Southerners vs Northerners, who is fatter? The truth is...

People in the south are thinner than people in the north. Is this an illusion?

Really not.

In 2017, the "Chronic Disease and Risk Factor Monitoring Data" released by the Chinese Center for Disease Control and Prevention showed that the obesity rate in the north is significantly higher than that in the south. In terms of overweight rates, the overweight level in most northern provinces is also higher than that in the south.

Image source: @People's Daily

01

How to determine whether you are obese?

Many people judge whether they are fat or not by looking in the mirror to see their body shape or pinching their belly to see if there is fat. In fact, these methods are not accurate.

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Currently, the internationally commonly used standard for measuring whether a person is overweight, obese, or healthy is the body mass index (BMI), which is also called body mass index or weight index.

The calculation formula for BMI is BMI = weight (kg) ÷ height² (m) , which is your weight divided by the square of your height.

Image source: Dietary Guidelines for Chinese Residents (2022)

According to the calculated values, a BMI between 18.5-24.0 is a healthy weight.

If the BMI is between 24.0-28.0, it is "overweight"; if the BMI is greater than 28.0, it means "obese".

Some people may look a little fat, feel fat when pinching their belly, or feel fat, but they are not necessarily really obese.

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However, we need to remind everyone that among people with overweight BMI, the heavier the weight, the greater the chance of developing obesity. If you are overweight, you should start to pay attention to control.

02

Factors that affect body weight

Why is this the case? What factors influence obesity?

1. Genes

Our weight is influenced by genetic factors.

This is actually very easy to see in life. For example, if you see a family, if the parents are fat, usually the children will also be fat. This is genetic inheritance.

2. Metabolism

Metabolism refers to the chemical processes that occur in the body that are necessary to maintain life.

Different people have different metabolisms, which also affect their weight. For example, the basal metabolic rate of the body. Some people have a high basal metabolic rate. They eat the same food and do the same work as you, but they consume hundreds of calories more than you. So you are more likely to gain weight, but he is not.

In animals, we often use feed conversion rate to evaluate the efficiency of animal food conversion. In fact, humans also have a similar effect. Some people have a high food energy conversion rate. For example, if you eat the same food, you convert more energy into energy and store it in your body than others, and you are more likely to gain weight.

3. Age

As we age, our body composition and basal metabolism will change. For example, the body's energy metabolism rate will decrease, and physical activity will decrease, which will also affect our weight.

4. Disease

Some diseases can also affect weight changes, such as anorexia nervosa, chronic hepatitis, cirrhosis, and cancer, which can cause weight loss.

5. Diet

If we eat too much, especially high-fat, high-sugar, high-energy foods such as fried chicken, French fries, etc., the excess energy will cause us to gain weight.

6. Physical activity

Physical activity, such as running, brisk walking, and even doing housework, consumes energy in the body. But if physical activity decreases, the energy consumption is too low and weight can increase.

03

Why are people in the north fatter than people in the south?

According to the "Chronic Disease and Risk Factor Monitoring Data", the top five provinces in my country with the highest obesity rates are:

First Beijing 25.9

Second Hebei 22.2

Third Xinjiang 21.5

Fourth Tianjin 21.2

Fifth Heilongjiang 19.8

They are basically northern provinces.

The provinces with the lowest obesity rates are Guangxi, Hainan, Tibet, Guizhou, and Sichuan, which are basically in the southwest region. Therefore, it is not an illusion that people in the south are thinner than people in the north, but an objective fact.

Why? What are the differences between people in the north and south?

1.Different dietary structure

People in the north eat more noodles, while people in the south eat more rice.

Although they are all carbohydrates, the cruel reality is that people who eat pasta are indeed more likely to gain weight.

A study conducted by Xi'an Jiaotong University investigated and analyzed more than 100,000 middle-aged and elderly people in Northwest my country and found that people who like to eat noodles have a higher risk of obesity than those who like to eat rice. This is especially true for men.

Data analysis found that replacing wheat with rice of the same frequency and weight (5 times a week) was significantly associated with a 36.5% reduction in the risk of excess body fat in normal-weight men and a 20.5% reduction in the risk of central obesity in normal-weight women.

Why?

On the one hand, wheat protein and rice protein have different effects on metabolism. In addition to carbohydrates, wheat and rice also contain a small amount of protein, and the effects of these proteins on fat metabolism are different.

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Wheat is mainly gluten protein, and some studies have shown that gluten protein may promote weight gain by reducing tissue heat production and energy consumption, while rice protein may inhibit fat synthesis and increase fat decomposition.

On the other hand, the energy density of pasta and rice is also different.

Rice can absorb more water, so it has a higher water content. Compared with other foods of the same weight, the calories in rice are lower. However, the water content in steamed buns and flower rolls is only about 45%-50%, and pancakes are even lower. They have less water and higher calorie density, so if you eat a little more, you will consume a lot more calories.

2. Different climate

As we all know, the temperature in the north is generally lower and colder, which may also contribute to obesity.

The weather in the north gets cold earlier and stays colder for longer. In the extremely cold Heilongjiang, the winter can even last for about half a year.

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When the weather is cold, our bodies will instinctively store more heat , and we are more willing to eat hot, high-calorie foods to resist the cold. This is why there is a tradition of "putting on weight in autumn".

In addition, when the weather is cold, people's opportunities to exercise outdoors will be greatly reduced, and they will stay at home most of the time, forced to eat more and move less, which will naturally make them more likely to gain weight. In the south, the temperature is usually high, the body's energy metabolism is faster, and people can exercise outdoors more and longer throughout the year, so it is naturally less likely to gain weight.

References:

[1]Dietary Guidelines for Chinese Residents (2022)

[2] Chronic Disease and Risk Factor Surveillance Data

[3] Xu K, Zhang B, Liu Y, Mi B, Wang Y, Shen Y, Shi G, Dang S, Liu X, Yan H. Staple Food Preference and Obesity Phenotypes: The Regional Ethnic Cohort Study in Northwest China. Nutrients. 2022 Dec 9;14(24):5243. doi: 10.3390/nu14245243. PMID: 36558402; PMCID: PMC9784345.

[4] Santos, SH; et al. Wheat gluten intake increases weight gain and adiposity associated with reduced thermogenesis and energy expenditure in an animal model of obesity. Int. J. Obes. 2016, 40, 479–486.

[5] Yang, Lin et al. “Rice protein improves adiposity, body weight and reduces lipids level in rats through modification of triglyceride metabolism.” Lipids in health and disease vol. 11 24. 13 Feb. 2012, doi:10.1186/1476-511X-11-24

[6] Luan Hui, Yang Lin. Research progress on the regulation of cholesterol metabolism by rice protein[J]. Food Industry Science and Technology, 2012, 33(5):4.

Author: Ruan Guangfeng, Director of the Science and Technology Department of the Kexin Food and Nutrition Information Exchange Center

Reviewer: Zhu Huilian, Professor and Director of the Department of Nutrition, School of Public Health, Sun Yat-sen University