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Riddle Me This ... Bioelectrical Impedance Analysis Question


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So I've had this body fat scale for about a year now ... I bought it actually because it also features "hydration" level, or water percentage and I thought it would be a good idea to help keep tabs on dehydration. Anyway I noticed right off that my "body fat percentage" was always rather high -- 28-35% on a consistent basis. Everyone else in my family is around 18-20% but for whatever reason the Bioelectrical Impedance Analysis for me always seems on the high end.

However, last Thursday I noticed that I could stand for a bit without problems. Strange, since I usually get symptomatic quite quickly. But all day I noticed that something had shifted. I could cook a little dinner at the stove without being perched on my stool and I even swept the back patio standing up instead of with my dust broom on my knees. I happened to glance at the scale that night and saw that my body fat was reading at 20%. Down from like 32% the day before. My hydration and weight were roughly the same as the day before. Only the body fat value had changed.

I didn't think much of it, but noticed on Friday that my winning streak continued. I could stand up and walk around the house for short period of time without getting dizzy or dazed. All around it was a good day. Then again, that night i noticed that the scale once again read really low for body fat. Whatever it was that was causing me to feel better seemed to be correlated with whatever the Bioelectrical Impedance Analysis was for body fat on this scale. But again, hydration percent and weight didn't seem to change at all. Strange.

As luck would have it I woke up at 6:30 a.m. on Saturday morning in a full on body flare. My system was shaking, I was back and forth to the bathroom, the heat waves where overwhelming ... all typical for me and my ANS on a really bad day. The flare lasted for a couple of hours, then I slept for a bit and woke up feeling like I had been hit by a truck. I am sure you can relate.

By 3:00 p.m. I could get out of bed and leave my room for a bit ... and you guessed it, my body fat was back up to 29% on that silly scale. So strange since my weight is not moving around more than a pound or two and the hydration level seems consistent by this scales reading. But whatever is triggering these POTS flares and keeping me ostensibly off my feet, seems to have something to do with however the Bioelectrical Impedance Analysis is being measured on this device.

Anyone want to put on their science cap and give this one a guess?

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Bioelectrical Impedance

Body impedance is measured when a small, safe electrical signal is passed through the body, carried by water and fluids. Impedance is greatest in fat tissue, which contains only 10-20% water, while fat-free mass, which contains 70-75% water, allows the signal to pass much more easily. By using the impedance measurements along with a person's height and weight, and body type (gender, age, fitness level), it is possible to calculate the percentage of body fat, fat-free mass, hydration level, and other body composition values. Conventional BIA normally uses underwater weighing as its method of reference.

Using BIA to estimate person's body fat assumes that the body is within normal hydration ranges. When a person is dehydrated, the amount of fat tissue can be overestimated. Factors that can affect hydration include not drinking enough fluids, drinking too much caffeine or alcohol, exercising or eating just before measuring, certain prescription drugs or diuretics, illness, or a woman's menstrual cycle. Measuring under consistent conditions (proper hydration and same time of day) will yield best results with this method.

Because BIA can be affected by body hydration, many professionals may use this method as a means of tracking the hydration status of their patients. This is especially important for athletes who are training or performing, as well as for the chronically ill.

I am betting that your hydration status is what changed. You had more water in your circulating volume than the extravascular tissues (you weren't pooling as badly.) More fluid in the plasma=more blood to the brain! Think back, was your salt intake different, was there something you did differently that would explain why you kept more water inside your blood?

All my thinking cap can come up with... :)

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I suspect the change in the BI (bioelectric impedence) had to do with your hydration.

On another subject, I find it interesting that you refer to "flares" and the opposite, which I suppose can be called "good days". I do not have "flares". In my case, whatever doesn't work properly always doesn't work properly. POTS for me is a chronic disturbance in the functioning of my body without "remissions" or "flares".

I enjoy my life, though, and have become used to my malfunctioning body since I've been this way so long now. I sort of know what I can do and what I can't do and what may happen as a result. Yes, some days seem better than others but I cannot really identify a "flare". I'm in a permanent flare because I cannot adjust to gravity.

Just a sidelight on the terminology used to describe us. Sorry to derail the thread. Carry on.

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On another subject, I find it interesting that you refer to "flares" and the opposite, which I suppose can be called "good days". I do not have "flares". In my case, whatever doesn't work properly always doesn't work properly. POTS for me is a chronic disturbance in the functioning of my body without "remissions" or "flares".

When I use the term "flare" I am usually referring to what is described as a hyperadrenergic flare up of the POTS. I have POTS and debilitating fatigue 24/7 -- but I don't always get those adrenaline storms. Or maybe they are thyroid storms, I have Hashimoto too. I actually don't know what they are, but they are acute and intense and when I can go a whole day without one then yes ... I call that a good day. But last Thursday and Friday were particularly "good days" in that I can't recall in more than two years now having a time when I felt I could stand for even 5 minutes and on those days I could. Seems very odd to me.

