Carrying a few extra pounds as you get older isn’t necessarily unhealthy. In fact, according to a new meta-analysis, you might actually live longer than someone who’s underweight. I actually came to this exact same conclusion 30 years ago.
My Ph.D. dissertation research and my early investigations at the National Cancer Institute were among the first to find that adult diet and adult body weight don’t affect disease risk as strongly as you might be led to think.
In the ensuing 30 years, many other studies showed carrying a little extra weight doesn’t increase disease risk (even cancer risk). In fact, it may even protect you a little as you get older.
In this new meta-analysis, Australian researchers wanted to see whether body mass index (BMI), specifically, affected all-cause mortality risk in older adults. They analyzed 32 pertinent studies published between 1990 and 2013, which included BMI data on nearly 200,000 adults over age 65 years. They classified “normal” as having a BMI between 23 and 24.
As you may know, BMI is an indirect measure of excess body weight. It uses a simple formula: weight (in kilograms) divided by height (in meters) squared. But as I’ve often said, and as this study shows, it’s not the be-all, end-all measure of health.
In fact, according the analysis, slightly underweight men and women with BMIs of 21 to 22 actually had a 12 percent greater mortality risk. And men and women with even lower BMIs of 20 to 21 had a 19 percent greater mortality risk. Even after the researchers accounted for subjects who died young or had a preexisting disease, the mortality risks for these leaner adults stayed high.
Now, here’s an interesting point…
As I said earlier, the researchers in this study defined normal as 23 to 24. But this definition is very narrow. In fact, the Centers for Disease Control (CDC) define “normal” much more broadly, calling levels even as low as 18.5 “normal.” (The CDC’s broader definition perhaps displays a politically correct prejudice to being underweight, even if unhealthy.)
So, now, let’s look back at the analysis data.
We have people with BMIs of 20 to 21 (well within the CDC’s definition of “normal” body mass) and they have a significantly higher mortality rate. But what about someone with a BMI of 18.5, at the lowest end of the CDC’s defined normal range? This study didn’t analyze BMI levels quite that low. But if this same pattern continues, that person with “normal” body mass might increase their mortality rate by as much as 25 to 30 percent!
By comparison, overweight men and women in the study did not increase their mortality risk. Not one iota.
Mortality risk only began to creep up in overweight men and women with BMIs higher than 33. Of course, many experts lump overweight and obese men and women together. But it turns out there is a world of difference.
As an anthropologist, I know that a little extra body weight, especially as you age, can have a protective benefit. And this fact has always been true.
And it’s especially true when it comes to women.
Women naturally have a little more fat tissue than men. They need it for normal reproductive and hormonal function. In fact, during the 1970s, Harvard researcher Rose Frisch demonstrated that women who don’t have enough fat actually stop ovulating. And they effectively become infertile. Dr. Frisch made these observations by studying women who engaged in extreme diets and/or exercise regimens.
But in the past 50 years, there has been a shift in cultural and medical perceptions that favor being underweight. Today, many people think someone with a rounder figure is undesirable…and unhealthy. This misconception has caused untold misery and suffering. And probably even an untold number of deaths, according to the new analysis.
In Shakespeare’s play, Julius Caesar said, appraising his conspirators, “yon Cassius has a lean and hungry look; such men are dangerous. I’ll have about me men who are fat… sleek-headed men, such as sleep at night.”
Bottom line?
Try not to lose any sleep over shedding those last few extra pounds. Especially as you get older. You’ll live longer, as Caesar probably would have if he’d kept counsel with someone with a higher BMI.
Sources:
1. “BMI and all-cause mortality in older adults: a meta-analysis,” Am J Clin Nutr March 2014