Viewing 37 posts - 1 through 37 (of 37 total)
  • Bathroom Scale irritation
  • Premier Icon WorldClassAccident
    Free Member

    I have been told to lose weight and to use the bathroom scales to measure the weekly trend. Easy right?

    We have some super accurate digital scale with multiple sensors to get the true and accurate reading (it says in the advert).

    I place the scales on a hard tiled surface and stand on them. My total body weight is now on the scales and does not change. Assuming their are 4 sensors in the scale it should surely add up the weight thought each sensor, do some maths and show the total weight.

    This total weight does not change if I lean forward to read the display, raise my arm to scratch my head, step off for a few seconds and then step back on so why does the scale vary + or – up to 4KG?

    I accept I don’t need to the nearest gram, I want a trend but I would expect it to stay within 1KG during repeated identical checks.

    Premier Icon lucky7500
    Full Member

    No help but I have some Salter ‘Ultimate Accuracy’ bathroom scales with the same issue. I can step on & off them with the readout remaining the same but if the scale turns off then I step back on there is often a drop in the weight shown! I have no idea which the ‘correct’ one is!

    Premier Icon wobbliscott
    Full Member

    This total weight does not change if I lean forward to read the display, raise my arm to scratch my head, step off for a few seconds and then step back on so why does the scale vary + or – up to 4KG?

    Your mass doesn’t change but the force you apply to the scales does – and that is what the scales are measuring. A combination of Newtons first and third laws creates accelerations in different directions which can either add or subtract to the total force you apply to the scales. As you lift your arm you are creating a force because you are accelerating a mass – that mass reacts in an equal and opposite direction that is shown on the scales display. The amount of ‘deflection’ you see in the scales reading is just a measure of the sensitivity of the sensors. Measuring dynamic forces is harder than measuring static ones so you might get spurious readings while you’re flailing your arms about or leaning forward and backwards. You should stand on the scales and be as still and balanced as possible while it takes the reading.

    I haven’t got fancy pants scales at home and of the 4 feet three is only a load sensor in one of the feet so it doesn’t have the ability to do fancy dynamic calculations while you move around on the platter. A case of step on them and stand as still as possible until the reading has been taken.

    Premier Icon Kryton57
    Full Member

    Yeah they are shit, mine are constantly reporting me over weight.

    Premier Icon johnners
    Free Member

    My scales won’t work if I’m moving, I need to stay still for several seconds to get a reading so they seem to be smart enough to filter out the dynamic forces wobbliscott’s describing. They can still vary by a kilo or so if I take 2 readings in close succession though.

    I don’t really care, I weigh myself every morning and it’s the general trend I’m after.

    Premier Icon Greybeard
    Full Member

    Measuring dynamic forces is harder than measuring static ones so you might get spurious readings while you’re flailing your arms about or leaning forward and backwards.

    But he’s not getting spurious readings when he moves his arms, the reading doesn’t change. So there’s something in the software (/firmware) of the scales which is ‘stabilising’ the reading. My guess is that is what is resulting in the difference between readings on each attempt – as you get on the scales, they try to smooth out the dynamic effects – which inevitably means picking a value from a varying input and presenting that. All electronic scales seem to do this, so perhaps they all use the same 20 year old chip design.

    Premier Icon hooli
    Free Member

    I think they all do it. I tend to just put the scales on the same spot of floor each time and take the first reading. The readings are always up and down by a few lbs (could be the scales or could be me being dehydrated?) but the overall trend shows if I’m losing or gaining.

    Premier Icon MoreCashThanDash
    Full Member

    Yeah they are shit, mine are constantly reporting me over weight.

    I thought it was just me….

    Premier Icon redmex
    Free Member

    Chuck away the scales and buy a pair of jeans two sizes too big , put them on and like bobs your uncle your waist looks great and you can then eat your steakybake and fudge donut guilt free
    Repeat as many times needed

    Premier Icon tjagain
    Full Member

    Mine if step on and off them it gives a lower reading the second time.

    Premier Icon igm
    Full Member

    Mine if step on and off them it gives a lower reading the second time.

    It’s down to the calories you have burnt in those 2 seconds TJ. Both readings are correct.

    Honest.

    Premier Icon slowoldman
    Full Member

    Well all I can say is these smart scales sound shite. Our old fashioned spring jobs are spot on to the pound.

    Premier Icon tjagain
    Full Member

    4 kilos igm?

    Premier Icon ransos
    Free Member

    step off for a few seconds and then step back on so why does the scale vary + or – up to 4KG?

    Mine do exactly the same. I’m tempted to go back to an analogue set.

    Premier Icon Bazz
    Free Member

    Everyone knows that the lowest reading is the correct weight 😁

    Premier Icon igm
    Full Member

    4 kilos igm?

    Absolutely 😜

    Premier Icon Keva
    Free Member

    the cheap ones I bought from Wilko for a tenner only vary by a couple of KGs at the most, which I assume is hydration. So if it shows me a couple of KGs down I know it’s time to go to the pub for a couple of pints.

    Premier Icon crumpsbutts
    Free Member

    Repeat readings on mine are always within 0.1kg to the point that I almost wonder if it’s fudging the numbers for consistency’s sake. I’d hope not though becuase they were more than I wanted to spend on a pair of scales (Withings).

