Saving obesity may depend on me! Here is the "confession" of beige fat cells

Hello everyone, my name is "beige fat cells". Haven't heard of me? No problem! Today is a good opportunity for you to get to know me. Before I start introducing myself, let me first give you a brief introduction to white fat cells and brown fat cells. Although their names are only one letter different, they are completely different in appearance and function.

Obesity's helper: white fat cells

The fat droplets in white fat cells are very domineering, occupying more than 90% of the volume of the entire cell. Other organelles can only be squeezed into a very small area. Even the cell nucleus is squeezed into a small "half-moon shape", completely lacking the majestic appearance it has in other cells.

White fat cells are mostly found in the subcutaneous and around the internal organs in the abdomen, buttocks, thighs, etc. Their main function is to store energy and provide shock absorption for the internal organs.

The "fat" we usually talk about actually refers to white fat cells. Every adult has about 30 billion white fat cells in their body, and the size of white fat cells determines whether a person is obese or not.

White fat cells are not just a source of fat storage. Excessive white fat cells wrapped around the internal organs are also the culprits of various cardiovascular diseases, diabetes and other diseases. Lipotoxicity can be eliminated through the nutrient storage function of white fat cells, but when excess calories exceed the storage capacity of white fat cells, white fat cells will malfunction, leading to insulin resistance and dyslipidemia. Metabolic disorders of white adipose tissue are the key pathological phenomena leading to metabolic syndrome.

Burn Your Calories – Brown Fat Cells

Brown fat cells are different. They have small lipid droplets and many mitochondria. Mitochondria are the overlords in brown adipose tissue and play a vital role.

Brown fat cells are mainly found in the shoulder blades and chest. Under cold or other stimuli, the "dominant" mitochondria in brown fat cells will command the uncoupling protein-1 living in it to play a role, coupling mitochondrial respiration and ATP synthesis, and converting the electrochemical gradient of transmembrane protons into heat energy, generating heat and burning fat.

It sounds like brown fat cells are a major contributor to weight loss. Unfortunately, although the content of brown fat cells in infants and young children is very high, accounting for 5% of their body weight, the number of brown fat cells will gradually decrease with age. For a long time, the scientific community even believed that there were no brown fat cells in adults. Thanks to the rapid development of imaging technology, scientists gradually realized that it is not that brown fat cells do not exist in adults, but that there are too few of them, and weight loss cannot be relied on.

New idea for weight loss: beige fat cells

At this moment, I - a beige fat cell, make my debut!

I am homologous to white fat cells, both of which are differentiated from Myf5-negative progenitor cells. It is worth noting that under certain conditions such as exercise or cold, the lipid droplets of some white fat cells will become smaller, the mitochondria will become more, and they will gradually approach brown fat cells and eventually turn into beige fat cells. This process is called browning of white adipose tissue by scientists.

"Brownization" is not a permanent change. When the inducing factors are lost, I will also transform from beige fat cells to white fat cells again.

The good news is that I am not just a cell with nothing on the outside. I look similar to brown fat cells, and I am similar inside! In the human body, I play a similar role to brown fat cells: increasing energy consumption by producing heat without shivering.

What’s even more amazing is that, according to scientists’ latest research, I have a stronger ability to stimulate heat production than brown fat cells, my expression of uncoupling protein-1 is stronger, so my uncoupled breathing exercise will also be stronger.

Activating cells - a way to lose weight

So how do I get activated?

1. Exercise. During exercise, muscle cells produce an active substance, irisin, which further induces the "browning" of white fat cells. Irisin does not seem to have any effect on the activation of brown fat cells, but only affects the "browning" process.

2. Cold stimulation. Studies have shown that after cold stimulation, the sympathetic nerves release norepinephrine, which binds to the adrenergic receptors on the surface of the fibroblast reticular cells of the inguinal lymph nodes to promote the secretion of interleukin 33. Interleukin 33 acts on the subcutaneous fat tissue and promotes the "browning" process of white fat cells.

In addition, there are many inducing factors, such as catecholamines and capsaicin, which are related to the formation of beige fat cells. However, the specific mechanism has not yet been clarified, and most of them require repeated stimulation and harsh external conditions. It is impossible to reproduce a clearer activation pathway in the human body. The research on activating beige fat cells for weight loss still has a long way to go.

