As we all know, obesity can cause many diseases. But in recent years, a strange phenomenon has appeared in many studies: obese patients have lower mortality than normal weight.
Is it possible to eat and drink without any burden, and live simple and happy? Does such a good thing really exist?
It’s pretty to think about it, what about these studies?
What, the study found that obese people live longer?
Things go back to 1999, when Darren S. Schmidt, a researcher at the University of Mississippi Medical Center, and his colleagues accidentally discovered that patients with kidney failure were overweight and obese compared with normal weight. After hemodialysis, the life span is longer. They described this phenomenon as "obesity - survival paradox."
Coincidentally, in the past two decades, obesity paradox has also appeared in related studies of cardiovascular diseases, lung diseases, cancer and other diseases. For example, a study published in the Lancet in 2006 showed that among cardiovascular diseases, overweight people were 18% less likely to die than normal weight.
This discovery subverts the three views of the researchers. Who can think of the healthy enemy who has struggled for decades and finally turned out to be a healthy protector? This kind of taste must be a difficult word.
Is it really fat people who have fat blessings? The answer is of course no.
When it comes to obesity, you have to mention the Body Mass Index (BMI). BMI is a commonly used standard for measuring the degree of obesity in the world, and it is also the most commonly used index for studying the relationship between obesity and disease and death. It is calculated by dividing the weight (kg) by the square of the height (m).
According to Chinese standards, BMI is normal weight from 18.5 to 23.9.
There must be a problem here.
Over the past decade or so, researchers have waged long guerrilla warfare with obesity paradox, striving to find out the flaws of obesity paradox, and also proposed various possible reasons.
For example, some researchers have found that there are often age differences between obese and normal-weight patients. Because obesity can cause many health problems, fat people usually have an earlier onset, which makes obese patients usually younger and therefore have a higher survival rate and live longer. But in other studies, obesity paradox still exists even if the age variable is controlled. It can be seen that the age difference may be one of the reasons for the public opinion, but it is not the whole truth.
In addition, in cardiovascular disease research, indicators of obesity sometimes affect outcomes. When using BMI to measure the degree of obesity, it does not reflect the distribution of fat in the body. Among cardiovascular diseases, the most harmful type of obesity is centripetal obesity, which is the fatness of the big belly and thin limbs. If the proportion of central obesity in the high BMI population is low, then there is a possibility of obesity paradox. However, this reason cannot explain the obesity paradox that appears in other disease studies.
In cardiovascular disease, the most harmful type of obesity is centripetal obesity.
Some scholars have pointed out that obesity may not be the cause of longevity, but the fruit of longevity. This causal inversion will also have an impact on the outcome. A relatively thin patient may have suffered from multiple diseases at the same time, from a fat one to a thin one, and his life is impaired due to illness. Therefore, it is not the fat man who has lived for a long time, but the person who has not been dragged into a thin child by the disease has longevity. But this statement still lacks evidence to support.
A large cohort study in 2018 pointed out that among cardiovascular diseases, the lowest risk of death is in normal-weight populations. The study was followed for more than 25 years and was longer than previous studies. Therefore, insufficient follow-up may also cause obesity paradox. In the absence of follow-up, it may not be possible to distinguish between normal-weight populations and the risk of death in overweight and obese people.
Fat man has no fat fortune
Of course, not all studies will have obesity paradox, and in the study of obesity paradox, its meaning must not be as fat as you like. Excess fat is a heavy burden on the body.
Obesity increases the risk of many diseases, such as high blood pressure, heart disease, hepatobiliary diseases, gout, cancer, etc., and affects fertility. Previous large studies have also shown that as the BMI rises, population mortality increases. There is even evidence that a steady increase in human life expectancy over the past two centuries may end with an increase in the prevalence of obesity.
Some interesting numbers:
The mortality rate of severely obese people (BMI ≥ 40) is twice that of normal BMI.
More than 80% of diabetes is caused by obesity.
Overweight people are susceptible to 13 types of cancer. Among them, in obese men, for every 5 increase in BMI, the risk of esophageal cancer increased by 52%. In obese women, for every 5 increase in BMI, the risk of endometrial cancer is increased by 59%, gallbladder cancer is increased by 59%, and esophageal cancer is 51%.
One-third of obese men with sexual dysfunction can improve their symptoms through weight loss.
If there is no obesity, the proportion of knee osteoarthritis in the population will drop by 50% in the United States and by 8% in China.
In short, the cause of obesity paradox is complicated, and it still needs a more comprehensive and persuasive reason to interpret. What we can know now is that it must not be because obesity makes people healthy.
Therefore, we have to face the reality - still maintain normal weight, that is really healthy.