    Premier Icon WorldClassAccident
    Free Member

    Just to clarify, I was not being weighed while I moved my arm. It just seems to vary the weight it reads based as much on body position as anything else. Ther mass is the same regardless of (stationary) body position. The scales seem unable to measure this.

    I looked at getting some medically accurate ones but they start at £135 so decided to whinge on here instead.

    Premier Icon Murray
    Full Member

    Just tried my Salter Digital Glass Scales. Weight is the same each time I get on. Doesn’t vary if I lean or put my arms out. Refuses to read if I stand on one leg i.e. most weight on one side.

    They were about £20 10 years ago – model’s no longer available but they sell similar ones still.

    Premier Icon dangeourbrain
    Full Member

    Are your feet in the same place every time? Might sound daft but where you are in relation to the sensors can make quite a difference to the reading despite the fact your mass obviously doesn’t change.

    Premier Icon Murray
    Full Member

    That’s why I tried standing on one foot – looks like the scales error out if they don’t get a consistent reading. The scales are about 1 foot square so not a lot of room to move around!

    Premier Icon leffeboy
    Full Member

    Repeat readings on mine are always within 0.1kg to the point that I almost wonder if it’s fudging the numbers for consistency’s sake.

    I think the answer is yes.  I experimented withine by holding a 1kg weight when I stepped on a second time and I still got the same reading.  I had to fake a very different reading by half stepping on it before it would weigh correctly again

    Premier Icon IdleJon
    Full Member

    Your mass doesn’t change but the force you apply to the scales does – and that is what the scales are measuring. A combination of Newtons first and third laws sciencey blah, blah babble

    The scales have one single job to do – to measure his weight. if they show a difference in weight because he is scratching his balls then it’s not doing the job at all. The scales should be able to convert the scientific waffle into an actual, simple weight, especially if they are expensive ones.

    It’s just like my sat-nav asking me if I want to take the shorter route. I don’t know WTF I’m going! Why would you even suggest a longer route, you jumped up toaster!

    Premier Icon WorldClassAccident
    Free Member

    I have taken phots to prove the fault with the scale and its inability to correctly measure a static mass.

    Look at the heel position compared to the logo at the back of the scale and see how little position change effects the weight. This was while attempting to actually get a consistent weight. I am sure I could have exaggerated the effect quite easily.


    Ultimate Accuracy huh?

    And obviously they are overweighing by about 10KG 🙂

    Premier Icon jonzi
    Full Member

    I have the nokia scales, when I put them on the floor and stand straight on them, they read just under 2kg heavier than they should

    I think that it kinda resets its self after being laid down

    So now, I lay them down, stick a foot on to wake it up, then wait for it to turn off (only a few seconds) and then stand on them again

    Pricy scales, bit annoying I have to do that.

    Premier Icon WorldClassAccident
    Free Member

    Jonzi – these are the same and the readings you see is after having done that

    Premier Icon MrPottatoHead
    Free Member

    Are scales calibrated to be more accurate within a certain range? I get similar effects as above on my digital scales whereas my wife and son who are significantly lighter don’t get anywhere near the same variations.

    Premier Icon bigblackshed
    Full Member

    We’ve got some glass Salter ones. Reading the instructions, yes, I read them!!!!, you have to put them on the floor, gently step on them with enough force to turn them on, step off and wait until they turn off, a few seconds. Then step on them to weigh yourself. When you step off allow them to urn themselves off again, then step on to weigh yourself.

    Mine will give a big discrepancy if I don’t do the power on / off cycle first.

    Premier Icon Northwind
    Full Member

    I get the impression that modern scales are all built to produce a reading really quickly- people want instant answers, they don’t want to wait, so rather than taking time to settle like an analogue scale would, you get more of an approximate

    Premier Icon Northwind
    Full Member

    Also, it made me think about how …And You Will Know Them By The Trail Of Dead have mellowed over time, no more Richter Scale Madness, now it’s just Bathroom Scale Irritation

    Premier Icon Wibble89
    Free Member

    How many load cells does it have? One for each foot under the scales (four) or just under either the front or back feet (two)?

    Seen some with only two sensors so if you stand in different places the basic algorithm assumes total weight is the average of the two monitored times two (half the weight/force being taken by the “dumb” feet).

    Could that be part of the issue?

    Premier Icon poly
    Free Member

    WCA – not sure if you’ve got massive feet or a particularly small set of scales, but in either case if you look at where your weight distribution is it is all at the back – when I use mine (I gave up – they keep telling me things I don’t like) I try to have same gap from tow to front edge as heel to back edge. If MrPotatoHead is right and his are more consistent for wife and kids it may be they have smaller feet and are naturally more central.

    Premier Icon dangeourbrain
    Full Member

    Also those scales aren’t in the same place so that won’t help

    Premier Icon jamiemcf
    Full Member

    Doesn’t help but if you go to East links farm in East Lothian they have some scales that tell you how heavy you are compared to farm yard animals, singular and multiple.

    In all seriousness I’ve had similar with mine.
    Always make sure you measure at the same time. I did it first thing straight after a pee in the morning. I was at my lightest I figured but a more repeatable figure.

    Premier Icon MrPottatoHead
    Free Member

    They have some scales that tell you how heavy you are compared to farm yard animals

    I was at a rodeo in Canada once and they were kind enough to let people use the cattle scales to print off their weight/cost in meat.

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