You Plow Is The Obesity Paradox An Illusion?
Over the lastly ii decades, multiple independent inquiry groups have got come upwards to the surprising determination that people alongside obesity (or, to a greater extent than commonly, overweight) mightiness genuinely live healthier than thin people inwards sure ways. This finding is called the "obesity paradox". Yet recent inquiry using to a greater extent than rigorous methods is suggesting that the paradox is an illusion-- too excess trunk fatty may live fifty-fifty to a greater extent than harmful to wellness than nosotros thought.
Introduction. What is the obesity paradox, too why does it matter?
We have got an enormous scientific literature suggesting that excess trunk fatty increases the gamble of many diseases, including the ones that kill us most-- cardiovascular disease, cancer, too diabetes. Yet unopen to the plough of the 21st century, prove began to emerge that the floor mightiness non live hence simple.
Researchers reported that people alongside cardiovascular disease, kidney disease, too lung affliction tended to fare amend when they had obesity than when they didn't (1). Then inwards 2005, a National Institutes of Health researcher named Katherine Flegal dropped a bombshell on the inquiry community: inwards her analysis of Centers for Disease Control data, people who were overweight had a lower overall mortality gamble than people who were thin or obese (2). In other words, people who acquit some excess fatty are the to the lowest degree probable to die, implying that they're the healthiest overall.
Flegal followed this upwards alongside to a greater extent than papers inwards a similar vein, including a 2013 meta-analysis representing 2.88 i chiliad 1000 people that confirmed her group's previous finding: overweight people, non thin people, have got the lowest mortality gamble (3).
The potential implications of these findings are enormous. Two-thirds of American adults have got obesity or overweight, too nosotros know that major weight loss is hard to accomplish too sustain. If the obesity paradox is true, hence it implies that nosotros should simply halt pestering people to lose weight-- there's no occupation to laid out with! This is a comforting sentiment for people who acquit excess weight, especially if they've struggled alongside weight loss.
It's besides a comforting sentiment for the carbohydrate H2O industry, including companies similar Coca-Cola. If obesity isn't every bit bad every bit nosotros thought, hence maybe carbohydrate H2O isn't every bit bad every bit nosotros sentiment either. Coca-Cola has funded several researchers whose run supports the obesity paradox* (4). I'm non questioning the integrity of these researchers, but Coca-Cola's involvement inwards this sentiment for sure highlights its importance.
But is it real?
The sentiment of an obesity paradox was controversial from the beginning, too many people have got critiqued it over the years. This came to a caput inwards 2013, when Walter Willett, chair of the Harvard Department of Nutrition, aggressively criticized Flegal's study, stating on NPR that it "is genuinely a pile of rubbish, too no i should waste materials their fourth dimension reading it". He besides organized a symposium at Harvard explicitly to criticize the concept (5). Willett was rebuked for his aggressive tactics, but despite this, many people agreed alongside his scientific position.
The primal occupation alongside the obesity paradox is that it's based almost exclusively on observational evidence, pregnant that it doesn't come upwards from controlled experiments that are amend at identifying cause-effect relationships. And inwards this special case, it's non hard to imagine ways inwards which observational methods could obscure the truthful human relationship betwixt trunk fatness too health. In other words, the obesity paradox could live nada to a greater extent than than an illusion of the special inquiry methods that were used to seat it**.
How mightiness this work? As an example, nosotros know that illnesses such every bit diabetes too Alzheimer's affliction oft Pb to weight loss (sometimes many years earlier diagnosis, pregnant that yous can't exclusively eliminate the occupation past times excluding people alongside diagnosed disease). So if you're currently thin too sick, researchers may associate your illness alongside the thin category, fifty-fifty if yous used to live overweight, too fifty-fifty if that excess fatty caused your illness to laid out with.
Influenza A virus subtype H5N1 similar phenomenon happens alongside cigarette smoking. Smoking causes weight loss, too it's besides a fast rails to illness too premature death. It's non hard to imagine how smokers mightiness brand leanness await a lot to a greater extent than unsafe than it genuinely is. It's besides non hard to imagine that some smokers don't accurately written report their smoking habits, making it hard to fully occupation concern human relationship for inwards studies.
Researchers have got recognized these pitfalls for many years, too those who did the best undertaking of correcting for them ordinarily flora that thin people tend to live healthiest (6, 7). Yet a novel inquiry method developed past times Andrew Stokes, assistant professor of global wellness at Boston University, promises to render the clearest motion-picture demonstrate nevertheless of the truthful human relationship betwixt trunk weight too health.
To minimize the pitfalls of traditional methods, Stokes looks non only at electrical current trunk weight, but at weight history. He asks a unproblematic question: how does a person's maximum attained weight associate alongside wellness outcomes? Weight is compared using the trunk majority index (BMI) scale, which corrects for the effects of peak on weight.
