Is the body composition feature just a BMI calculator?

dlperussi Registered Users Posts: 2
New Seeker
edited January 24 in TomTom Sports
I decided to buy the Tomtom Touch Fitness Tracker due to the body composition measurement feature. I did some research online and although most people said it wasn't accurate, they claimed the results were consistent, that is, if you took into account the trends instead of the values themselves (exactly what I was looking for).
After initial tests, I could see where they were coming from since the readings really weren't at all accurate but I was still hoping for consistency. I did realize, though, that taking multiple readings throughout the day didn't show different body percentages (even the best scales in the market will show variations during the day) which seemed very odd. I decided to try the tracker on other people's arms and STILL the readings didn't change. Then I reset my account data, took a reading on my own wrist again and the result turned out different than before. Also, I realized that if I set a different weight/height in my profile the readings will always vary and toward the BMI. I started testing out and basically the values shown in the body fat percentages just follow the basic height and weight BMI calculation. Does anybody know why the readings won't vary throughout the day (although they vary broadly if I reset my data and "start from scratch") or if this is really just a calculator posing as a bioimpedance tracker?


  • tfarabaugh
    tfarabaugh Posts: 17,004
    Why did you buy a device that was discontinued from a company that went out of business over 2 years ago? I would strongly suggest returning it as there is no more development, no replacement straps and very limited support available.

    That being said, the readings should not vary during the day, it is not like you convert muscle to fat over the day. The numbers are meant to be looked at the long term over weeks and months, not over a single day. And you can't have someone else use it as the stats will be wrong. The important thing to look at is not the actual number itself, but at the trend. Is the number going up and down over time (looking at weeks and months, not days)? That is the key, to look at the trend, not at a specific number. The measurement is also heavily influenced by the time of day you take it, your hydration level, where you are on your menses cycle (for women) and other factors that it will vary day by day. By looking at it over the long term and seeing how it is trending you will get value out of it.
  • dlperussi
    dlperussi Registered Users Posts: 2
    New Seeker
    edited November 2019
    You contradict yourself. First you say the readings should not vary since you don't convert muscle to fat during the day (you are wrong on that, though, since readings do vary a lot during the day, which is why it is recommended you take readings at the same time every time). Then you got it right near the end, which is exactly the issue I am asking: why won't the percentages vary considering any serious device would point out those variations.

    If the trends will just vary according to the occasional weight updates then the tracker is in fact just a BMI calculator.

    Answering the other part, I bought it because I want to own a body composition tracker other than the scale I currently own. It's that simple. Tomtom seemed to be worth a try even though it was discontinued considering reviews claimed it was inaccurate but consistent. I asked a question here to see if anybody had any helpful insight on it.