Obesity can Raise the Risk of Death More Than Believed

Excess weight or obesity boosts the 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. These findings, published in the journal Population Studies from new CU Boulder research, could counter the prevailing wisdom that excess weight boosts mortality risk only in extreme cases.

The statistical analysis of nearly 18,000 people also shines a light on the pitfalls of using body mass index (BMI) to study health outcomes, providing evidence that the go-to metric can potentially bias findings. After accounting for those biases, it estimates that about 1 in 6 U.S. deaths are related to excess weight or obesity.

Existing studies have likely underestimated the mortality consequences of living in a country where cheap, unhealthy food has grown increasingly accessible, and sedentary lifestyles have become the norm. This study is beginning to expose the true toll of this public health crisis.

Challenging the Obesity Paradox

While numerous studies show that heart disease, high blood pressure, and diabetes (which are often associated with being overweight) elevate mortality risk, very few have shown that groups with higher BMIs have higher mortality rates.

The conventional wisdom is that elevated BMI generally does not raise mortality risk until you get to very high levels and that there are some survival benefits to being overweight. BMI, which doctors and scientists often use as a health measure, is based on weight and height only and doesn’t account for differences in body composition or how long a person has been overweight.

To see what happened when those nuances were considered, researchers mined the National Health and Nutrition Examination Survey (NHANES) from 1988 to 2015, looking at data from 17,784 people, including 4,468 deaths.

They 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.

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Meanwhile, 37% of those characterized as overweight and 60% of those with obese BMI had been at lower BMIs in the decade prior. Notably, those who had only recently gained weight had better health profiles. Looking at differences in fat distribution within BMI categories, they also found that variations made a huge difference in reported health outcomes.

Exposing Obesity as a Public Health Problem

Collectively, the findings confirm that studies have been “significantly affected” by BMI-related bias. Contrary to previous research, the study found no significant mortality risk increases for the “underweight” category.

While previous research estimated that 2 to 3% of U.S. adult deaths were due to high BMI. Researchers hope that the study will alert scientists to be “extremely cautious” when making conclusions based on BMI.

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But they also hope the work will draw attention to what he sees not as a problem for individuals alone to solve but rather a public health crisis fueled by an unhealthy or “obesogenic” environment in the U.S.



Source-Eurekalert