What Obesity Paradox?

I’ve been following health and fitness news for many years now. One topic that has always puzzled me is the Obesity Paradox. To get us all up to speed, I asked Poe AI to explain the term.

The obesity paradox is a term used to describe the observation that, in some populations, individuals who are overweight or obese actually have better health outcomes than those who are of normal weight. This phenomenon has been observed in a number of chronic diseases, including heart failure, chronic kidney disease, and type 2 diabetes.

The paradoxical finding is that individuals who are overweight or obese have a lower risk of mortality compared to those who are of normal weight, despite the fact that being overweight or obese is a known risk factor for developing these diseases in the first place. This finding is paradoxical because it appears to contradict the widely held belief that maintaining a healthy weight is essential for good health.

The obesity paradox has also been observed in the context of longevity, with some studies suggesting that individuals who are overweight or mildly obese may actually have a lower risk of mortality than those of normal or low weight. However, this relationship between weight and longevity is complex and may vary depending on a variety of factors, such as age, sex, and overall health status.

How could this ever be true? How is it possible that all the behaviors that we know to lead to poor chronic health not have negative consequences with regard to longevity?

It turns out there may be no Obesity Paradox after all. It may have been a measurement problem. The article Excess weight, obesity more deadly than previously believed states:

Excess weight or obesity boosts risk of death by anywhere from 22% to 91%—significantly more than previously believed—while the mortality risk of being slightly underweight has likely been overestimated, according to new CU Boulder research.

Why such a huge discrepancy?

He (Ryan Masters) discovered that a full 20% of the sample characterized as “healthy” weight had been in the overweight or obese category in the decade prior. When set apart, this group had a substantially worse health profile than those in the category whose weight had been stable.

Of course. When people that have been obese develop chronic health conditions such as diabetes or cancer, they often lose weight before they die. They die with a lower BMI.

Masters pointed out that a lifetime carrying excess weight can lead to illnesses that, paradoxically, lead to rapid weight loss. If BMI data is captured during this time, it can skew study results.

Those deaths are then not counted against the high BMI group. Not only did the high BMI group purge many of the sickest from their numbers, but those individuals got added to the low BMI group.

image created with stable-diffusion XL

Healthy at any size?

In the last decade, we have been hammered with the message that one can be healthy at any size. This was mostly based on the Obesity Paradox, which if this research holds up, appears to be a measurement problem.

When re-crunching the numbers without these biases, he found not a U-shape but a straight upward line, with those with low BMI (18.5–22.5) having the lowest mortality risk.

While previous research estimated 2 to 3% of U.S. adult deaths were due to high BMI, his study pegs the toll at eight times that.

What if there is no obesity paradox?

Read the article. Let me know your thoughts. Common sense and my own bias (22.9 BMI) lead me to believe it is correct.


Add yours

  1. I know when I worked in cardiac surgery as a data manager that we talked about how overweight patients fared better after heart surgery. The thought was that the had more resources to draw on during recovery. But that’s just a theory we tossed around

  2. @Jillian – That makes sense. I suspect it is both true that excess weight leads to chronic conditions that shorten lives while at the same time having more weight could be beneficial in the final years.

    A family member started a diet in her 70s. She didn’t have much extra weight. I thought it was a bad idea since she didn’t have much muscle. She lost fat and muscle. Then she fell and suffered a serious injury that I suspect would not have been as severe at her heavier weight.

  3. I do suspect it’s a little more complicated than what the article suggests. I’m someone that was at one time influenced by Matt stone and Ray Peat. They present the idea that dieting and exercise are major stressors to the body and stress can often trigger disease. I think there is a kernel of truth to this. I think it’s overstated by Stone/Peat, but my own experience tells me that drastic dietary changes or physical activity changes can be quite taxing subjectively. It’s not hard to imagine this damaging some people. But they lose weight!

    I’ve also noticed that people that do lose weight through cutting calories, and keep it off often look much less healthy than when they were fatter, like they lose some glow.

    I guess my own opinion is that the body likes routine and things that its used to and that helps maintain and preserve health, long-term. I also think dieting and exercising are much more risky activities them most people realize.

  4. @Hs – It would be interesting to divide the healthy people into 2 groups. Those that needed to diet to achieve a good weight and those that didn’t. Since most dieters often lose and gain multiple times, I suspect this group might have a worse outcome that those that stayed at a healthy weight without gaining.

    As for looking less healthy, I think this is partially true. I did a post on that.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.