How your weight can affect your RealAge

A birthday isn’t always the most accurate measure of one’s age. That’s because there are more factors than a date on the calendar that influence how old (or young) you really are.

RealAge is one scientifically backed measure that relates your biological health to your calendar age. It does so by considering a wide array of health details, including your lifestyle habits, chronic health problems, genetics, and even your weight.

Keith Roach, MD, is an associate professor in clinical medicine in the division of general medicine at Weill Cornell Medical College and New York Presbyterian Hospital, and a co-creator of the RealAge Test. Read on to learn Dr. Roach’s insights on how weight can affect your body’s true age—and what you can do to live longer and more healthfully.

“RealAge is a measure of your overall health compared to everybody else,” says Roach. “So if you’re the average person, your RealAge will be the same as your chronological (or calendar) age. But if you’ve been healthy and taken care of yourself, your RealAge will be younger than your chronological age.”

And the flip side? “If you’ve made poor choices, have health problems, or have been unlucky with your health, your RealAge will be older than your chronological age,” he says.

There are more than 100 factors that can influence a person’s RealAge. Some may seem obvious, like smoking, while others may not, such as sitting all day or being lonely. One thing’s for sure, says Roach: Many of the factors that affect one’s RealAge also play a role in one’s weight.

It’s well known that obesity is linked to several health issues, including heart disease, hypertension, and type 2 diabetes, all of which can significantly impact your RealAge. For example, poorly managed diabetes can, in effect, make you 10 years older than you really are. High blood pressure and high cholesterol can add eight years and six years, respectively, says Roach. And it’s not just obesity that can boost RealAge. Having excess belly fat, in and of itself, makes your RealAge older.

While it may not be a surprise that being overweight may contribute to health issues and make your RealAge older, being significantly underweight can have similar effects on your life expectancy.

One study published in 2018 in The Lancet Diabetes & Endocrinology looked at the health records of more than 3.6 million people age 16 and over in the UK, including nearly 2 million non-smokers, using body mass index (BMI) as a measure of weight. (Although it is used commonly to indicate an individual’s level of overweight or underweight, BMI is only one measure used for this purpose and is not always a perfect measure of one’s overall health.) Compared with those non-smokers who had a healthy weight (measured as a BMI between 18.5 and 24.9), the life expectancy of obese people (BMI of 30 or greater) from age 40 on was 4.2 shorter for men and 3.5 shorter for women. Surprisingly, the life expectancy for those considered underweight (with a BMI less than 18.5) was even shorter: 4.3 years less for men and 4.5 years for women.

Why might this be the case? Someone who is very thin may be struggling with a major health problem such as cancer, fighting an addiction to drugs or alcohol, or experiencing an eating disorder such as anorexia. In these scenarios, it’s likely that their disease is reducing their life expectancy and not their weight, says Roach.

So what’s an ideal weight when it comes to RealAge? “The best thing is to be in the middle—not quite overweight as most Americans are, but not excessively thin, either,” says Roach.

One large review of studies published in 2013 in the Journal of the American Medical Association (JAMA) raised eyebrows when it found that people who were overweight, but not obese, lived longer compared to normal weight folks. While more research is needed to better understand findings like these, Roach recommends the following to his patients: “If you are just a little overweight with a BMI of 26, 27 or 28, I wouldn’t tell you to lose weight. But if you have a BMI of 35 or more, you need to lose weight.”

Unless you are significantly overweight, perhaps the best advice is to focus on cultivating an overall healthy lifestyle rather than a particular number on the scale. Eating a healthy diet can make your RealAge four years younger. Regular exercise also increases longevity. “Going from sedentary to fit can easily make your RealAge five or six years younger,” says Roach.

But the single most important thing you can do to lower your RealAge? Quit smoking.

“Smoking adds about 12 years to your RealAge,” Roach says. “Many people say they don’t want to quit because they will gain weight. But there is no amount of weight you can gain that can counteract the benefits of quitting.”