Maximum weight should produce a amend undertaking of capturing the trial of excess trunk fatty on health, because traditional methods don't consider the possibility that a somebody mightiness have got previously carried to a greater extent than fat, too may have got been exposed to its damaging (or protective) effects for many years. If this is true-- which seems fairly obvious to me-- hence Stokes's method is a amend examine of the obesity paradox hypothesis than previous methods.
In 2014, I wrote almost Stokes's foremost study using this method, which suggests that thin people have got lower mortality gamble than people who are overweight or obese (8). Recently, Stokes too his mentor Samuel Preston published ii to a greater extent than papers on the subject, too they are much to a greater extent than detailed (9).
Using the maximum weight method, Stokes confirmed his previous finding that people who stay thin throughout life have got the lowest gamble of dying. Consistent alongside this, they besides have got the lowest gamble of developing diabetes too cardiovascular disease. Both associations were substantial. Furthermore, people who already have got diagnosed cardiovascular affliction have got a higher gamble of dying if they're besides obese, non lower. There is no paradox inwards these data, which is a expert sign that nosotros finally empathize what's going on. It's besides reassuring that his results align good alongside what nosotros know from experimental studies inwards animals too humans.
His newspaper goes on to render valuable insight into why previous studies oft went astray. With the weight history method, he was able to demonstrate that people who lost weight too went downwards a BMI category were inflating the gamble degree of that category, confirming that this was warping the results of previous studies. The most probable explanation is that these people were losing weight due to illness (perhaps subclinical) or smoking (perhaps unreported), making leanness appear less salubrious than it is.
As a reminder, at that topographic point is no prove that voluntary fatty loss is unhealthy, too quite a fleck of prove that it's beneficial (10).
Conclusion
The obesity paradox is likely an illusion of the inquiry methods that are used to investigate the human relationship betwixt trunk weight too health. We tin never live sure that the results of observational studies are gratis of confounding, but at that topographic point are expert reasons to believe that Stokes's maximum attained weight method is to a greater extent than accurate than methods that only consider a weight snapshot. I hope these findings volition induce other researchers to adopt his methods.
* To my knowledge, Flegal has never received funding from Coca-Cola. But inwards whatsoever case, I don't recollect it's ethical to assume a researcher is biased past times a funding source without prove to back upwards that accusation. It's logical to recollect inwards a full general feel that manufacture funding has the potential to bias research, but specific accusations need specific evidence. I don't abide by it especially rational to dismiss inquiry findings out of manus simply because of a funding source. In fact, ironically, this is i of the most mutual fence tactics used past times people who are ideologically biased themselves.
** We tin add together this to a long listing of wrong conclusions that have got resulted from confounding inwards observational studies. A few examples off the transcend of my head: the human relationship betwixt calorie intake too trunk weight, the trial of vitamin E on cardiovascular health, too the trial of hormone replacement therapy on cardiovascular health.
Introduction. What is the obesity paradox, too why does it matter?
We have got an enormous scientific literature suggesting that excess trunk fatty increases the gamble of many diseases, including the ones that kill us most-- cardiovascular disease, cancer, too diabetes. Yet unopen to the plough of the 21st century, prove began to emerge that the floor mightiness non live hence simple.
Baca Juga
Researchers reported that people alongside cardiovascular disease, kidney disease, too lung affliction tended to fare amend when they had obesity than when they didn't (1). Then inwards 2005, a National Institutes of Health researcher named Katherine Flegal dropped a bombshell on the inquiry community: inwards her analysis of Centers for Disease Control data, people who were overweight had a lower overall mortality gamble than people who were thin or obese (2). In other words, people who acquit some excess fatty are the to the lowest degree probable to die, implying that they're the healthiest overall.
Flegal followed this upwards alongside to a greater extent than papers inwards a similar vein, including a 2013 meta-analysis representing 2.88 i chiliad 1000 people that confirmed her group's previous finding: overweight people, non thin people, have got the lowest mortality gamble (3).
The potential implications of these findings are enormous. Two-thirds of American adults have got obesity or overweight, too nosotros know that major weight loss is hard to accomplish too sustain. If the obesity paradox is true, hence it implies that nosotros should simply halt pestering people to lose weight-- there's no occupation to laid out with! This is a comforting sentiment for people who acquit excess weight, especially if they've struggled alongside weight loss.
It's besides a comforting sentiment for the carbohydrate H2O industry, including companies similar Coca-Cola. If obesity isn't every bit bad every bit nosotros thought, hence maybe carbohydrate H2O isn't every bit bad every bit nosotros sentiment either. Coca-Cola has funded several researchers whose run supports the obesity paradox* (4). I'm non questioning the integrity of these researchers, but Coca-Cola's involvement inwards this sentiment for sure highlights its importance.
But is it real?
The sentiment of an obesity paradox was controversial from the beginning, too many people have got critiqued it over the years. This came to a caput inwards 2013, when Walter Willett, chair of the Harvard Department of Nutrition, aggressively criticized Flegal's study, stating on NPR that it "is genuinely a pile of rubbish, too no i should waste materials their fourth dimension reading it". He besides organized a symposium at Harvard explicitly to criticize the concept (5). Willett was rebuked for his aggressive tactics, but despite this, many people agreed alongside his scientific position.
