How do we explain the studies that suggest that overweight people live more?
Martin Luther King Jr. warned that human progress is not automatic or inevitable, and the same can be true with human life. In the nineteenth century, life expectancy was less than 40 years, but it has been «advanced With constantly «in the last two centuries,» increasing approximately 2 years per decade «, until recently. Longevity profits seem to» hesitate or even revert. «Thanks to the obesity epidemic, we can now be raising the first generation for live shorts shorter than their parents.
“This descending trend in longevity is almost certain accelerate Like the current generation of children, with greater body weights before in life than ever, it reaches adulthood. «The current trends» potentially indicate an imminent social and economic catastrophe «if the obesity epidemic continues without control. In the next decades, some predict We can lose two or five years or more of life expectancy in the United States. To put that in perspective, a miraculous cure for all forms of cancer would only add three and a half years to the average life expectancy of the United States. In other words, reverse the epidemic of obesity could save more lives than cure cancer.
The evidence that having overweight increase Our risk of weakening diseases such as diabetes is considered «indisputable.» However, surprisingly, there is a controversy around body weight and general mortality. In 2013, scientists with the centers for disease control and prevention (CDC) published a meta -analysis in the Journal of the American Medical Association suggesting that having overweight was advantageous. Grades 2 and 3 obesity, such as having an average height of 5’6 ″ and a weight of around 216 pounds (98 kg) or more, were associated with living a shorter life, but the obesity of grade 1, which weighed Around 185 to 215 pounds (84 to 97 kg) at that point, it was not. Be overweight (around 155 to 185 pounds/70 to 83 kg to 5’6 ″) seemed to be protective compared to those who had a «normal weight» from 115 to 155 pounds (52 to 69 kg). Overweight individuals, those with a body mass index (BMI) from 25 to 30, seemed to live longer.
The headlines were dizzy. «Be overweight can Extend your life instead of shortening it, ”read one. «Fear Your diet? Do not worry: people cry longer than their thinner counterparts … «Read another.» Extra pounds mean a lower possibility of death. «It is not surprising that the study lit a controversy storm in the public health community. The study was called» ridicule «,» defective «and» misleading. «The nutrition chair in Harvard lost its calm , vocation The study «really a lot of garbage» and fearing that the food industry can exploit the study in the same way that the oil industry uses poor «controversy» on climate change.
However, public health defenders cannot simply rule out data that find inconveniences. Science is science. But how could it be overweight to increase the risk of potentially fatal diseases, however, at the same time, make you live longer? This became acquaintance As «the paradox of obesity», the theme of my video Is the paradox of obesity real or a myth?.
The solution to the puzzle seems lie With two main sources of bias, the first is «confused by smoking.» Nicotine in tobacco can lead to weight loss. So, if you are thinner because you smoke, then it is not surprising that you would live a shorter life, although with a thinner waist. The disability control The effect of smoking on studies that aims to show a «paradox of obesity» leads to the dangers that obesity «underestimated.»
The second main source of bias is reverse causality. Instead of a lower weight that leads to potentially mortal diseases, isn’t it more likely that diseases that threaten life lead to less weight? Conditions such as hidden tumors, chronic cardiac or pulmonary disease, alcoholism and depression can all cause Involuntary weight loss for months or even years before they are diagnosed. It is normal to be Overweight in the United States, for example. So, people who are «Abnormally» thin, in other words, with an ideal weight, you can take care of themselves, but instead they can be «heavy smokers, fragile and elderly, and seriously ill with weight loss due to their disease …»
To test the obesity paradox once and for all, the global BMI mortality collaboration was formedReviewing data from more than 10 million people from hundreds of studies in dozens of countries, the largest evaluation of BMI and mortality in history. To help eliminate bias, the researchers omitted the smokers and those with known chronic diseases, then excluded the first five years of follow -up to try to eliminate the analysis of those with non -diagnosed conditions that lost weight due to imminent death. AND? The results were Of course: «This analysis has shown that both overweight and obesity (all grades) were associated with greater mortality from all causes», an greater risk of dying prematurely. So, “adjusting for these biases leads to eliminating The paradox of obesity. «In other words, the so -called paradox of obesity appear Be «just a myth.»
In fact, when intentional weight loss is tested, people live more. There are bariatric surgery studies such as essay SOSs that show that weight loss reduces long -term mortality, and randomization Study participants for weight loss through changes in lifestyle show the same. It was discovered that losing a dozen pounds through the diet and exercise were associated with a 15 percent drop in general mortality. Now, exercise can only extend useful life even without losing weight, but it seems be A similar longevity benefit of weight loss through dietary means alone.
If you missed the previous blog posts of my series about the ABCS of obesity, look:
Look at the last two videos of this series: What is the ideal BMI? and What is the ideal waist size?.
I cover all this and more extensively in my book How not to dietAnd his partner, The kitchen book as not dietIt has more than 100 delicious green light recipes that incorporate some of my 21 adjustments for the acceleration of body fat loss.
Why are people obese first? I have a complete series of videos on that topic. See videos in related publications.
