Is there any scientific basis for the saying “If you want to live longer, eat until you are 70% full”?

Produced by: Science Popularization China Produced by: Ruan Guangfeng, Director of Science and Technology Communication Department of Kexin Food and Health Information Exchange Center Produced by: Computer Network Information Center of Chinese Academy of Sciences

There is a saying among the people that "eat until you are 70% full, and you will live a healthy life". Many people think that "70% full" is a kind of wisdom. On the Internet, it is said that people eat several tons of food in their lifetime, and whoever finishes first will die first, so they should not eat too much, but eat less.

(Photo source: provided by the author)

Recently, a piece of news has been circulating online, saying that the latest research from the University of the Chinese Academy of Sciences found that eating 70% full can resist aging and prolong life. This has made many people believe in "70% full" even more firmly.

However, can eating until you are 70% full really help people live longer? Should we eat until we are 70% full? Today, let’s talk about “eating until you are 70% full”.

Is there any scientific basis for “eating until 70% full”?

(Photo source: provided by the author)

The research mentioned in this article is real and was recently published in Cell by the Chinese Academy of Sciences. What is this research about? Can it really prove that eating 70% full can prevent aging?

(Photo source: provided by the author)

In this study, researchers randomly divided 18-month-old rats that ate the same food and drank the same water into two groups. The first group was the control group, in which the rats could eat as much as they wanted; the second group was the experimental group, in which the food they received was gradually reduced, and finally stabilized at about 70% of the normal food intake, which is commonly known as "70% full".

After 9 months, the rats in the control group and the experimental group basically lived to old age, which is equivalent to about "70 years old" in human age. Next, the scientists compared these "70-year-old" rats with a group of "fresh meat" rats of 5 months old (equivalent to 16 years old in human age) in various details. The results showed that the rats on a diet were not only visibly slimmer, but also showed that they looked younger than rats of the same age. However, this study is only a cell and animal experiment, and the experimental subjects are rats and their organ cells, which are very different from humans, and are not enough to prove that people can live longer if they eat 70% full every day.

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Can eating less help you live longer?

It is said on the Internet that "a person eats about 9 tons of food in his lifetime, and whoever finishes first dies first." So some people say, "Don't eat too much, because eating 70% full can make people live longer." Some people even go further and claim that "dieting can prolong life."

(Photo source: provided by the author) How much food should a person eat in his lifetime? According to the recommendations of my country's dietary pyramid, an average adult should eat 1226 grams to 1821 grams of food every day. Based on the average life expectancy of 77.3 years in my country, this means that an average adult should eat about 34.59 tons to 51.38 tons of food.

(Photo source: Chinese Nutrition Society)

Therefore, the saying that "a person only eats 9 tons of food in his lifetime" is obviously a fabrication without any basis. If a person really only eats 9 tons of food in his lifetime, he would have starved to death long ago.

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So, can dieting and eating less really help people live longer? In fact, "eating until 70% full" is just an empirical statement. In scientific research, it is usually simulated according to the control of energy intake (calorie restriction, CR), which means reducing the energy intake from food while ensuring that other nutrients are sufficient. At present, many studies have indeed found that controlling energy intake is related to extending lifespan. For example, scientists have found that calorie intake does affect the lifespan and quality of life of experimental organisms. In nematodes, yeast, fruit flies, some mice and rats, people have found that restricting calorie intake can extend lifespan. But animals are very different from humans, and the results in different animals are also different. For example, a study on dieting of 41 species of mice found that calorie restriction extended the lifespan of a small number of strains of mice, but shortened the lifespan of more other strains of mice. Inconsistent results were also found in studies on primates that are closer to humans. The National Institute on Aging (NIA) of the National Institutes of Health supports a clinical trial called CALERIE. This experiment has currently produced some experimental results. For example, some studies have found that limiting energy intake can reduce the formation and production of C-reactive protein, cholesterol, creatinine, etc., and can also lower blood lipids and blood pressure, and promote changes in waist circumference and weight in a healthy direction.

However, in these clinical trials, most of the subjects were overweight elderly people. Although some changes in health indicators can be seen in the experiments, such as lower blood lipids and weight loss, these health indicators cannot prove whether they will prolong human life. In addition, the longest period of these experiments was only two years, which is insignificant compared to the entire human life span. Therefore, from the current point of view, the impact of long-term strict calorie control on humans is still unknown. For this reason, the National Institute on Aging (NIA) of the National Institutes of Health believes that it is not yet known whether long-term calorie restriction is beneficial, safe or practical for humans.

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Are there risks in dieting?

For overweight people, eating less can reduce the body's intake of excessive calories and fat, which is indeed good for the stability of blood sugar, blood lipids and weight. However, excessive dieting for ordinary people will harm their health, easily leading to lower blood pressure and blood sugar, slower metabolism, malnutrition and other problems, which is not conducive to extending life. The Chinese Dietary Guidelines also believe that eating too little or too much activity may cause low weight or thinness due to insufficient energy intake or excessive energy consumption. Being overweight or underweight is not a healthy performance, and it is easy to suffer from various diseases and shorten life. The "Minnesota Starvation Experiment" conducted between 1944 and 1945 is a typical case. This experiment recruited 36 healthy male volunteers, and the researchers only provided the subjects with food equivalent to about half of the recommended calorie intake every day for 6 months. The results showed that during the experiment, the subjects experienced symptoms such as slowed metabolism, decreased body temperature and heart rate, edema, and many subjects also experienced loss of libido, depression and severe emotional disorders.

