By Maryann Tomovich Jacobsen, MS, RD
If you haven’t heard, a recent study published in the Journal of the American Medical Association has turned conventional wisdom about health and weight on its head. Well, sort of.
This very ambitious study, which reviewed almost 100 studies, found that people who were defined overweight by standard BMI standards (25-30) had a lower chance of dying than those with lower or higher BMIs.
So I did some digging to get to the bottom of it.
The study details
“There is a lot of confusion on this topic with studies not always using standard BMI-index standards,” says Katherine Flegal, PhD, a distinguished consultant with the CDC’s National Center for Health Statistics. “Our goal with this study was to take standard BMI categories and apply it to all the research.”
Flegal is referring to the National Heart, Lung, and Blood Institute’s BMI categories of underweight (<18.5), normal weight (18.5-<25), overweight (25-<30), and obesity ( ≥30). Grade 1 obesity was defined as a BMI of 30 to less than 35; grade 2 obesity, a BMI of 35 to less than 40; and grade 3 obesity, a BMI of 40 or greater.
After pooling all the research together and using the standard categories, Flegal and her colleagues found that overweight individuals were 6% less likely to die compared to those in the normal weight category. Those considered obese by the standards were about 18% more likely to die compared to the normal weight category. That being said, class 1 obesity wasn’t found to be significantly related to high all-cause mortality.
Although Flegal said she was surprised how consistent the findings were from study to study, she isn’t trying to create a message or key point from the results. “There is no message,” she says. “it’s just an objective review of the literature.”
Some theories as to why
This is not the first research to show health benefits from carrying extra weight. There is something researchers call the “obesity paradox,” showing that once someone is diagnosed with certain diseases such as heart failure, hypertension, kidney disease and coronary artery disease, those with extra weight have better survival than those at normal weight or who are underweight.
It is thought that the extra weight helps by providing additional fuel needed to help fight disease, seeing as in some cases, like with heart failure and kidney failure, patients often lose weight. A normal or underweight person would have little reserves in these cases.
“Doctors tend to treat obese individuals according to standards,” Flegal adds as another possible theory. “And they often present earlier with health conditions, getting treatment sooner.”
Is there a take-home message?
A limitation of this study is it did not measure disease, quality of life or fat distribution. We don’t know much about the type of lifestyles the peopled led, which would likely impact the results. Flegal makes the important point that “BMI is not a health category, it is a weight category.”
As I’ve blogged about before, we cannot assume someone’s health from their weight. I believe we’ve spent an enormous amount of energy focusing on weight in this country and we’ve missed the point of good health. And that it doesn’t have to come in just one size.
There are many people this time of year that want to shed those extra 5, 10 or 20 pounds. But I say look at all the health factors. Are you getting good sleep? Do you eat well? Exercise? Is your blood pressure normal? I say focus on those things, and not weight.
What do you think about this latest news? Let us know us know in the comments.