Are the Mortality Risks of Excess Weight Underestimated?

How dangerous is obesity? For years we’ve seen studies & headlines attaching risk to excess weight, but even those may have been too much of an underestimation of the danger in terms of mortality. According to new research by Andrew Stokes, a doctoral student in demography and sociology at the University of Pennsylvania, the obesity-related mortality risks presented in many studies may be underestimated.

Stokes said that in previous studies, the ‘normal weight’ BMI category combines data from low-risk, stable-weight individuals with high-risk individuals who have experienced weight loss. But Stokes used individuals’ highest Body Mass Index (BMI) in life to predict mortality rates. The use of weight histories allows for separation of the two groups and redefines the reference category as people who were a consistently normal weight throughout their lives.

Using large national health surveys and the National Death Index, he found that the percentage of mortality attributable to excess weight in adult non-smokers, ages 50-84, was 33 percent when assessed using maximum BMI. The comparable figure obtained using BMI at the time of survey was much smaller–just 5 percent.

Stokes said “Using BMI at the time of the survey to assess the mortality risks of overweight and obesity is problematic, especially in older populations, because slimness can be a marker of illness.” The results provide evidence that prior research may underestimate the impact of obesity on levels of mortality in the United States. Although Stokes’ research indicates a higher risk of mortality associated with obesity than previously reported, there is a significant benefit to losing weight, which is why primary care physicians have been urged to treat obesity like any other serious disease.

We spoke with San Diego weight loss surgeon, Sunil Bhoyrul, MD, about the study. He said, “This is a fascinating article that shows us how BMI alone is a poor measure of health.  According to a recent article in JAMA, and in keeping with our own observations over decades of clinical experience, a much better determination of health is the amount of fat around your organs (visceral fat), which is also similar to the fat around your mid section.”

Dr. Bhoyrul explained that we need to get beyond BMI, to assess each individuals health and wellness thoroughly by using the best scientifically validated tools to measure weight, body fat, metabolism, and fitness.  “Using all these data (in combination with current measures of health such as blood pressure, blood sugar, etc), we are able to more accurately predict the risk of long term health problems, and personalize a health and wellness strategy to the needs of the individual patient.  If that strategy includes surgery, then the type of surgery, as well as the type of follow up care, should take into account these modern clinical data,” Bhoyrul concluded.

Related Reading: Recalculating the Obesity Epidemic

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