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Fit3D uses the Mifflin St. Jeor formula to calculate BMR.

There are multiple formulas used to calculate BMR. Nowdays, the Mifflin-St Jeor equation is believed to give the most accurate result and it's what we use in this calculator.

This BMR formula is as follows:

BMR = (10 * weight / 1kg + 6.25 * height / 1cm - 5 * age / 1 year + s) kcal / day, where s is +5 for males and -161 for females.

Fit3D’s proprietary body fat algorithm is our own, based off data we’ve gathered with our medical research partners that use both the ProScanner and a DXA body fat machine. Fit3D body fat is based off anthropometric measurements of more than 1,000 scans for which they also have DXA data. The Fit3D body fat algorithm correlates with DXA body fat data. Why correlate to DXA? Aside from costly MRI scans, DXA scans are the gold standard for body composition data, common in medical research facilities, yet not easily accessible for consumers.

The chart below shows a fantastic breakdown of wellness ranges broken down by gender and age. This chart was created directly from our partners at DexaFit.

Your body fat percentage is your fat mass divided by total mass. Lean mass is made up of everything that is not fat, your muscles, bones, and organs. So, if you’re noticeably decreasing your total mass, while your fat mass stays the same, your body fat percentage will increase.

Even if your fat mass is decreasing, total mass is decreasing faster, resulting in an increase of body fat percentage.

Clinical anthropometrics and body composition from 3D whole-body surface scans

This study was published in the European Journal of Clinical Nutrition. We revised the algorithm a bit from here and will re-publish with the new algorithm through our collaboration with Mount Sinai Hospital when it is released.

Yes. We have no way of knowing what is under the skin and so because our algorithm is primarily volumetric/anthropometric based and assumes natural bodies, implants will affect the body composition numbers in an unnatural way.

"The Fit3D Body Composition results are different than what I'm used to..."

Body composition is almost like religion. The only real way to ascertain accuracy is through cadaver studies and therefore people generally use what they know. Please see this post from Body Spec (A mobile DXA company) to further explain:

The Big Fat Experiment

As with most forms of body composition testing, extremely lean athletes are underrepresented in studies as is the case with us. While we do a "good" job of assessing body fat for the very lean population, our current algorithm will over represent them on average. This is further exacerbated because many lean people have a misunderstanding of how much body fat they actually have. If a leaner person, used to more readily available devices, were to take a DXA test, I would assume that they would be between Fit3D and Bod Pod in body fat. Furthermore, future releases of our body composition algorithms will continue to perform better as we aggregate additional control data.

We looked closely into different options and have done studies, but find that equations like Siri and Brozek are over simplified and are not actually good determinations of body fat across populations. This is why we correlated directly with DXA vs. bod pod or bio-impedance. The other challenge that we face is that hair is "volume" in our system, so unless people are wearing swim caps, the volume of the head is quite a bit larger than in real life. Again, because volume based equations are so simple, any slight variation will cause undesired inaccuracies.

Our system uses fairly common infrared depth mapping cameras to get the information used to create our avatars. The sensor is very similar to the Microsoft Kinect that is used in 10s of millions of households worldwide to play video games or to the technology used in the iPhoneX for face scanning.

The laser in our systems is controlled by software. Running apps that turn on depth streaming will activate the laser and operate it at a safe level.

Conditions including pregnancy, implants, pacemakers, etc. should neither be affected by the scan nor affect the scan results. If you have any specific concerns, please consult with your physician.

If you have any further concerns or questions about this subject, please reach out to our support team and we're happy to respond!