The primal occupation alongside the obesity paradox is that it's based almost exclusively on observational evidence, pregnant that it doesn't come upwards from controlled experiments that are amend at identifying cause-effect relationships. And inwards this special case, it's non hard to imagine ways inwards which observational methods could obscure the truthful human relationship betwixt trunk fatness too health. In other words, the obesity paradox could live nada to a greater extent than than an illusion of the special inquiry methods that were used to seat it**.
How mightiness this work? As an example, nosotros know that illnesses such every bit diabetes too Alzheimer's affliction oft Pb to weight loss (sometimes many years earlier diagnosis, pregnant that yous can't exclusively eliminate the occupation past times excluding people alongside diagnosed disease). So if you're currently thin too sick, researchers may associate your illness alongside the thin category, fifty-fifty if yous used to live overweight, too fifty-fifty if that excess fatty caused your illness to laid out with.
Influenza A virus subtype H5N1 similar phenomenon happens alongside cigarette smoking. Smoking causes weight loss, too it's besides a fast rails to illness too premature death. It's non hard to imagine how smokers mightiness brand leanness await a lot to a greater extent than unsafe than it genuinely is. It's besides non hard to imagine that some smokers don't accurately written report their smoking habits, making it hard to fully occupation concern human relationship for inwards studies.
Researchers have got recognized these pitfalls for many years, too those who did the best undertaking of correcting for them ordinarily flora that thin people tend to live healthiest (6, 7). Yet a novel inquiry method developed past times Andrew Stokes, assistant professor of global wellness at Boston University, promises to render the clearest motion-picture demonstrate nevertheless of the truthful human relationship betwixt trunk weight too health.
To minimize the pitfalls of traditional methods, Stokes looks non only at electrical current trunk weight, but at weight history. He asks a unproblematic question: how does a person's maximum attained weight associate alongside wellness outcomes? Weight is compared using the trunk majority index (BMI) scale, which corrects for the effects of peak on weight.
Maximum weight should produce a amend undertaking of capturing the trial of excess trunk fatty on health, because traditional methods don't consider the possibility that a somebody mightiness have got previously carried to a greater extent than fat, too may have got been exposed to its damaging (or protective) effects for many years. If this is true-- which seems fairly obvious to me-- hence Stokes's method is a amend examine of the obesity paradox hypothesis than previous methods.
In 2014, I wrote almost Stokes's foremost study using this method, which suggests that thin people have got lower mortality gamble than people who are overweight or obese (8). Recently, Stokes too his mentor Samuel Preston published ii to a greater extent than papers on the subject, too they are much to a greater extent than detailed (9).
Using the maximum weight method, Stokes confirmed his previous finding that people who stay thin throughout life have got the lowest gamble of dying. Consistent alongside this, they besides have got the lowest gamble of developing diabetes too cardiovascular disease. Both associations were substantial. Furthermore, people who already have got diagnosed cardiovascular affliction have got a higher gamble of dying if they're besides obese, non lower. There is no paradox inwards these data, which is a expert sign that nosotros finally empathize what's going on. It's besides reassuring that his results align good alongside what nosotros know from experimental studies inwards animals too humans.
His newspaper goes on to render valuable insight into why previous studies oft went astray. With the weight history method, he was able to demonstrate that people who lost weight too went downwards a BMI category were inflating the gamble degree of that category, confirming that this was warping the results of previous studies. The most probable explanation is that these people were losing weight due to illness (perhaps subclinical) or smoking (perhaps unreported), making leanness appear less salubrious than it is.
As a reminder, at that topographic point is no prove that voluntary fatty loss is unhealthy, too quite a fleck of prove that it's beneficial (10).
Conclusion
The obesity paradox is likely an illusion of the inquiry methods that are used to investigate the human relationship betwixt trunk weight too health. We tin never live sure that the results of observational studies are gratis of confounding, but at that topographic point are expert reasons to believe that Stokes's maximum attained weight method is to a greater extent than accurate than methods that only consider a weight snapshot. I hope these findings volition induce other researchers to adopt his methods.
* To my knowledge, Flegal has never received funding from Coca-Cola. But inwards whatsoever case, I don't recollect it's ethical to assume a researcher is biased past times a funding source without prove to back upwards that accusation. It's logical to recollect inwards a full general feel that manufacture funding has the potential to bias research, but specific accusations need specific evidence. I don't abide by it especially rational to dismiss inquiry findings out of manus simply because of a funding source. In fact, ironically, this is i of the most mutual fence tactics used past times people who are ideologically biased themselves.
** We tin add together this to a long listing of wrong conclusions that have got resulted from confounding inwards observational studies. A few examples off the transcend of my head: the human relationship betwixt calorie intake too trunk weight, the trial of vitamin E on cardiovascular health, too the trial of hormone replacement therapy on cardiovascular health.
