutaneous fat may look unsightly, its health effects are minimal. However, the space under the skin is limited. If there is not enough space, the body will send energy between the internal organs and convert it into visceral fat. Visceral fat has a great impact on health and is the driving force behind diabetes and cardiovascular disease.
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| Figure from unsplash |
The accumulation of visceral fat can produce significant body shape changes. The whole person looks like a pear, and doctors call it abdominal obesity.
So, how do you know if there is fat accumulation in your internal organs?
According to the recommendations of the American Council on Exercise (ACE), it is normal for men to have a body fat rate of less than 25%. Women should be special. As mentioned earlier, fat can secrete hormones, which is of great significance for maintaining a normal menstrual cycle. The normal range for fat percentage is between 25% and 31%.
In addition, body fat percentage changes with age. Generally speaking, the older you are, the higher the body fat percentage. You must make a reasonable judgment based on your own situation, and don’t blindly pursue a low body fat rate.
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| The relationship between body fat percentage and age Figure from CDC |
Myth 2: The measurement results of the body fat meter are accurate
Depends on the situation.
There are many ways to measure body fat percentage. Such as dual energy X-ray absorption (DEXA), weighing in water. The former uses the characteristics of X-rays. The higher the density of the target, the stronger the attenuation of X-rays, and the distribution of fat is evaluated; the latter uses the principle of buoyancy. Under the same mass, the density of fat is smaller than that of muscles and bones, so Larger and more buoyant. Both schemes are very accurate, but unfortunately the instruments are expensive and cumbersome to operate.
The most common test method at present is the bioimpedance method (BIA). Muscle tissue has a relatively high water content and thus has a low electrical resistance, whereas adipose tissue has less water and a high electrical resistance. Therefore, as long as the relationship between the resistance and the body fat rate is found, a little current is applied to the subject, and the resistance is measured, and the body fat rate can be estimated.
Common body fat meters often have several very shiny round buttons, which are electrodes.
The advantages of the resistance measurement method are that the operation is simple, the instrument is cheap, and one can be bought for a hundred dollars. The disadvantages are also obvious - first, the relationship between resistance and body fat rate needs to be established in advance. According to the assessment of the Chinese Center for Disease Control and Prevention, different databases and different algorithms are very different; secondly, any factors that can affect the body's resistance will affect the measurement results. When the temperature is low, the resistance will increase; if there is water on the feet, the resistance will decrease; drinking water and eating will increase the water content in the body; sweating during running will reduce the water content in the body...
Therefore, the measurement results of common body fat meters can only be used as a reference, and it is best to control the measurement conditions, such as measuring before eating every time.
Is There An Easier Solution?
Have.
First, it can be assessed using body mass index and waist circumference. The calculation of body mass index is very simple, first weigh the weight in kilograms, then measure the height, calculate its square, in meters, divide the former by the latter, and the normal range is between 18.5 and 25. Waist circumference is simpler, less than 85 cm for men and less than 80 cm for women is normal. Both are normal, nothing to worry about.
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| Figure from pexels |
Second, in recent years, some scholars have proposed the concept of relative fat mass (RFM), which uses height and waist circumference to estimate body fat percentage. The calculation results have a good correspondence with the measurement results of DEXA.
Myth 3: As long as you eat XX food or medicine, you can quickly reduce body fat
Never try.
The general principle of reducing body fat is to improve your lifestyle.
In terms of food, it is necessary to be sufficient and diverse. The daily energy intake should not be less than 1600 kcal, otherwise it will affect your health; eat more vegetables and fruits, and less red meat and rice - if you really want to eat rice, you can freeze it after steaming. Studies have shown that frozen rice has an increase in resistant starch and a greater sense of satiety.
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| Figure from unsplash |
In terms of exercise, start with the exercise method you are familiar with and slowly increase the amount of exercise. There are rumors that you have to exercise for more than a few minutes to burn fat, but that's not true. Don't blindly ask for more, lest your body be overwhelmed. Don't underestimate the effect of daily exercise. Walking briskly for half an hour every day is very good for your health.
If you are doing well in both aspects, but your weight has not dropped, or even affects your health, you can seek professional help, use some drugs or improve your weight through surgery.
It's important to remember: there are no foods that can quickly lose fat, and there are no drugs that can quickly lose fat.
In fact, every method of treating obesity has a strict scope of application. It is not possible to use it if you want. The fast weight loss pills circulating on the market are either ineffective or contain contraband, which may be life-threatening in serious cases.
References
1. Dehghan, Mahshid, and Anwar T. Merchant. “Is Bioelectrical Impedance Accurate for Use in Large Epidemiological Studies?” Nutrition Journal, vol. 7, Sept. 2008, p. 26. PubMed, doi:10.1186/1475-2891- 7-26.
2. Goossens, Gijs H. “The Metabolic Phenotype in Obesity: Fat Mass, Body Fat Distribution, and Adipose Tissue Function.” Obesity Facts, vol. 10, no. 3, 2017, pp. 207–15. PubMed, doi: 10.1159/000471488.
3. Woolcott, Orison O., and Richard N. Bergman. “Relative Fat Mass (RFM) as a New Estimator of Whole-Body Fat Percentage ─ A Cross-Sectional Study in American Adult Individuals.” Scientific Reports, vol. 8, no. 1, July 2018, p. 10980. PubMed, doi:10.1038/s41598-018-29362-1