Being fat has the benefits of being fat!
Writing | Jiaying Bai
Source | “Medical Community” Public Account
Obesity has always been regarded as a risk factor affecting the health of the body. Today, in this era of “l is beauty” as the mainstream aesthetic, obese people may also face serious social discrimination.
Image source: Ruijing Creative
However, on April 25, Shi Xiaoming’s team from the Chinese Center for Disease Control and Prevention’s Environmental and Health-Related Product Safety Institute published a 20-year prospective cohort study in the sub-journal of Nature. Overweight or mild obesity in the elderly over the age of 80 is associated with lower mortality, supporting the existence of an “obesity paradox” in China’s oldest population (80 years and older).
Screenshot of research publication
The “obesity paradox” was an unexpected finding in 1999 by University of Mississippi Medical Center researchers Schmidt and colleagues when they crunched data: Compared with normal weight, overweight and obese patients with kidney failure The survival advantage of hemodialysis is more obvious.
Deviant “science”?
The “obesity paradox” has been found in patients with cardiovascular disease.
A previous study showed that among people 70 years and older, the relative risk of death from cardiovascular disease is much lower in people who are overweight or obese than in younger people. However, few studies have addressed the potentially complex inverse association between body mass index (BMI) and cause-specific mortality in older adults.
BMI is a standard commonly used internationally to measure the degree of body fat, thinness and health. The calculation formula is: BMI=weight÷height2 (weight unit: kilogram; height unit: meter).
BMI greater than 25 is overweight and greater than 30 is obese. Source: Ruijing Creative
In this study by Shi Xiaoming’s team, the research team reported the relationship between BMI and mortality risk in 27,026 community-based elderly people (average age: 92.7±7.5 years) in China from 1998 to 2018. This study provides evidence suggesting that “normal” body weight (18.5-24.0 kg/m2) in older adults may need to be redefined.
Analysis of BMI and mortality showed that overweight and obesity were not significantly associated with cardiovascular mortality compared with normal weight, but were associated with non-cardiovascular mortality and all-cause mortality associated with a significantly lower mortality rate.
BMI and all-cause, cardiovascular and non-cardiovascular mortality in older adults. Source: Nature Aging
Meanwhile, the study points to additional data showing that traditional cardiovascular risk factors, such as hypercholesterolemia and high blood pressure, are at odds with better survival in older adults. Considering this finding, it is not surprising that in this study, overweight and obesity were not associated with an increased risk of death from cardiovascular disease, but were associated with a reduction in non-cardiovascular mortality.
A more sensitive indicator of waist obesity
The research team further analyzed the association between the risk of death and waist circumference in this group of overweight or obese people. Inverse associations of waist circumference with all-cause and non-cardiovascular mortality were observed in both men and women. Although waist circumference was significantly associated with increased cardiovascular mortality in men, this association was not observed in women.
Association of waist circumference with all-cause, cardiovascular, and noncardiovascular mortality in men and women. Source: Nature Aging
Overweight and obesity may be an indicator of improved nutritional status, and the benefits of better nutrition outweigh the harms of higher BMI, which may partially explain the association between BMI and mortality negative correlation. Compared with BMI, waist circumference provided a more sensitive measure of abdominal obesity and showed increased non-cardiovascular mortality associated with these measures.
In the older adults in this study, waist circumference increased and non-cardiovascular mortality decreased, the researchers speculated that obesity may provide protective energy reserves, protective adipokines , endotoxin-lipoprotein interactions, and/or toxin sequestration of fat, resulting in a survival advantage.
It is worth mentioning that a previous meta-analysis of 19,538 older adults with a median age of 84.2 years, including 20 studies in Europe, Asia, North America and Australia, An inverse association between BMI and mortality was also found. In conclusion, the inverse association between high BMI and mortality in the elderly was broadly similar not only among Chinese elderly but also among Asians, North Americans, and Europeans.
80 years and aboveOlder Chinese, optimal BMI should be raised
Nature Aging published a concurrent review article from Jean Woo of the Chinese University of Hong Kong, which pointed out that public health policy recommends keeping a BMI below 25, otherwise it will be considered overweight or obese. The study published by Shi Xiaoming’s team suggests that the optimal BMI should probably be raised for Chinese seniors aged 80 and older.
Senior adults 80 years and older were followed longitudinally for up to 20 years in this study. The researchers linked BMI to all-cause mortality (and subdivided into cardiovascular and non-cardiovascular disease) and found that the optimal BMI associated with decreased mortality was between 26-30.6.
Optimal BMI for all-cause, cardiovascular and non-cardiovascular mortality in people aged 80 and older
In addition, current BMI thresholds for overweight and obesity are based on epidemiological studies of the average adult of all ages, but this study by Shi Xiaoming’s team found a lower risk of death The association of BMI with overweight and even mild obesity also challenges the definition of the range of BMI in the elderly aged 80 and above in my country.
It is worth mentioning that although the “obesity paradox” breaks the shackles of aesthetics to some extent, it goes against the original conclusion that “obesity affects health”. However, in the past academic circles generally believed that obesity is a risk factor including cardiovascular diseases, diabetes, sleep apnea syndrome, metabolic diseases, endocrine system diseases, cancer, reproductive ability, mental diseases and other diseases.
Therefore, a large proportion of scientists believe that the existence of this theory does not underestimate the possible harm caused by “obesity”.
References:
[1]Lv,Y.,Mao,C.,Gao,X.et al.The obesity paradox is mostly driven by decreased noncardiovascular disease mortality in the oldest old in China:a 20 -year prospective cohort study. Nat Aging(2022).
[2]Whitlock, G. et al. Body-mass index and cause-specific mortality in 900 000
adults:collaborative analyses of 57 prospective studies.Lancet 373,
1083C1096(2009).
https:https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(09)60318-4/fulltext
[3]Lee,D.H.et al.Predicted lean body mass,fat mass,and all cause and cause
specifc mortality in men:prospective US cohort study.BMJ 362,k2575
(2018).
https:https://www.bmj.com/content/362/bmj.k2575
Source: Medicine
Editor in charge: Jun Ling
Proofreading: Zang Hengjia