For decades, people who wanted to be fit had only a few ways to track their progress.

Stand on a scale, measure their waist, and calculate their body mass index (BMI).

In the past few years, technology has expanded the number, complexity, and precision of those measurements.

The latest way to gauge the effectiveness of your fitness regimen is to stand in front of, or step inside of, a 3-D body scanner.

Two scanners with growing popularity are the mPod, housed in a secure, automated booth, and the Fit3D ProScanner, which uses a portable scanner tower with connected turntable.

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It’s like being at the airport

The technology is familiar to anyone who's raised their arms overhead inside an airport security scanner.

Scanners benefit from the innovations found in the motion-sensing technology of Microsoft's Kinect, part of the Xbox One introduced in 2011.

The mPod was designed by Dipra Ray, Melody Shiue, and Andy Wu, who met as university friends in Australia. Ray and Wu majored in business and finance, Shiue in industrial design.

The company they founded, mPort, has partnered with LA Fitness to install 670 units in its clubs in the United States. Following the initial rollout in Orange County, Calif., the company is now installing mPods in other cities.

The mPod user steps into a photo booth-sized pod and stands still in one place while several sensors capture highly accurate body data without the user having to move. In a few minutes, the scanner produces a 3-D image that shows real-time changes achieved through different diets and fitness regimens.

“The mPod is 100 percent automated,” Mehul Dave, mPort’s chief marketing officer, told Healthline. “The user does not require another person to help them. You interact only with the machine. The mPod has an audio, visual, and touch interface. It talks to you and you talk back with your hands.”

The mPod uses noninvasive infrared technology, equivalent to what comes out of a television remote control, and is safe to use for everyone including pregnant women, he said.

“The unit maps more than 200,000 data points to measure your individual body shape,” Dave added. “Then it sends the information to the mPod mobile app, creates a 3-D image, or avatar, with data on all body and health measurements, and what they mean. It also describes the levels of risk you face.”

The mPod records height, weight, biceps, chest, narrow waist, hips, mid-thigh, knees, calves, shoulders, and neck. It also measures BMI, body fat percentage, fat-free mass and percentage, waist-hip ratio, waist-height ratio, basal metabolic rate, ideal weight range, and target heart rate for exercise.

Dave and his colleagues finished their prototype in May 2013, and attracted investors four months later. By June 2016, they had signed the contract with LA Fitness clubs.

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Seeing the changes

The mPort focus is direct use by the customer in a shopping center or a club.

The mPod design offers security and comfort in a public place, Dave said. The app extends the usefulness of the scan by allowing users to access and use their data anytime to pursue health and fitness goals.

While mPort’s founders first conceived of their scanner as a way for users to measure themselves before buying clothing online, Greg Moore — the founder and chief executive officer of Fit3D in Redwood City, Calif., and creator of the ProScanner — was inspired by his mother, Lynne.

In an interview with Healthline, Moore said, “After trying for several years to shed some unwanted pounds, my mother hired a trainer and a nutritionist and started on a very healthy lifestyle. She mixed healthy eating with high-intensity interval training and cardio exercises. She was building muscle while shedding fat. So when I'd see her every few months, I could see that she fit inside of her old body.”

Lynne became increasingly demotivated because her weight seemed to change so minutely, he said.

With a background in fitness, he knew her body was getting more lean and dense, but she didn't have a way to evaluate her progress. She finally gave up.

A computer engineer, Moore was a member of the invention team at Sportvision, which provides data and analytics for MLB teams. He drew on that experience, beginning in 2010, “to solve my mom’s problem with motivation.”

The Fit3D ProScanner user stands on a raised circular platform that makes one 360-degree rotation while an infrared camera on a nearby aluminum stand records information and relays it to a connected laptop.

The ProScanner captures about 1,200 “depth” images on a body and combines them to create a full 3-D avatar of a human body, Moore said. The unit extracts more than 350 of those measurements to produce proprietary and university research-backed wellness metrics.

“The data is finally presented to users and their coaches through the cloud-based Fit3D web platform,” Moore said. “Users can see scans and stats, compare them to past scans, and see a crazy amount of data about their bodies.”

Fit3D sells, leases, or rents ProScanners to a spectrum of businesses to enhance their customer experience, Moore said. Clients include health insurance companies, hospitals, health clubs, weight loss centers, fashion brand shops, and custom-made men’s suit shops.

Moore said user feedback has helped to improve the ProScanner.

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Do 3-D images help someone lose weight?

James Shapiro, a certified personal trainer and president of New York City-based Primal Power Fitness, has watched the tech boom in fitness over the past decade.

“I've seen how impactful wearable tech has been for data tracking,” he told Healthline. “But this turn into 3-D body scanning is incredible.”

“When I try to create a blueprint for someone, I want to know every possible detail,” he added. “This boils down to nutrition, sleep habits, hydration levels, stress levels, and more. These small variables matter because it can be the difference of a couple points of body fat, or levels of performance.”

Clients benefit from the wealth of recorded scan data.

“Having these small details in a physical representation offers a picture the client can believe in and understand when it comes to body composition,” Shapiro said. “A scan removes the margin of error that bio-electric impedance tests [which measure body fat in relation to lean body mass] have, and that has significant reliability. On a larger commercial scale, scans can be the best thing that can happen to personal training.”

Although Shapiro and his colleagues have no experience yet with 3-D scanning, he has a keen interest in the technology.

“When you want to deliver a quality service, you want to provide the best information to back up your statements or claims,” he said.

This would be more important for his clients who wish to considerably improve body composition and would benefit from the detailed 3-D images, he added.

“A scan would offer a significant physiological boost to clients, who would be able to see that their sweat and tears were showing concrete results,” he said.

Shapiro said the only real drawback to 3-D scanning would be that either the trainer or the client could misinterpret the information and believe they could achieve “spot” reduction.

“Spot reduction is the belief that you can reduce a specific area of the body through extensively training only that part,” he said. “This might lead to unclear expectations and loss of motivation due to a lack of results.”