Body fat, BMI, Weight, Where's the water??

[Niecy17]

Where is the water weight calculated? I know it's included in the total weight. Is it in the fat percentage? the BMI? I notice that the more I workout, the higher the body fat the scale shows. Hard to tell if it's the loss of water or muscle that is causing a higher body fat percentage. Does anyone know? sense they didn't include hydration calculation. For an example: If I drank a gallon of water today, how would that be calculated with the way this scale is made?🤔  I have an Aria 2.

[LZeeW]

@Niecy17   You water weight is part of your lean body mass.  Your Aria 2 does not give a separate water weight amount.  Day-to-day changes in your percent body fat are often due to your hydration status.  This is why I weigh myself at about the same time every day.  Sometimes day-to-day changes happen because of limitations in the technology (error).

If you drink that gallon of water throughout the day, your body will hold on to the water you need and your kidneys will make a lot of very dilute urine.  If you drink that gallon all at once, you will be about 8.3 pounds heavier (a gallon of water weighs about 8.3 pounds).  You percent body fat should drop by a little bit, but then you are going to make a whole lot of very dilute urine to keep your electrolyte balance.  Then you should be back where you started.

It's hard to say why your percent body fat is going up as you continue to work out.  Is this a short term change (a week or two) or a longer term change?  Does you diet meet the needs of you workout schedule?  Try weighing yourself under similar conditions every day to see if that makes your %BF numbers more consistent.

Just to clarify, you mentioned BMI.  BMI is a mathematical relationship between height and weight.  Body composition isn't taken into account with a BMI calculation.

[Niecy17]

Hm, you said water is calculated into the lean body mass. How is that
possible? Water retention during a period is not lean mass. It gives a
blubbery appearance.This scale just doesn't show how much water we're
holding in. Water retention is a real problem for me. I have to literally
sweat every day to stave it off. People with inflammatory issues need that
water calculation. I do eat healthy. Thanks for the information 👍☺️💪🏼

[LZeeW]

@Niecy17   Thank you for your follow up comment.  It helps me understand the information you are trying to get.  Fitbit's metrics report percent body fat and everything else totaled together is lean mass.  So lean mass includes muscle, bone, blood, body fluids, edema fluid, etc.  It sounds like lean mass means muscle mass to you.  Muscle is about 80% water.  A human body averages about 60% water.  Even your bones have a certain percentage of water.  The Aria 2 doesn't separate out the water that is a normal part of muscle from the water from water that is edema or the water that is part of blood.  I don't think any scale has the ability to do that.

It sounds like the type of scale you want is a more elaborate body composition scale.  I am not closely familiar with any of those scales.  But a brief search show that some can sync with the Fitbit app.  This Withings - Nokia Body composition scale tells you your muscle mass and percent body fat.  It gives you your water %.  Even with this scale you will need to do some math.  BTW, one of the images gives a number for IMC -- IMC is French for BMI.

I hope this helps.

[Niecy17]

Nope, other scales do have this capability and are far cheaper. Thanks. I
have concluded that the Aria 2 can't show hydration levels. Thanks for
sharing your knowledge. 😊

[MamaCD]

Definitely most water weight is in the fat cells. Like a camel, in times of a lack of water our bodies will pull water from our fat cells. That’s why people can dry fast for a couple of days. 
Fat and water contents in adipose tissue are variable, ∼60-94% and ∼6-36%, respectively (Thomas, 1962).