Weight Weight, Don’t Tell Me

I love weighted moving averages. They provide an elegant representation of a regular measurement, while smoothing out the day-to-day changes. It’s an ideal way to track your weight, where the daily change can seem significant, but the long-term trend is what really matters.

The problem is, to track something over a period of time, you need to measure and record it religiously. For weight, this means hopping on the scales daily, and remembering to go and enter the numbers into your recording device each time. There are websites that will help with the tracking – I love fatsecret.com and livestrong.com – but they don’t magically suck the data out of your scales.

What we need here are some scales with, I dunno, WiFi or something. “Hrmm,” he says, scratching his enormous belly, “if only there was such a thing available.”

Withings ScalesHark! The WiFi Scales from Withings.com. Once you’ve set these up with a bit of your standard jiggery-pokery, you simply stand on them once a day, and everything else is taken care of. A few minutes after weighing yourself, you’ll find a new entry recorded at the Withings.com website, complete with a sexy graph. The data can be made public if you choose, and you can even use their iPhone app to show your friends how heavy you are.

Withings Graph
Ed's note: this is not my weight

The scales also measure your body fat percentage – albeit using a somewhat inaccurate method. The important thing is that the measurement is consistent, which does give you a useful long-term trend.

The Withings Scales are incredibly easy to use. My current digital scales require me to tap them, then wait for a zero measurement, and only then can I weigh myself. With the Withings, I can jump straight on the scales and get an immediately depressing measurement. Brilliant!

The only things missing from Withings are an API for data access, and – ironically – a weighted moving average on their default graph. You can export your data in CSV, but I’d like to see an API so I can pump data into a more complete third-party health site like fatsecret.com.

What are you weighting for?

Currently the only way to get these scales in New Zealand is via the Australian reseller. They do support a 1 year warranty, but will add a shipping charge onto your purchase, which means the scales will cost you AU$295, or about $370 kiwi. Fairly steep, but what price convenience?


  1. Hi Ben,
    my ears perked to your piece on scales on the breakfast show!

    Such scales are already here in NZ, not sourced from Australia, but from myself the authorised distributor of TANITA the INVENTOR of this category of product.


    Anything else is just a copy-cat imitation of Tanita, and as you say unlikely to be accurate, and I add, unlikely to be of satisfactory quality.

    A NZ University just bought 7 of our top-of-the-line model for a longitudinal research study on elderly, such is their confidence in the reliability and accuracy of our product!

    Unlike the product you demonstrated, along with wireless to PC, ours comes with a desktop or bathroom vanity display unit !

    But anyway, thankyou for alerting me to competition!

    Kerry James Goodhew
    [Ed: Spammy signature removed. One link is plenty]

    1. Dear god, what’s up with your website?

      It’s horrible, the color scheme is tacky, the layout if confusing, and when viewed in firefox all of the images are broken.

      The majority of potential customers that visit your site will be driven away, concerned that the quality of your site represents the quality of your product.

      The rest will likely be driven away, worried that it’s not even a legitimate website.

      I highly recommend you do something about it.

  2. @Kerry
    I was referring to the inaccuracy of impedance analysis in general. Unless you know something I don’t, Tanita are just as inaccurate as any other scales that use this method to measure body fat.

    See this Wikipedia article:
    “As electricity travels more easily through water, a person who has consumed a large amount of water before the test will measure as a lower body fat percentage. Less water will increase the percentage of body fat. Also reducing the reliability of this method is the variation between models of the BIA devices: for instance when comparing outputs from a Tanita scale to an Omron Body Logic handheld device the Tanita scale overestimated the percentage body fat in college-aged men by 40% and in college aged women by 55%”

  3. HiBen!
    yes, I saw your reference. I am an exercise physiologist (sport scientist) myself and have studied anthropometric methods of measurement for years. That single reference is just that a single reference with quite a ridiculous result that actually questioned the competence of the experimenter(s). Just read that paragraph alone. It compares a hand-held device that can only measure the upper body (inaccurate method per se!) to Tanita. Then states denigrating results of Tanita without mentioning the hand-held device results! What? Was the hand-held device put up as the gold standard? Come on? That is just such an appalling ridiculous statement. I deleted it from Wiki. I really would like to know who the anonymous author is.

