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Ask WHOOP: Why Do We Collect Demographic Data At Sign Up?

June 19, 2019

When you create your WHOOP membership, we collect some personal data such as your height, weight, sex, and fitness level. Many of you have reached out asking what we do with this information, and because we recognize that disclosing personal information is potentially uncomfortable, we wanted to take a moment to clarify when and where we use it.


Calorie Burn Estimations

Our calorie burn estimates build on decades of research which has shown that short of measuring gas exchange directly, caloric burn formulas including sex, height, and weight are more accurate than those that don’t control for those things, and therefore are essential in delivering the most accurate estimates of caloric consumption possible with a wrist-worn device.

Even after controlling for height and weight, we see differences in caloric consumption at rest (basal metabolic rate) and during activities explained by biological sex. This phenomenon seems to be primarily driven by differences in muscle mass (those with greater muscle mass burn more calories than do those with less muscle mass) and differences in testosterone levels (testosterone increases basal metabolic rate).

While we know that muscle mass and testosterone levels vary meaningfully across individuals and that binary sex is an imperfect predictor of these two factors, for most individuals most of the time, including this information results in a more accurate prediction of caloric consumption than would be possible without it.

In order to get the most out of your WHOOP membership, we recommend that you periodically update your weight in order to keep these estimates as accurate as possible. You can update your sex, height, and weight by hitting the pencil icon in the upper right corner of the profile page on your mobile application.



The WHOOP “secret sauce” comes from our ability to learn from all the data we collect from you and use it to personalize our algorithms. This enables every score to reflect what it means for you to produce the metrics you just produced.

For example, everyone needs a different amount of sleep each night to be fully restored, so 7.5 hours might be great for one person and insufficient for another. A completely personalized analytics experience has one downside–the need to calibrate. When you create your WHOOP account, our first task is to get to know you as quickly as possible. Rather than have every member calibrate from the same starting point, we use the demographic information you provide at signup to create the best possible “starting point” for your calibration. The better you fit our guess about what your data will look like the faster you calibrate, and using your reported sex and fitness level data allows us to predict better calibration baselines than we could without that information.

If you don’t fit the mould, well, no worries, we’ll still figure it out in a week or so. And, once you are fully calibrated, we actually no longer use fitness level in our algorithms.


Weekly Performance Assessment Comparisons

On the final page of the Weekly Performance Assessment, we compare each member’s data to other WHOOP members of the same age range and gender. We do this in order to provide the most relevant context to your data, and because many of our members requested this comparison and enjoy seeing it. However, comparison to peers is never incorporated into any of the scores or algorithms.



Behind the scenes, we also use your demographic data for internal research. It helps our analysts know which populations we are serving well and where we need to focus future development. We also use demographic information to understand patterns in the data, like what we did for World Sleep Day last March.


What We Don’t Use It For

Also worth mentioning, we never sell your data, demographic or otherwise, to third parties.


“Ask WHOOP” is a new concept we’re trying out on The Locker. From time to time we’ll answer questions from our members regarding the various features and analysis WHOOP provides, how to better understand the data, and general tips and tricks for optimizing performance and making the most of your experience on WHOOP.

Have a question you’d like to submit for us to answer in an upcoming post? Email with “Ask WHOOP” in the subject line.


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Emily Capodilupo

Emily Capodilupo is VP of Data Science and Research at WHOOP. Before joining WHOOP in 2013 as the first full-time employee and first scientist, Emily studied Neurobiology at Harvard University and studied circadian biology in the Analytical and Modeling Unit of the Division of Sleep Medicine at Harvard's Brigham and Women's Hospital. As a runner and former gymnast, Emily knows first hand the importance of sleep and recovery for peak performance.