Water Weight and Body Fat

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SouthWestLondon
SouthWestLondon Posts: 134 Member
in Health and Weight Loss
Hi folks - I have a question about the body fat and water weight percentages on my scale. They vary wildly from time to time. From 39% Fat/43% Water to 26% Fat/56% Water. Fat and water together always make up about 82% with muscle, bone making up the other 18% with a fairly consistent split between them.

I know that fluctuations are normal, so I've stopped paying too much attention to the fat and water percentages. But I still try and draw some lessons for what the figures mean for my weight loss.

Am I right in this interpretation? If my fat is low (say 26%) and water is high (56%), does this indicate that my body is holding on to more water right now for some reason (salt intake, response to exercise etc). And then when fat is high and water low, is it the opposite?

In practical terms I don't think any of this matters in terms of my plan - my current approach to calorie deficit of keeping below 1750 average per day is working. But I'd like to have a better idea of what the fat and water numbers mean*


*secretly I'm hoping that these figures mean I'm carrying a little more water weight than usual for some reason, and that therefore maybe my fat loss has been better than the scales are showing - is this just total wishful thinking?*

Replies

  • Cherimoose
    Cherimoose Posts: 5,208 Member
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    Yes, if you're carrying more water due to extra carbs, sodium, etc, then the scale will think you have less fat. But those scales aren't very accurate to begin for estimating body composition, so that may explain some of the variance. I use them more for entertainment value. :+1:
  • SouthWestLondon
    SouthWestLondon Posts: 134 Member
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    Thanks guys - have had really good loss the last couple of days (like 5.6lbs in five days!). I assume that is mainly water coming back off after I had an indulgent (and very high sodium) weekend. But my scales still show me at 56% water, which is really high for me.

    So I'm not sure whether that means I am still carrying more water than usual and might lose a few more lbs in water weight before settling down.
  • heybales
    heybales Posts: 18,842 Member
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    It means you are attempting to read too much into a scale that relies on statistical averages and has an accuracy rate of probably 10-20% on the body fat figure, and worse on the others.

    Days of time even on just weight really isn't useful, especially with the figures you are talking about.
  • FitAgainBy55
    FitAgainBy55 Posts: 179 Member
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    I have both an Aria scale and a hand held impedance device. I've also had my body fat measured using hydrostatic weighing. For the most part I don't think the impedance devices are accurate, so I ignore those measurements.

    Here's a simpler approach -- if your weight changes by a pound or more (either direction) day to day -- it's water weight. You didn't add or lose (unless you are several hundred pounds) 1 lb of fat or muscle in one day.

    Just judge progress by overall trend on an average basis over 1 or 2 weeks not on a day to day basis.
  • PAV8888
    PAV8888 Posts: 13,947 Member
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    Weight trend app or web site may be your friend.

    Your figures as presented are even more wildly variable than what I would expect from must bioimoedence scales, that are too inaccurate and inconsistent to be useful anyway.

    Even the fact that the fat level goes down as weight does is not really giving you information you didn't already know, and at the level of accuracy for most scales. Result says you're 20% fat, with an error rate of 5% in the manner these guys define their error rates, you would be anywhere from 15% to 25% fat.

    Guess what. Your eyeball can do better than 15 to 25%, and most scales claim way worse accuracy than that.

    They are also heavily influenced by recent exercise and glycogen stores.

    In all.... mostly entertainment value and I'm guilty of looking at the numbers even though I know better! 🤷🏻‍♂️

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