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How does your weight affect your longevity? Here's what science has to say.
By Lani Akingbade — Written on Apr 16, 2021
This may be the first time you hear that carrying around some extra weight may actually be good for your health.
While the connection between health, obesity, and weight has been the subject of ongoing debate (and will likely continue to be so) for a long time, one study found that there may just be a positive relationship between body fat and life expectancy.
Since 2003, researchers at the UC Irvine Institute for Memory Impairments and Neurological Disorders (UCI MIND) have been conducting a still-ongoing study — referred to as "The 90+ Study" — to gain greater insight into the role of lifestyle, diet, health, and other factors play in longevity.
While their stated goal was understanding what allows people to live to age 90 and beyond, their findings uncovered surprising information about longevity among fat people.
And their findings deliver insight into why fat people live longer.
Over the course of their in-depth look at the lifespan of more than 1,600 people belonging to the generation the team calls "the oldest old," one particularly surprising finding emerged.
People who were overweight in their 70s lived longer than people who were normal or underweight.
This is good news considering that the most recent statistics show an estimated 1 in 3 adults in the U.S. are considered to be overweight.
But with that being said, there is also no doubt that extreme obesity carries an increased risk of illness and even death.
Do skinny people live longer? According to a study from the Lancet Diabetes and Endocrinology, life expectancy is shortened by 4.3 years for obese men and 3.5 years for obese women. However, life expectancy was also shortened for underweight men and women, with 4.3 years less for underweight men and 4.5 years less for underweight women.
If a person has over 31 percent body fat, the person is not considered healthy. It's normal to have a bit of fat or "chubbiness," but when your BMI is over 30, you are considered obese, which is a big difference from being overweight.
Do overweight people live longer?
The findings from "The 90+ Study" align with a 2013 study out of the Journal And Medical Medical Association, which found that being slightly overweight lowers your risk of death.
The researchers focused on body mass index and on death rates, and looked at nearly 300 studies around the world. The studies included almost 3 million people and over 270,000 deaths. The people in the overweight BMI category lived longer than those in the normal weight category, with a 6 percent lower risk of dying.
Other studies have found that older people over the age of 70 who packed on extra pounds have lived longer than those who don't because, according to lead researcher Leon Flicker, PhD, of the University of Western Australia, your body mass index (BMI) weight isn't useful after age 70.
Authors of "The 90+ Study" used the following terminology in keeping with that of the National Heart, Lung, and Blood Institute:
Underweight: BMI of less than 18.5
Normal weight: BMI of 18.5 to less than 25
Overweight: BMI of 25 to less than 30
Grade 1 obesity BMI of 30 to less than 35
Grade 2 obesity: BMI of 35 to less than 40
Grade 3 obesity: BMI of 40 or greater
"Relative to normal weight," they explained, "both obesity (all grades) and grades 2 and 3 obesity were associated with significantly higher all-cause mortality. Grade 1 obesity overall was not associated with higher mortality, and overweight was associated with significantly lower all-cause mortality."
In layman's terms, this means that people in the two highest categories of obesity have the shortest life expectancy of all, those who are "overweight" have the longest life expectancy of all, and people who are just slightly obese are no more likely to have a shorter life span than anyone else.
What is the average life expectancy of an obese person?
There's a difference between slightly overweight and overweight, and that is a difference in the number of years you have left; a body cannot handle obesity for a long period of time.
If someone is severely obese , that could mean a higher risk to their life expectancy. The average age of death is around 75-80 for an obese woman and around 70-75 for an obese man. For an obese woman who smokes, the average age of death is around 70-75, and for an obese man who smokes, it's 65-70.
Does being overweight shorten your lifespan?
There have been countless studies on the effect of obesity and death rate, and for almost all of the results in these studies, a decrease in life expectancy was associated with being overweight or obese.
People who are obese, more likely severely obese, with a BMI that's greater than or equal to 40, could have their life expectancy reduced by as much as 20 years for men and 5 years for women.
The reduction in life expectancy is great for men if they are predominantly obese in the abdominal area, and it's greater for women if they have a biologically higher percent of body fat.
Why would being somewhat overweight potentially increase longevity?
The right amount of fat can help with the body's insulation, body function, as well as vitamin and personal shock absorption. And with life being so unexpected, having that extra body fat to insulate us during times when we encounter scary situations can be a good thing.
Dr. Steven Hymsfield of the Pennington Biomedical Research Center in Baton Rouge, LA, told NPR that, in certain instances, having a couple of extra pounds may also help you live longer because the additional weight can potentially provide some protection against certain serious injuries.
"If you fall and you fall on vulnerable bone, like the hip, having a little extra fat there might protect you from hip fracture," Hymsfield said, adding that if an illness leaves you unable to eat, extra body fat could be useful.
Regardless of your own particular body type, it's hard to argue with the fact that the best way to guarantee a healthy, long life is through a healthy lifestyle that includes a heart-smart diet and lots of physical activity so you don't need to focus on weight loss later in life.
Lani Akingbade is a regular contributor to YourTango who focuses on lifestyle and entertainment news.
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Editor's Note: This article was originally posted on March 27, 2018 and was updated with the latest information.