Find out your bodyfat percentage, get great fitness and nutrition programs (soon), have a robot tell you how sexy you look, see yourself in 3D and compare yourself to Justin Bieber.
Yes, Bodywhat will be free to use as long as it's in beta, and we intend to remain free for as long as possible after launch. Our other services (fitness and nutrition coach) will be subscription-based.
The Muscle Index reflects how 'muscular' one looks: the more muscle the person has and the lower his bodyfat is, the higher his Muscle Index gets. It scales linearly with a person's Lean Mass, decreases as his bodyfat increases, and is height-independant.
In concrete terms, it is calculated as follows:
Where the FatPenaltyFactor is a value that decreases as the bodyfat increases (e.g. if two persons have the same height and the same lean mass, the person with the lower bodyfat will have the higher Muscle Index). This formula is very similar to the Fat-Free Mass Index (FFMI) except that, here, you get a penalty for high bodyfat values.
The value is then scaled to be out of ten. The average person has a Muscle Index of about three, whereas bodybuilders can have a Muscle Index exceeding twelve (!).
This rating is initially determined by what is called a "nearest-neighbors" interpolation: Bodywhat will determine how 'sexy' you look by comparing your body to thousands of others, and then regressing your own sexy rating as a weighted-average of those who look the most like you.
If you're wondering how Bodywhat knows which bodies "look like" yours: Bodywhat does so by using the same computer vision techniques as those that are used in facial recognition, but instead of applying those to faces, Bodywhat applies them to body pictures. If you're interested in learning more about these, Wikipedia's article about Eigenfaces is a great starting point.
In layman's terms, your Sexy Index rating is an average of the sexy ratings of other people who look like you.
Once your initial rating is set, other users will be able to alter it by up-voting or down-voting it from your report's page (if your report is set to 'public', that is).
/!\ Please do not take this rating too seriously. It doesn't take into account your face, your entire body, and your charm as a person.
Your bodyfat percentage is computed in a fashion similar to the good-looks rating: once your body picture is processed and normalized, Bodywhat's algorithms will determine your bodyfat percentage by comparing it to thousands of others kept in a separate learning set.
The way those comparisons are performed, however, is more intricate. Bodywhat uses a combination of Computer Vision and Machine Learning methods in order to infer as much information as possible from the data that is being supplied (including your body picture, but also your height, weight, age and gender).
How precise are those body fat estimates? This is a difficult question to answer, since getting a verified evaluation set for testing purposes is a tricky task in the first place. As of today, MRI imaging is the only method considered to deliver near-perfect body composition estimates in a consistent manner. Without putting an exact figure on it, we believe our 95% confidence interval lays somewhere between ±3.0% and ±3.5%.
One must keep in mind that the precision of our estimates is bound to increase over time, as our learning set gets larger and our algorithms become more refined.
Bodywhat's algorithms make mistakes sometimes. That may happen especially with atypical physiques, or with pictures of poor quality (because no good matches were found in the database).
If you think this is the case for you, click on the message 'I think this bodyfat value is wrong...' that pops up when you hover over your bodyfat percentage. Your report will be then queued for reprocessing.
Reprocessing will re-estimate the bodyfat value of your report using a different estimation sample. What happens is that, while staying under certain constraints, Bodywhat will try to gradually alter its regression method until a significant difference with the previous estimate arises. Sometimes, Bodywhat might fail at that task; the newly estimated value may remain very close to the old one.
Queued reports may be reprocessed at any time, when server resources allow it. You will be notified by email once your report reprocessing is done.
Your Fat-Free Mass Index (FFMI) is like your Body Mass Index (BMI), except that we don't take into account the weight of your fat, only the weight of your lean mass. It is a reliable index of muscle development, and it doesn't depend on your height. It is calculated as follows:
The higher it is, the more muscular you are. For instance, regular people may have an FFMI anywhere between 17 and 22, whereas bodybuilders can have a FFMI exceeding 30 (!).
Your Daily Calorie Needs, also called Total Daily Energy Expenditure (TDEE), is how much you need to eat every day to sustain your current weight, assuming you're doing a light amount of exercise (like, say, going to the gym once a week). This is calculated based on an approximation of your Basal Metabolic Rate (BMR), which itself depends on your gender, age, height, weight, and body fat percentage.
Computer vision, point clouds, morphable models and wizardry.