Withings scale issue?

Hi all

I’ve been using a Withings scale for the last 4 months. Body fat percentage started at 30% and dropped to 25% over the course of those 4 months. Muscle mass never went above 67% which, according to the scale, is well under the average.

Last week I found out from another TR user that the scale has an athlete mode, it should be used for anyone who exercises 8+ hours a week and has a resting heart rate under 60bpm.

I turned on heart rate mode and my fat percentage dropped to 18% and muscle mass went up to 80%, this has been the consistent reading for the last week. Have I been using the scale wrong this whole time or is the scale borked?

I have the same scale and do not use athlete mode. My body fat percentage started at 26% and currently at 22%. I’m now curious as to what changing the mode over to to athlete mode would read for me… Hmmm

What is the recommended mode? I am sort of all over the board on hours per week, anywhere from 6.5-12 hours a week. It’s never the same, some weekends I do longer rides than other. I’d like to think I’m an athlete, but I don’t race with anyone but myself. Always chasing that speed gain or PR improvement.


I have no idea if the following applies to this scale, but the TR crew found that the Tanita settings showed:

  • Scale @ Regular = Approximate correlation with DEXA scans of Total Body Fat (subcutaneous, visceral, etc.)

  • Scale @ Athlete = Approximate correlation with skin caliper body fat measurement (subcutaneous only)

If the above is true, it seems likely best to use the Regular setting to track your entire fat percentage and it’s relation to muscle mass and everything else.

See Nate’s original thread for a deeper dive and related discussion:


Thanks for pulling out that info Chad, I knew it was too good to be true.

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Didn’t @Nate_Pearson have a spreadsheet with the body cardio scale (which I believe is a withings sub-brand)?

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I have the same withings scale and have recently done a Dexa scan recently so I might be able to give a bit of an idea on how accurate it is.

For me it hovers around 9-10% body fat in normal mode, however if I put it in athlete mode it shows 3%…

My Dexa scan shows 14.5% body fat.

The athlete mode is pretty much lying to you, I would keep it on the normal mode and assume even that reads a bit low.

You seem to be making good and steady progress though so keep it up!


That was a good podcast!

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Yeah after I clicked on that link by @mcneese.chad and saw what 17% body fat looked like, I immediately thought about setting the scale on fire for lying to me so blatantly.


Yeah, they are less that accurate… I find that as long as I am weighing myself at the same time each day I can trust the trends from week to week but not so much the actual numbers.


Body+ - Using the Athlete mode

Why is there an Athlete mode?

For users with a certain body type, our regular algorithm may provide an inaccurate Fat Mass measurement. When Athlete mode is enabled, an alternate algorithm is used to calculate Fat Mass for that user’s measurements.

How can I tell if I should use Athlete mode?

If you work out more than 8 hours a week and have a resting heart rate below 60 bpm, you may need to use the Athlete mode.

What effect will enabling Athlete mode have on my Body Composition measurements?

When Athlete mode is enabled, Fat Mass measurement values will be lower and muscle mass measurement values will be higher because the user’s athletic body type is taken into account.

To activate the Athlete mode, perform the following steps:

  1. Open the Health Mate® app.

  2. Go to Profile .

  3. Tap your name under your profile picture.

That’s what there site says for it… I have it enabled… not sure why they have this…

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I don’t think it matters what mode you’re in, as long as you’re consistent. Then just make sure it goes down :smiley:.


Non-athlete/regular mode tracks pretty closely with my Dexa scans, fwiw


Agreed, unfortunately mine is going to show a massive jump in BF% when I go back to normal mode :stuck_out_tongue:


I have it on athletic mode cause it makes me feel good


The scale is starting to annoy me. I weigh myself daily about the same time. Making some progress as far as I know from looking in the mirror and the way my clothes is fitting. From the scale as well as far as weight goes.

So here is the annoying thing. My body fat mass on the scale varies by as much as 6%. Going up to 28% which is a total disappointment, and then swings down to 22% the next day. I am consistent on my eating habits, eat basically the same thing every day.

An observation I have made is when very well hydrated the scale reads at a lower fat mass percentage. My muscle mass also shows an increase when more hydrated as well. I’m not sure why it does that, but it’s something I have noticed.

I work a very physical job UPS, My water intake does vary quite a bit on a daily basis. Some days I need to consume more water just cause of weather conditions, hotter weather obviously I drink more water.

Does anyone else have similar issues or annoyances with the scale, in especially big swings in fat mass from day to day?

Large swings in hydration and glycogen stores will make a large difference in the muscle mass readings on your scale, especially an impedance based one. Muscle tissue carries more water than fat tissue.

Don’t sweat the variation, just look at the long term trend along with the other indicators you’ve mentioned.

Since you have a physical job, you are going to get more swings than other people.


Best thing to do is wake up, use the toilet, then weight (nude). That’s about as consistent a measurement that you’re going to get. From there, what you’ll want to do is ignore the day-to-day variations and instead track a 3- or 5-day moving average.

If I weigh after a workout, it’s to make sure I’ve approximately replaced fluids by the weight. A wide swing the bf% will tell you whether the water has been absorbed yet, or is just sitting in your gut still.


I’ve owned this scale for 1.5 months and registered 10 readings across 5 “parameters” captured by the unit. They include;

Weight (lb)
Fat mass (lb)
Bone mass (lb)
Muscle mass (lb)
Hydration (lb)

One might predict that some of these parameters are correlated over time. For example, any one or all of the mass readings might correlate to overall weight as trends over time. Regardless, I would accepts correlated trends, but not exact trends. To examine this I calculated z-scores for each parameter across the ten readings and plotted them. I then calculated the regressions for each and the numbers indicate that the data is far too tightly connected. For example, the equations for the regression comparing the “weight” readings and the " fat mass" readings are as follows;

y = 0.0516x - 2299.6 (weight)
y = 0.0517x - 2302.7 (fat mass)

Similarly, the equations comparing “bone mass,” “muscle mass,” and “hydration” are as follows;

y = -0.005x + 221.77 (bone mass)
y = -0.004x + 176.72 (muscle mass)
y = -0.004x + 194.2 (hydration)

There is essentially zero chance that these are truly independent measurements (based on slope alone) with any connection to distinct biological phenomenon. Other than weight, frankly I don’t know what this device is measuring. Even in a relative sense, it’s impossible to know what day-to-day differences mean.

I’vee just changed my account over to “athlete mode” and will repeat this analysis in another 1-2 months assuming more than 10 readings.

I have that scale for a few years but didn’t know about ahtlete mode. I’m using it regulary every morning and my BFs are always between 12 and 13.5% and yesterday I switched to athlete mode and got 4.6% today…

I am 33 and my weight is pretty consistent in about 69kg and I’m 180cm but I look much lighter then I am…
Training about 10+hrs and RHR is 45-50.

12% looks too much but less than a 5% is maybe too low.

I just measured with cheep plastic caliper my belly fat and get something between 4-5mm

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I think mine is broken too. The numbers seem to get bigger…

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