Amazon Halo Is First Wearable to Calculate Body Fat Percentage

halo app and band


Key Takeaways

  • Amazon has a new wearable health device called Halo.
  • The Halo measures body fat percentage, among other features.
  • Your body fat percentage may be able to help calculate your risk of developing obesity-related diseases.
  • Experts caution against fixating on one number, like body fat percentage, when thinking about your overall health.

Amazon just launched a new wearable health device called the Halo—and it promises to do a lot. Halo is Amazon’s first health wearable and, similar to smartwatches, is worn on the wrist. While it offers several features that aren’t revolutionary, like step counting and sleep monitoring, it also calculates the wearer’s body fat percentage, something no other wearable device does.

The band, which will retail for $64.99, measures body fat percentage through the use of an app and a smartphone camera. “Medical research has shown for years that body fat percentage is a better measure of overall health than just weight or body mass index (BMI) alone, but the tools that measure body fat percentage can be expensive or difficult to access,” an August 27 press release says. The Halo lets users measure their own body fat percentage at home and, Amazon says, the measurement “is as accurate as methods a doctor would use—and nearly twice as accurate as leading at-home smart scales.”

Experts say this feature can highlight a user's level of risk for developing metabolic health issues like type 2 diabetes and heart disease, but they caution against fixating on this percentage, exclusively.

“This number alone only tells you increased risk,” Keri Gans, RD, CDN, author of "The Small Change Diet," tells Verywell. “It doesn’t tell you actual blood pressure, resting heart rate, cholesterol levels, bone density, or any other labs and assessment needed for a health evaluation by a medical professional.”

Keri Gans, RD, CDN

I wouldn’t put that much stock in any one tool, wearable or not. There are so many other important factors that go into measuring a person’s overall health.

— Keri Gans, RD, CDN

How It Works

In order to calculate your body fat percentage, the device prompts you to pose for pictures of your front, back, and sides. The Halo app uses those photos—taken with a smartphone camera—to analyze the physical properties of your body, including your body shape and distribution of fat and muscle. It then analyzes regions of the body that are known to be “hot spots” for measuring body fat, like the torso, thighs, and middle of the back.

The device then generates a 3D model of your body and gives you your body fat percentage. It also creates a "body model slider," which allows you to see what you would look like if your body fat changed.

Amazon tested the readings against a dual-energy X-ray absorptiometry (DXA), “which is considered the clinical gold standard for body composition,” as well as a wide range of body types, ages, genders, and ethnicities, Maulik Majmudar, MD, a cardiologist and principal medical officer for the Halo, explains in an Amazon blog post. The company plans to continue to improve the feature over time.

What This Means For You

Amazon’s new Halo wearable measures body fat percentage, but experts aren’t sure how much this feature can tell users beyond their risk of developing certain diseases.

What Is Body Fat Percentage?

"It is very helpful to look at body fat percentage in conjunction with one’s weight status to determine if one’s weight may be in excess,” Fatima Cody Stanford, MD, an obesity medicine physician at Massachusetts General Hospital and an instructor of medicine and pediatrics at Harvard Medical School, tells Verywell.

How Is Body Fat Percentage Calculated?

Body fat percentage is calculated by dividing a person’s total fat mass by their total body mass. Then multiply by 100.

There is a bit of confusion on what body fat percentage is considered OK, Stanford says. Factors like gender and whether a person is an elite athlete matter, she says, but the following chart by the American Council on Exercise (ACE) is commonly used:

ACE body fat percentage guide

“However, you will see other charts,” Stanford says. “We need to have a standard measure by which we evaluate one’s body fat to make it very helpful to the general population.”

Can Measuring Body Fat Percentage Help Treat Obesity?

Body fat percentage can help give a deeper understanding of a person’s health, Gans says. “The higher the percentage of an individual’s body fat, and specifically a higher waist circumference, may put them at a higher risk for certain diseases,” she says. While BMI is often used to determine obesity and overweight, it’s “not the most accurate tool to use since it doesn’t take into consideration an individual’s body fat or muscle tone—both important for assessing a person’s health risk,” Gans says. 

If someone has a high amount of excess fat, “that may point to a higher risk of metabolic health issues such as type 2 diabetes, heart disease, and non-alcoholic fatty liver disease,” Stanford says. From there, experts can make recommendations, like adding cardiovascular and strength training activities to try to address the excess fat and reduce health risks, along with eating a healthy diet.

A person’s body fat “does not change dramatically over time,” Stanford says. "[But] there can be gradual changes that accumulate over time that lead to an excess amount of fat."

For now, Stanford is unsure how body fat percentage can reliably be used to determine a person’s overall health.

“Since there are no guidelines in place currently that utilize body fat percentage, I think that there may be a lag in the medical industry being able to utilize this information in a way that is standardized,” she says. “However, I can see that guidelines may change to accommodate knowledge of one’s body fat to guide therapeutic treatment for diseases such as obesity.”

On a personal level, Gans encourages people not to get too fixated on their own body fat percentage. “I wouldn’t put that much stock in any one tool, wearable or not. Nor would I want any individual to get fixated on a single number,” she says. “There are so many other important factors that go into measuring a person’s overall health and that needs to be remembered.”

By Korin Miller
Korin Miller is a health and lifestyle journalist who has been published in The Washington Post, Prevention, SELF, Women's Health, The Bump, and Yahoo, among other outlets.