What you think is “fat” may not be fat, and what you think is “not fat” may be really fat…

Today is United Nations Diabetes Day. It is well known that overweight and obese people are more likely to develop diabetes than people of normal weight.

Not long ago, a "plus-size" passenger who was stuck in a high-speed rail seat became a hot topic... To be honest, obesity not only puts a burden on your health, but also brings inconvenience to your life.

This year's World Obesity Atlas shows that if we continue our current lifestyle, by 2035, 4 billion of the world's 8 billion people will be obese.

Someone said: I am so fat.

Some people say: I’m not fat.

In fact, what you think is fat may not be really fat, and what you think is not fat may be really fat...

01 Obesity and BMI

The World Health Organization believes that whether a person is obese depends on his body mass index (BMI). my country has adjusted this definition based on the situation of its own residents. Residents with a BMI ≥ 24 are overweight, and BMI ≥ 28 are obese.

BMI (Source: Produced by Zhai Guoqing)

Many sellers of fitness science and weight loss products often mention BMI as a sign of their professionalism. In fact, BMI is not a medical parameter .

Adolf Ketterer, who proposed BMI, was a mathematician who applied statistical methods to sociology and population management. In order to help the insurance industry measure the health status of insured persons and use it for simple risk assessment, he proposed BMI - the relationship between height and weight.

Because this formula is simple and easy to use, it suits most people's situations, and some people have indeed found that the larger the BMI, the greater the possibility of suffering from certain diseases. Therefore, more and more people use BMI, and later even the World Health Organization used it.

02 Just because you say you are fat doesn’t necessarily mean you are really fat!

Whether a person is fat or not depends on the ratio of body fat to body weight . Strictly speaking, BMI is not a medical index, it is affected by muscles and bones , and as an average, it cannot fully reflect the situation of everyone .

For example, an athlete of the same height may weigh more and have a higher BMI, but this does not mean that the athlete is overweight or unhealthy.

Source: Tuchong Creative

Therefore, in order to more accurately measure an individual's obesity, that is, the amount of fat in the body, scientists have found other methods.

At present, the most widely recognized method for measuring body fat is dual-energy X-ray absorptiometry, or DEXA for short . This method is known as the gold standard for measuring body fat. Since fat, minerals, and other tissues in the human body absorb light differently , two different energies of X-rays can be sent to the human body to scan the whole body to estimate your body composition. Finally, divide the fat weight by the body weight to get your body fat percentage, and then compare it with the body fat percentage distribution table to determine whether you are obese.

Dual-energy X-ray absorptiometry (Source: Wikipedia)

However, professional methods are more expensive . Ordinary people can also make rough measurements through simple methods such as waist-to-hip ratio and electronic fat scales .

03 Why am I the fat one?

The current mainstream view is that for ordinary people (obesity caused by genetics and diseases is not included), when the energy intake of humans is greater than the energy consumed, the energy is stored in the body and converted into fat, which will cause obesity. The energy intake of people mainly comes from carbohydrates/lipids. If a large amount of either type is consumed, the part that cannot be consumed will be converted into fat.

Not only humans, but other primates also gain weight for this reason. For example, Kazi, the first chimpanzee proven to understand English, became three times the average weight of the group and was eventually forced to lose weight.

Chimpanzee Kazi can understand words, but is forced to lose weight due to obesity (Source: Wikipedia)

In September 2021, Dr. David Ludwig published an article titled "The carbohydrate-insulin model: a physiological perspective on the obesity pandemic" in The American Journal of Clinical Nutrition, proposing a new viewpoint, namely the carbohydrate-insulin model - highly processed carbohydrates contain a lot of sugar and can quickly increase blood sugar. Therefore, when we consume them, it will cause the body to produce a stress response , increase insulin secretion, and fat cells begin to store energy , which in turn makes the brain mistakenly believe that the body does not get enough energy, so it will reduce the metabolic rate to save energy, and at the same time make us feel hungry, so we will eat more and more.

Source: Tuchong Creative

This statement provides a new approach to finding the causes of obesity - we should not only pay attention to how much we eat, but also what we eat .

04 More than 90 years ago, the obesity rate had already shown signs of rising

Some people may think that human obesity is a phenomenon of the past two or three decades. However, the latest research shows that the human obesity rate has been on the rise since 1930. This study found that those with a low BMI index have basically not changed in the decades of research, while those with a high BMI index have shown a clear upward trend.

However, a major limitation of this study is that its sample does not include middle-aged people, who are the majority of people with obesity. Nevertheless, this study still gives us new inspiration: perhaps there are other reasons for obesity. Scientists explain this by genetics or changes in carbohydrate supply .

Nowadays, more and more people recognize that excessive obesity is a chronic metabolic disease and should be treated professionally.

Healthy people do not need to lose fat excessively. Fat is an essential substance for the human body. It can protect the body, provide energy, and keep the body warm, so the less the better.

For most people, a balanced diet and adequate exercise are the magic bullet for weight control.

References:

[1]Pan XF, Wang L, Pan A. Epidemiology and determinants of obesity in China. The Lancet Diabetes & Endocrinology. 2021;9(6):373-392. doi:10.1016/S2213-8587(21)00045-0

[2]The origins of the obesity epidemic may be further back than we thought. Retrieved March 6, 2023 from https://www.science.org/content/article/origins-obesity-epidemic-may-be-further-back-we-thought

[3]World Obesity Atlas 2023. Retrieved September 22, 2023 from https://s3-eu-west-1.amazonaws.com/wof-files/World_Obesity_Atlas_2023_Report.pdf

[4]Nutrition transition and related health challenges over decades in China. Eur J Clin Nutr. 2021;75(2):247-252.

[5]https://jandan.net/p/114117#/

[6]https://www.who.int/health-topics/obesity#tab=tab_1

[7] David Ludwig, The carbohydrate-insulin model: a physiological perspective on the obesity pandemic. The American Journal of Clinical Nutrition. https://academic.oup.com/ajcn/advance-article/doi/10.1093/ajcn/nqab270/6369073

[8] https://zhuanlan.zhihu.com/p/92301089

[9]https://www.cn-healthcare.com/articlewm/20210915/content-1264241.html

Author: Jiuyi Popular Science Creator

Reviewer: Tian Weina, Associate Professor of Beijing Institute of Food Science and Registered Nutritionist of Chinese Nutrition Society

Produced by: Science Popularization China

Produced by: China Science and Technology Press Co., Ltd., China Science and Technology Publishing House (Beijing) Digital Media Co., Ltd.