Kim Kardashian Shared the Results of Her Full Body Scan, But What Even Is That?

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It's not unusual for Kim Kardashian to share a glimpse at her health and wellness pursuits with her followers on social media. Most recently, the reality TV star and entrepreneur posted her most intimate photo yet: an image of a full body scan.

On Wednesday, Kardashian detailed her experience of getting a full body scan from the company BodySpec on her Instagram Stories, including a few snaps of her results. If you caught the posts on her Instagram, you saw an X-ray image of her body, along with numbers and percentages. In her initial posts, she showed off her bone density score and body fat percentage, claiming she landed in the "athlete category" based on her results.

Curious what the purpose of a full body scan is and what Kardashian's results mean? Keep reading for a breakdown of the health care tool. Related: Kim Kardashian's Drastic Weight Loss for the Met Gala Is Concerning

What is a full body scan?

Kardashian got a DEXA (dual-energy X-ray absorptiometry) scan, explains Alyssa Olenick, Ph.D., C.I.S.S.N., C.F.L.1., an exercise physiologist. "This is a low dose X-ray that can tell you about how much muscle, bone, and fat mass you have," she says. "Because it is an X-ray, it is able to segment out your body parts and where fat and muscle is distributed and how much. It also tells you about your bone density, which is an important marker of bone health and [is] important as you age," she adds. FYI, bone density refers to how strong and flexible bones are, according to the Mayo Clinic. With bone loss (for instance, when caused by osteoporosis), bones become weaker and are at higher risk for fractures.

The total makeup of the tissues in your body, including muscle, bone, and fat, is referred to as your body composition. It's important to note that body composition is just a ratio of fat and non-fat mass (muscle and bone), says Olenick. That means that "sometimes a 'higher body fat' may not be reflective of having 'too much fat' but 'too little muscle,'" she explains.

The results of a full body scan differ from another ratio you might be familiar with called the body mass index (BMI), which is influenced by societal and racial biases. It suggests ideal health measurements based on height and weight ratios from a sample of white European men. DEXA scans are calculated by comparing the average values of people of the same age and gender from a large national database, says Olenick.

Additionally, BMI isn't an accurate measure of health, since it's based solely on height and weight, without accounting for bone density, muscle mass, and fat mass. That means "many muscular athletes have overweight BMIs but may be very lean in a body composition scan," says Olenick. "Or someone could have a healthy BMI but need to build more muscle," she explains." A body composition scan "is a more honest and better look at your body," says Olenick.

Why would someone get a DEXA scan?

Getting a full body scan can tell you important health information about your bone density. Anyone who is able to access and afford a DEXA body scan should get one, especially women and trans individuals, says Olenick. That's because when women or previously menstruating individuals go through menopause, their estrogen levels drop, which can decrease bone density. It's one of the reasons women have higher risk of bone disease than men, explains Olenick. "Having a baseline of knowing your bone density is especially important as you age or if you go through menopause and become at higher risk for osteoporosis," she adds.

This type of scan is also helpful because it shows people how much muscle tissue they have, which is an important marker of health, says Olenick. Having muscle mass "can prevent muscle loss and frailty" as you age, she explains. It also helps improve your quality of life and is important for metabolism, glucose regulation, and insulin resistance, adds Olenick. (See: Jane Fonda On the Importance of Staying Strong as You Age)

In addition to fat free mass (bone, connective tissue, organ tissue, and muscle tissue), a DEXA body scan also indicates fat mass. Fat mass "is the adipose tissue (body fat) where your body stores fat cells within the body or other stored fat." While fat percentage is one piece of the puzzle here that can give you a greater indication of overall health, it's important not to fixate on numbers. "People are all also built differently, and the way a certain body fat percentage looks on someone may look different on someone else if they store fat differently," says Olenick.

DEXA scans are especially helpful for endurance athletes and anyone who has undergone a period of "extreme under-eating or dieting," says Olenick. That's because these situations put a person at higher risk of bone fractures.

What do the results from a DEXA scan mean?

Kardashian shared that her bones are stronger than 93 to 97 percent of people, based on the results of her scan, which included a "Z-score" of 1.3 out of two. "A bone density Z-score is your score compared to the average values of people of your same age and gender from a large national database," says Olenick, who confirms Kardashian seems to have a healthy bone density. "I'm actually really happy to see that Kim has and is promoting a really healthy bone density in women," says Olenick. "Having a higher bone density can help prevent stress fractures or major fractures as you age or help with bone loss that comes with menopause or aging or with restrictive diets," she continues.

The Skims founder also shared that she has 18 percent body fat (down from 25 percent last year), putting her in the "athlete category," according to her Instagram Story. "Eighteen percent body fat is fairly lean for a female, but it's also important to note her previous body fat of 25 percent was also perfectly healthy and also considered 'athletic' depending on who you ask," says Olenick. "Typically athletes are leaner or have more muscle tissue than people who are less active, depending on the type of sport they engage in, but this isn't always true," she adds. "People can have a higher body fat percent than Kim or this category and be athletic or an athlete."

While a full body scan can tell you helpful information about your health, isn't helpful to compare your results to others, including celebrities. "Body composition scans are just a ratio at the end of the day," says Olenick. "It's important to not put too much weight in these numbers," she adds.

So, if you have access to a full body scan, it might be able to tell you useful information about your body composition. But overall, results from this type of test won't offer a complete picture of your health. If you have more specific questions about your own body composition, it's always best to speak with your health care provider who can offer personalized advice.