    As you might expect I have a host of supportive literature on TANITA.

    FYI, foot-plate only scales have an R value of about 92%, which is totally fine accuracy in a home product priced from approx $100 …don’t you think? Our top of the line Segmental consumer models have R value around 95% against DXA. It does this by 8 electrodes: 4 foot, and 4 hand. Hence, our Segmental selected for research since it has exactly the same technical spec’s, giving exactly the same measures, as Tanita’s commercial products found in research centers of Universites and hospitals, DHB’s etc! Even DXA itself, the gold standard, is theorised as max accuracy to about 97% ! DXA also relies on regressional statistical analysis! BTW, In the early days of development of the DXA method it was this US$100,000 machine that had errors of 50%!!! The only way to get a 100% accurate measure is to take a body and boil it down, skimming off the fat!

    On body-water and hydration, this is held up by those lacking logic as a point of inacuracy or un-reliability. This is a nonsense of their own arguement. ALL SCIENTIFIC MEASURES REQUIRE A STANDARDISATION OF MEASURING PROCEDURE. For example, if you ran to your Dr and she slapped a BP monitor on you to show that you had screamingly high blood pressure does she rush you to intensive care? No! she probably asks, “did you run here?”, and then asks you to lie still for another 10 minutes. Do you throw out the BP monitor because of this strange out of place high result one minute and 10 minutes later you had low BP? No! We act sensibly.

    Again: If you stand on a set of ordinary weight-only scales to show 100kg, walk out of the room to drink a large glass of water, happen to stand on them again to see 100.50 kg do you really cry out inaccurate, unreliable, and slander the brand/maker? A person’s weight actually changes almost hourly through the day and therefore so does the PROPORTION thst is water, that is fat, that is muscle etc. The machine is not inaccurate or unreliable, by nature being a biological organism it is the human body itself that is unreliable and inaccaurate by changing moment to moment!

    The TANITA scale provides a measure of your current hydation = BW%. This is actually a reliability check. It also helps a lot of people, particularly athletes to maintain optimum hydration. Shorty Clark of Whanganui, a world class triathlete travels with his Tanita to get his hydration right after international flights! The instructions to ensure realiability are clear and simple: Standardise your measuring by doing it at the same time of day, when fully hydrated but not immediately after drinking or eating, not after extreme physical work etc. Can people cope with these simple requirements? I think so. ….but seems many ‘so called’ scientific writers cannot cope with a simple requirement of the ‘scientific method’ being to standardise procedure when testing!

    If you wonder and are surprised at my broad-side at scientists just contemplate the revelation on the logic and intelligence of scientists over the climate and carbon tax debate! …that has got to shake the too long “scientist on a pedestal worshipping” by the world’s non-scientists who nevertheles have ‘common sense’!

    Your turn 😉

  4. Wonderful detail thanks!

    I think that’s the point I made on Breakfast this morning? They’re not terribly accurate, but they are consistent? I presume the Withings scale is on-par with footpad only Tanita scales.

    Out of interest, what $$ are we looking at for a set of Tanita scales that match the Withings? Footpad BMI, no tapping or fiddling to turn them on, WiFi upload, and a nice online graphing interface?

    I’d be totally happy to test a set for you.

  5. Cheers!
    price-point interestingly is same! …but tha add-on (not imperative!) of the bench-top unit takes it higher.

    As your first correspondent stated price is up there and can he/she justify it, but it is a product to tap people who want the best of anything and can afford it without question. Same thing as a POLAR HR monitor …there is the GPS version that prints out all the HR data along with mountain scape profiles etc costing $800! But then there is the entry level basic HR readout model for $120 !
    Myself, a bit of a geek with this stuff too, …but I mostly go out and hit the hills with my hundred buck HR monitor! 😉

    will get back to you with demo unit to suss out when one is free.

  6. I prefer WIFI to bluetooth for the scales. Its a lot more flexible. I havent tried Tanita but from what I have read they only have Bluetooth. The other important factor is that Withings have an iPhone application. Not sure if Tanita have them? So all these are factors too.

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