Obesity is not far away - the data speaks for itself

According to the "Report on the Nutrition and Chronic Disease Status of Chinese Residents (2020)", more than half of the adults in my country are overweight/obese, and the overweight/obesity rates of children and adolescents aged 6 to 17 and under 6 are 19.0% and 10.4% respectively.

Obesity can cause a higher risk of early death and increase the overall mortality rate. It is also closely related to the occurrence of various chronic diseases and tumors.

Not only that, obesity also brings high medical expenses. Clinical data show that obesity is significantly positively correlated with personal annual medical expenses. In addition to increasing direct medical costs by 31.8%, it will also increase indirect burdens by 61.8% (specifically referring to the opportunity cost losses caused by obesity, including decreased ability to carry out daily activities, loss of work productivity, reduced working hours and lower family income).

Controlling your weight is urgent!

There is no trick to lose weight - the balance between eating and moving is very important

In essence, obesity is caused by energy intake exceeding energy consumption, which leads to abnormal fat accumulation. Simply controlling diet or exercising alone cannot really improve our physical condition. The first point of controlling weight is to balance eating and moving.

In other words, controlling dietary energy intake allows white fat cells to function normally without exceeding their capacity, and exercise activates the heat production function of beige fat cells and brown fat cells, increasing energy consumption. The combination of the two can achieve twice the result with half the effort.

The "Dietary Guidelines for Chinese Residents (2022)" mentions that we should adhere to a balanced diet based on grains: eat more fruits and vegetables, milk, whole grains, and soy; eat fish, poultry, eggs, and lean meat in moderation; eat less oil and salt, control sugar and limit alcohol; eat regularly and drink enough water; consume an average of more than 12 kinds of food per day, and 25 kinds per week. People of all ages should engage in physical activity every day, walk 6,000 steps a day, and engage in moderate-intensity physical activity at least 5 days a week, accumulating more than 150 minutes, and encourage the public to engage in high-intensity aerobic exercise and strengthen resistance exercise 2-3 days a week.

Overweight and obesity are not just a personal weight crisis, but one of the most serious public health problems in the world. The trend of obesity is coming to us. We are born in a new era. While enjoying unprecedented material abundance, we also have to face this "sweet burden". We should establish a vigilance against obesity, start from ourselves, improve the eating environment, strengthen physical exercise, and welcome a better future!

References:

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[2]Wang W, Seale P. Control of brown and beige fat development[J]. Nature Reviews Molecular Cell Biology, 2016, 17(11): 691-702.

[3]Cheong LY, Wang B, Wang Q, et al. Fibroblastic reticular cells in lymph node potentiate white adipose tissue beiging through neuro-immune crosstalk in male mice[J]. Nature Communications, 2023, 14(1): 1213.

[4]Bonet ML, Oliver P, Palou A. Pharmacological and nutritional agents promoting browning of white adipose tissue[J]. Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids, 2013, 1831(5): 969-985.

[5]Cohen P, Kajimura S. The cellular and functional complexity of thermogenic fat[J]. Nature Reviews Molecular Cell Biology, 2021, 22(6): 393-409.

[6]Peirce V, Carobbio S, Vidal-Puig A. The different shades of fat[J]. Nature, 2014, 510(7503): 76-83.

Image source:

[1]Bartelt A, Heeren J. Adipose tissue browning and metabolic health[J]. Nature Reviews Endocrinology, 2014, 10(1): 24-36.

[2]Cohen P, Kajimura S. The cellular and functional complexity of thermogenic fat[J]. Nature Reviews Molecular Cell Biology, 2021, 22(6): 393-409.

This article is a work of Science Popularization China-Starry Sky Project

Produced by: Science Popularization Department of China Association for Science and Technology

Producer｜China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Peng Minmin, Liang Yiying, Lu Chan, Ni Linjie, Chen Ronghe, popular science creators

Review | Wang Hongwei, Standing Committee Member of the Probiotics and Prebiotics and Health Branch of the Chinese Nutrition Society