A eating habit that can prolong your life is really simple to do! I strongly recommend you try it

Recently, Zhang Yun, an academician of the Chinese Academy of Engineering, mentioned in an interview that being 80% full and feeling hungry will activate longevity genes; not wearing warm clothes and feeling a little cold will also activate longevity genes. On the surface, these two sentences seem to be counterintuitive - we often use "hunger and cold" to describe a person in adversity, and hunger and cold, which everyone is afraid to avoid, can actually promote longevity?

In fact, despite some simplifications, the information conveyed by these two sentences has long been supported by research results, and the biological principles behind them have also been explored to a certain extent.

The Science of Hunger

Speaking of hunger, you may have heard of the concept of "intermittent fasting" in recent years. The definition of "hunger" in biological research is more precise and complex. A review published in Nature Aging in 2021 concluded that intermittent fasting belongs to the category of "intermittent diet" in science, which can be roughly divided into several types:

Alternate-day fasting (ADF) means eating normally one day and consuming only water on the other day; the 5:2 diet means eating normally five days a week and consuming only 500 to 700 calories on the remaining two days;

Time-restricted feeding (TRF) divides the day into two periods, restricting eating time to the shorter period (generally 6-12 hours), and not allowing food to be eaten during the remaining time.

Some more extreme methods extend the fasting period to 1-2 days, but this is generally rare.

In general, the key to intermittent eating is the "intervals", a period of normal eating and a period of restricted calorie intake. The "starvation" phase is the key because it can start the metabolic mode switch.

In most mammals, excess glucose is stored in the liver in the form of glycogen. After a period of fasting, as blood sugar levels drop, liver glycogen is gradually consumed to maintain blood sugar. When liver glycogen reserves are insufficient, the body switches its metabolic mode and uses ketone bodies and fat as energy sources, which is what we commonly call "burning fat."

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Fat was originally a weapon used by our ancestors to store energy and resist the severe cold in winter when it was difficult to find food. However, with the continuous improvement of living standards, modern people are less likely to go hungry and more likely to eat too much, and fat continues to accumulate, causing an obesity epidemic. According to the World Health Organization (WHO), in 2022, one in every eight people will be obese. As weight increases, the risk of various diseases will also increase.

Therefore, "burning fat" itself can reduce the risk of modern "diseases of affluence". Some studies have also pointed out that this metabolic pattern can help people better cope with stress and prolong their lifespan.

In addition, fasting can activate the autophagy reaction in the human body through the relevant cell signaling pathways in the human body, causing the damaged aging cells to undergo apoptosis. After resuming eating, the influx of nutrients can promote cell regeneration. In a sense, the cycle of fasting and resuming eating is like giving cells an opportunity to innovate and renew. In this way, the corresponding tissues and organs will become younger and healthier.

The Mystery of Cold

In the martial arts novel The Return of the Condor Heroes, there is a magical cold jade bed. People who sleep on it will feel extremely cold and must use all their strength to fight the cold. Even in their dreams, they are practicing martial arts unconsciously. Over time, the internal strength will naturally be perfected.

Although this is a magical setting in martial arts novels, in recent years, researchers have also become increasingly aware of the benefits of cold weather to animals. For example, if the commonly used model organism nematodes are moved from a living environment of 20 degrees to a higher temperature, their lifespan will be shortened. On the contrary, if they are moved to an environment of about 15 degrees, their lifespan can be significantly extended.

In mice, researchers have seen similar results. Just an environment 0.5 degrees higher than body temperature is enough to shorten their lifespan. Conversely, if the environment is 0.5 degrees lower than body temperature, the lifespan of mice can be extended. These studies clearly show that there is an inextricable connection between temperature and lifespan.

Scientists are trying to find the reason behind this. Also in Nature Aging, a paper published last year found that lower temperatures can activate the proteasome in nematodes to degrade the aggregated pathogenic proteins. When they switched from nematodes to human cells, they observed the same result: at 36 degrees, the proteasome in human cells began to start and destroy the disease-related proteins in the cells. This may explain some of the benefits of cold.

Some other explanations are simpler and more straightforward: in a low-temperature environment, the rates of all biochemical reactions will slow down, which will naturally slow down the pace of aging; in addition, low temperatures can also promote the burning of fat, which can relieve a lot of worries.

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These explanations all sound reasonable, but it should be pointed out that our understanding of cold is still very preliminary, and there are still many mysteries to be solved. For example, a study conducted by the University of Michigan and Huazhong University of Science and Technology found that in adult nematodes, low temperature can activate a protein called TRPA1 located on nerve cells and fat cells, initiate a series of biochemical reactions, and ultimately activate the longevity gene DAF-16/FOXO.

Interestingly, the same environment has the opposite effect on nematode larvae. In fact, larvae living in warmer environments live 20% longer. These seemingly contradictory data also tell us that we still have a lot to explore about the impact of temperature on organisms.

The revelation of “hunger and cold”

Existing scientific research can only explain what reactions can occur in organisms when facing hunger or cold, and how they can potentially affect health, but cannot answer the question "why is this the case". For this reason, people have made many speculations. One explanation is that modern society is developing too fast and the body has not kept up with this speed.

If we imagine the human body as a smartphone, then the genome is our hardware, which determines our performance ceiling; and the various stimuli from the environment are like software, which has undergone rapid upgrades and iterations over the past thousands of years. Today, we can sit in a constant temperature office for a long time, with a variety of food and sugary drinks at our fingertips, and we don’t have to run around like our hunter-gatherer ancestors. We have built a comfortable environment, but it makes the body feel at a loss. Some of the so-called adversities that seem to be at the moment are actually closer to the environment that the human body is familiar with, allowing it to return to a healthier state.

Of course, the above statement can only be regarded as a hypothesis, which needs more evidence to confirm. However, for modern people who want to improve their health, there is no need to sort out the ins and outs behind it. Perhaps as long as you follow some practices supported by human research (such as intermittent fasting, short-term high-intensity exercise, etc., you can review previous articles), you can see the benefits.

In addition, we can also wait for the latest achievements of the scientific community. At this year's spring meeting of the American Chemical Society, researchers at Washington University in St. Louis found a compound that can simulate the effects of exercise on the human body. This undoubtedly provides a new health idea for using drugs to simulate adversity. We also look forward to more similar drugs appearing in the future, so that we can enjoy the same health benefits without experiencing uncomfortable feelings such as hunger and cold.

References

[1]Intermittent and periodic fasting, longevity and disease, https://www.nature.com/articles/s43587-020-00013-3

[2] Effects of Intermittent Fasting on Health, Aging, and Disease, https://www.nejm.org/doi/full/10.1056/NEJMra1905136

[3]Obesityandoverweight, https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight

[4]Coldtemperatureextendslongevityandpreventsdisease-relatedproteinaggregationthroughPA28γ-inducedproteasomes, https://www.nature.com/articles/s43587-023-00383-4

[5]Coldimproveslongevityforsome,shortenslifespanforothers, https://news.umich.edu/cold-improves-longevity-for-some-shortens-life-span-for-others/

[6]Mimickingexercisewithapill, https://www.acs.org/pressroom/presspacs/2024/march/mimicking-exercise-with-a-pill.html

Planning and production

Author: Ye Shi Popular Science Creator

Review丨Zhang Yu, researcher/PhD, Chinese Center for Disease Control and Prevention, national health science expert