How full is “70%”?

It is okay to advocate not to eat too much or too full. However, I also suggest that you do not blindly pursue the idea of ​​eating until you are 70% full. First of all, it is difficult to judge and operate "70% full". "70% full" is a saying derived from life experience, a description of the feeling of being full, reminding people not to eat too much. But it is not actually an accurate scientific concept. "70% full" is a feeling that varies from person to person and is difficult to measure accurately. Even different nutrition experts have different descriptions of it. For ordinary people, it is even more difficult to operate.

From the three nutrition experts' statements on eating until 70% full, it can be seen that there is no consensus in the nutrition community on this issue.

(Photo source: Interview screenshot)

Secondly, "70% full" is not suitable for everyone. "70% full" is mainly suitable for people who are overweight, have little physical activity, or want to control their weight. But for weak patients, too thin people, and minors who are still in the growth and development period... it is best not to blindly reduce the amount of food, so as not to affect health. Compared with eating "70% full", I suggest that everyone should pay attention to what and how much to eat every day, which is more scientific and reasonable.

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How to eat a balanced diet?

For most people, if they want to live a healthy and long life, they can just arrange their three meals a day according to the "Balanced Diet Pagoda for Chinese Residents" and eat in moderation. How to avoid overeating? It is recommended to start from the following aspects:

(1) Eat at regular times and in regular amounts. Do not wait until you are too hungry to eat, as this will cause you to gulp down and eat too much. It is best to chew your food slowly to avoid accidentally overeating when eating too fast.

(2) Separate dining system. Whether dining at home or out, it is recommended that meals be standardized and quantitatively distributed according to individual physiological conditions and physical activity levels.

(3) Eat one or two bites less at each meal. The key to controlling your diet is to be persistent and steady. For people who are prone to obesity, it is appropriate to limit the amount of food you eat. Do not eat until you are completely full, and do not eat too much. It is best to put down your chopsticks when you feel that you are still a few bites short. Ordinary people should follow the food pyramid to eat safely and exercise moderately. There is no need to deliberately pursue "70% fullness".

(4) Eat less high-energy foods. Learn to read the nutrition facts table, understand the energy content of food, and eat less high-fat, high-sugar and other high-energy foods, such as fried chicken, potato chips, and biscuits.

(5) Reduce the frequency of eating out. When dining out or at a gathering, people usually order a lot and eat a lot, and they eat for a long time. They often reward themselves with a lot of fish and meat, which leads to overeating.

References

[1] http://www.cas.cn/cm/202003/t20200302_4736142.shtml

[2] Ma S, Sun S, Geng L, et al. Caloric Restriction Reprograms the Single-Cell Transcriptional Landscape of Rattus Norvegicus Aging. Cell. 2020 Mar 5;180(5):984-1001.e22. doi: 10.1016/j.cell.2020.02.008. Epub 2020 Feb 27. PMID: 32109414.

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[6] Adam J. Schindler, L. Ryan Baugh, David R. Sherwood. Identification of Late Larval Stage Developmental Checkpoints in Caenorhabditis elegans Regulated by Insulin/IGF and Steroid Hormone Signaling Pathways. PLoS Genetics, 2014; 10 (6): e1004426 DOI: 10.1371/journal.pgen.1004426

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[9] Colman, R., Beasley, T., Kemnitz, J. et al. Caloric restriction reduces age-related and all-cause mortality in rhesus monkeys. Nat Commun 5, 3557 (2014). https://doi.org/10.1038/ncomms4557

[10] Flanagan EW, Most J, Mey JT, Redman LM. Calorie Restriction and Aging in Humans. Annu Rev Nutr. 2020 Sep 23;40:105-133. doi: 10.1146/annurev-nutr-122319-034601. Epub 2020 Jun 19. PMID: 32559388.

[11] Belsky DW, Huffman KM, Pieper CF, Shalev I, Kraus WE. Change in the Rate of Biological Aging in Response to Caloric Restriction: CALERIE Biobank Analysis. J Gerontol A Biol Sci Med Sci. 2017 May 22. doi: 10.1093/gerona/glx096.

[12] Wei, M., Brandhorst, S., Shelehchi, M., Mirzaei, H., Cheng, CW, Budniak, J., ... & Cohen, P. (2017). Fasting-mimicking diet and markers/risk factors for aging, diabetes, cancer, and cardiovascular disease. Science translational medicine, 9(377), eaai8700.

[13] National Institute on Aging(NIA). Calorie Restriction and Fasting Diets: What Do We Know?

https://www.nia.nih.gov/health/calorie-restriction-and-fasting-diets-what-do-we-know

[14] http://en.wikipedia.org/wiki/Minnesota_Starvation_Experiment