Obesity Paradox Illusion

jaa

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Whole Health Source: Is the "Obesity Paradox" an Illusion?

Stephan Guyenet has just wrote a post that makes some good arguments against the Obesity Paradox. He argues that the Obesity Paradox is the result of poor observational research methods that fails to account for disease causing people to go from overweight -> thin and fails to fully adjust for unhealthy habits, like smoking, that make people thin.

The fundamental problem with the obesity paradox is that it's based almost entirely on observational evidence, meaning that it doesn't come from controlled experiments that are better at identifying cause-effect relationships. And in this particular case, it's not hard to imagine ways in which observational methods could obscure the true relationship between body fatness and health. In other words, the obesity paradox could be nothing more than an illusion of the particular research methods that were used to identify it**.

How might this work? As an example, we know that illnesses such as diabetes and Alzheimer's disease often lead to weight loss (sometimes many years before diagnosis, meaning that you can't entirely eliminate the problem by excluding people with diagnosed disease). So if you're currently lean and sick, researchers may associate your illness with the lean category, even if you used to be overweight, and even if that excess fat caused your illness to begin with.

A similar phenomenon happens with cigarette smoking. Smoking causes weight loss, and it's also a fast track to illness and premature death. It's not hard to imagine how smokers might make leanness look a lot more dangerous than it really is. It's also not hard to imagine that some smokers don't accurately report their smoking habits, making it difficult to fully account for in studies.

He supports this with evidence from new research methods used that account for body weight history, and not body weight at time of diagnosis.

Yet a new research method developed by Andrew Stokes, assistant professor of global health at Boston University, promises to provide the clearest picture yet of the true relationship between body weight and health.

To minimize the pitfalls of traditional methods, Stokes looks not only at current body weight, but atweight history. He asks a simple question: how does a person's maximum attained weight associate with health outcomes? Weight is compared using the body mass index (BMI) scale, which corrects for the effects of height on weight.

Maximum weight should do a better job of capturing the effect of excess body fat on health, because traditional methods don't consider the possibility that a person might have previously carried more fat, and may have been exposed to its damaging (or protective) effects for many years. If this is true-- which seems fairly obvious to me-- then Stokes's method is a better test of the obesity paradox hypothesis than previous methods.

In 2014, I wrote about Stokes's first study using this method, which suggests that lean people have lower mortality levels than people who are overweight or obese (8). Recently, Stokes and his mentor Samuel Preston published two more papers on the subject, and they are much more detailed (9).

Using the maximum weight method, Stokes confirmed his previous finding that people who remain lean throughout life have the lowest risk of dying. Consistent with this, they also have the lowest risk of developing diabetes and cardiovascular disease. Both associations were substantial. Furthermore, people who already have diagnosed cardiovascular disease have a higher risk of dying if they're also obese, not lower. There is no paradox in these data, which is a good sign that we finally understand what's going on. It's also reassuring that his results align well with what we know from experimental studies in animals and humans.
 

Giraffe

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As an example, we know that illnesses such as diabetes and Alzheimer's disease often lead to weight loss (sometimes many years before diagnosis, meaning that you can't entirely eliminate the problem by excluding people with diagnosed disease).

As far as I know diabetes type 1 leads to rapid weight loss. Why would diabetes type 2 lead to weight loss?
 

tara

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I think there's a good point there about epidemiological studies having difficulty sorting out causal relationships.
Which allows room for doubt about claims based on such studies in either the direction of fat causing or fat protecting from disease.
 
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"The fundamental problem with the obesity paradox is that it's based almost entirely on observational evidence, meaning that it doesn't come from controlled experiments that are better at identifying cause-effect relationships."

Exactly.
 

tara

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"The fundamental problem with the obesity paradox is that it's based almost entirely on observational evidence, meaning that it doesn't come from controlled experiments that are better at identifying cause-effect relationships."

Exactly.
Related issues apply to the 'obesity epidemic' story.
 
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jaa

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[ moderator edit: threads merged ]

Stephen Guyenet just posted two new studies over at his blog that suggest the obesity paradox is not really a paradox at all, and is mostly based on confounders such as smokers and people losing weight when ill. He touched on this earlier this year when Andrew Stokes used a maximum weight method to try to diminish the effect of these confounders, and found that people who stay lean over their lives are at the lowest risk for all cause mortality. I posted about this here.

Whole Health Source: Two huge new studies further undermine the "obesity paradox"

I suggest reading Stephen's brief summary of the two studies.

tldr: Optimal BMI for healthy people seems to be ~20-22. Things don't start getting risky until you reach a BMI over ~27.
 
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Yes but. Losing weight itself through dieting doesn't mean the risk factors are any lower. The same causes of obesity are probably still present. Losing weight by itself may be worse for mortality rates. This is what nobody seems to get.
 

Tarmander

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Yeah it kind of messes up the causes and effects.

Lean people have the least mortality long term...okay, so if I am fat, then get liposuction to get rid of all the fat, then I will be the same as those lean people right? No, you're just a skinny fat guy with more problems now with all those lipo scars.

So say I am super fat and I go on an 800 calorie diet and lose it all and am lean, I am the same as all those naturally skinny people now right? Well no again, you are going to rebound hardcore and have all kinds of starvation issues.

BMI is not a good indicator of health. It is a tool to study populations, to do statistical analysis with. If you walk into your doctors office, and your BMI is 27 and the doctor says hey you need to get your BMI down to 22...well you should run...none of the ways they are going to suggest to accomplish this goal are going to be healthy. The correct question is: why are the lean people healthier?
 
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Yeah it kind of messes up the causes and effects.

Lean people have the least mortality long term...okay, so if I am fat, then get liposuction to get rid of all the fat, then I will be the same as those lean people right? No, you're just a skinny fat guy with more problems now with all those lipo scars.

So say I am super fat and I go on an 800 calorie diet and lose it all and am lean, I am the same as all those naturally skinny people now right? Well no again, you are going to rebound hardcore and have all kinds of starvation issues.

BMI is not a good indicator of health. It is a tool to study populations, to do statistical analysis with. If you walk into your doctors office, and your BMI is 27 and the doctor says hey you need to get your BMI down to 22...well you should run...none of the ways they are going to suggest to accomplish this goal are going to be healthy. The correct question is: why are the lean people healthier?

Yes. And I'm still thinking lean people often have many metabolic problems.
 
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jaa

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Yes but. Losing weight itself through dieting doesn't mean the risk factors are any lower. The same causes of obesity are probably still present. Losing weight by itself may be worse for mortality rates. This is what nobody seems to get.

Sure. But I think you're talking about the much smaller subset of overweight individuals who live a healthy life. Most do not. I'm also not convinced a decent percentage of that subset would not be better off with a little portion control and weight loss. Not starve yourself on kale shakes for bathing suit season portion control, more like cut back on the dense, somewhat void calories like sugar and coconut oil just a little.
 
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jaa

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Yeah it kind of messes up the causes and effects.

Lean people have the least mortality long term...okay, so if I am fat, then get liposuction to get rid of all the fat, then I will be the same as those lean people right? No, you're just a skinny fat guy with more problems now with all those lipo scars.

So say I am super fat and I go on an 800 calorie diet and lose it all and am lean, I am the same as all those naturally skinny people now right? Well no again, you are going to rebound hardcore and have all kinds of starvation issues.

BMI is not a good indicator of health. It is a tool to study populations, to do statistical analysis with. If you walk into your doctors office, and your BMI is 27 and the doctor says hey you need to get your BMI down to 22...well you should run...none of the ways they are going to suggest to accomplish this goal are going to be healthy. The correct question is: why are the lean people healthier?

While I agree, those are extreme examples.

Conversely, if you walk into your doctors office at age 19 with a BMI of 27 and want to be healthier and your doctor looks at your diet and lifestyle and makes a few tweaks so that you're eating healthier food while eating ~100kcal less a day and getting good sleep and exercise and managing stress well, I would be very surprised if your BMI didn't get down near 22 over the next few years and you weren't healthier than your 27 BMI self.
 
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jaa

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Brilliant post by Guyanet. Maybe he posted it as a response to Haiduts pro adipose tissue posts.

The Inflammatory Syndrome: The Role of Adipose Tissue Cytokines in Metabolic Disorders Linked to Obe

Yeah there are a bunch of things that go awry when you start packing on the pounds that go away when you lose the weight. This is not to say people should starve themselves at risk of worse metabolic derangement, or that everyone's past history is irrelevant and everyone's ideal BMI is 22, just that if you are overweight tweaking your lifestyle in a way that gradually lowers your weight is probably for the best.
 

Tarmander

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While I agree, those are extreme examples.

Conversely, if you walk into your doctors office at age 19 with a BMI of 27 and want to be healthier and your doctor looks at your diet and lifestyle and makes a few tweaks so that you're eating healthier food while eating ~100kcal less a day and getting good sleep and exercise and managing stress well, I would be very surprised if your BMI didn't get down near 22 over the next few years and you weren't healthier than your 27 BMI self.

Pretty much in agreement. So is he healthier because his BMI came down from 27 to 22 or because he made lifestyle changes? If the doctor had instead offered him liposuction to get down to 22 BMI, would he be as healthy?
 
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jaa

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Pretty much in agreement. So is he healthier because his BMI came down from 27 to 22 or because he made lifestyle changes? If the doctor had instead offered him liposuction to get down to 22 BMI, would he be as healthy?

Purely speculative, but I think both. I think the loss of fat that is likely a PUFA warehouse waiting to get oxidized is a benefit in and of itself. And the lifestyle changes that lead to weight loss have health benefits grander than simply losing the stored fat.

The process of liposuction may be a stressor that causes more harm than good, especially if the person getting one does not change their habits and just springs back to pre-lipo weight. That seems like the worst case scenario, and it may be better to just accept the weight. Conversely, if we can imagine a low-stress lipo-like procedure, it may be optimal for a person to undergo that surgery if they have a set of positive lifestyle changes they know they will implement and know will keep them at post lipo-like weight. This imaginary and idealized scenario would be very rare though, and for most people the process of stumbling through a number of strategies and keeping the useful ones as one gradually gets healthier is the best way to go.
 
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Guyenets studies don't use all cause mortality as far as I can see. This is far more important than cardiovascular caused deaths.
 

David PS

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A BMI over 27 is just a marker for living an unhealthy lifestyle. Liposuction to lower the BMI does not automatically change the underlying unhealthy lifestyle. Admittedly, if you lipo-away enough body fat you may make more likely that a person can walk continuously for 30 minutes; but there is no guarantee that extra walking will happen.

Liposuction can remove excess fat tissue. But people with diabetes should not confuse it in any way with bariatric surgery or traditional weight loss. Bariatric surgery (surgically enforced fasting) and traditional weight loss both help to improve insulin resistance, lower cholesterol, and lower blood pressure. It seems that liposuction does not. see https://intensivedietarymanagement.com/bariatrics-surgically-enforced-fasting-t2d-6/
 

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