I am betting that your hydration status is what changed. You had more water in your circulating volume than the extravascular tissues (you weren't pooling as badly.) More fluid in the plasma=more blood to the brain! Think back, was your salt intake different, was there something you did differently that would explain why you kept more water inside your blood?

That's what I was thinking too. But the "hydration" number didn't change on the scale, on the number that was suppose to represent % of body fat -- which yes I agree can be effected by hydration levels as well. But then why wouldn't the % of Water value be off on the same reading (the scale registers three values, weight, %bodyfat, %water.)

Thanks for thinking with me! This may well be just another mystery or an anomaly that I will never know the answer to. Day in the life ....

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I can't make any sense of it (too brain fogged to try to analyse at the moment).

I hvae these sort of scales too. I notice that my daily weight fluctuations (which I know must be water based) show up as changes in body fat percentage (only by 2% though) as well as changes in water.

I have noticed that no mater how much I drink and even when I was on Fludrocortisone I can never get my body water % above 42-45% the scalse say normal is 55-60% for a female.

Flop

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Bioelectrical must mean that it is sending a current through your body as well, just like nerves would. If our nerves are "impeded" or overfiring, it makes sense that the scale would not read correctly for that portion anyway. It could be reacting to the sodium ions as well. I'm not an electro-chemist so its just a WAG anyway! :blink:

I could tell you if the machine matches your paint color though...

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I could tell you if the machine matches your paint color though...

Can't tell you how much I laughed! Oh. So good. thank you.

Your SWAG got me thinking about how the scale may be misreading from the nerves in our legs overfiring, and I can now at least come up with a theoretical possibility on how one value can change while the other stays the same.

So let's assume the POTS pooling is causing some kind of electrical impedence ...

So when it says my % of body fat is 35 and my hydration is 55% -- BOTH numbers are off by 10-15 percentage points.

In that case it would mean my "actual" body fat is much lower, and my hydration is the Sahara Dessert! Both likely.

So then when I had that really unusual day where I felt more stable on my feet it could have been that my hydration (for some mysterious reason) was higher than normal and this may have contributed to less overfiring in the nerves in my legs.

So now when the scale reads:

22% body fat, the number is more accurate

and the 55% for the hydration (which seemingly hadn't changed) is actually reading a more accurate level of hydration than the day before.

Again ... only a theory. But for the life of me (and my fried brain) I wasn't able to even come up with anything plauseable before. Thanks so much for giving this a noodle with me.

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Just a thought EM, when your body fat % was reading high could you have pooling and the scale saw this as fat. Then when you felt better you weren't pooling and this blood volume was back in circulation and the scale didn't measure this as body fat. I love a good mystery, anyone else with some ideas?

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Because the scales are measuring impedence they measure the resistance to the tiny electrical current going through the body tissues, they don't measure anything to do with the nerves. (You would have to stimulate a nerve directly - like having peripheral nerve tests - not just stand on a plate).

Sorry, still can't answer the question!

Flop

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  • 1 month later...

Just found an article...

http://ndt.oxfordjournals.org/cgi/content/full/21/12/3481

Bioelectrical impedance can be used to predict muscle mass and hence improve estimation of glomerular filtration rate in non-diabetic patients with chronic kidney disease

At the end of the article it states that these scales are completely off for anyone with deranged hydration status. While the article focuses on normals versus CKD patients, it deliberately left out those with "deranged hydration status" because their measurements would be inaccurate. I think that your fluctuating body water is the culprit.

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Just a note here on the morning surges--I get these also. It is kind of like a low and a high, put together. I get up feeling fatigued and draggy all morning, yet fighting the internal buzzing-feeling, feeling hot, and super sensitive upright, POTSY problems. I feel somewhat more settled in the afternoon. And my brain is like mud all morning. My husband knows not to ask for opinions, explanantions, etc. until after lunch.

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The scale is cool, but it's "raw" numbers would be more helpful than any resulting calculations it comes out with (since they're making assumptions that likely don't apply and are "average" norms at best). A more direct "hydration" device might be better, although the notion of measuring impedance in multiple areas of the body (particularly comparing fluctuation in regions known for pooling) is interesting. Your scale likely measures through both legs. This one is targeted at dehydration specifically and they chose the chest:

http://www.hospimedica.com/?option=com_art...temid=266860000

I wish that ER's used this device rather than looking for Orthostatic Hypotension as an indicator of dehydration (or that nuclear study was cheap & trivial). ZOEwi sounds like a fun Wii game too...

In addition to "hydration" of circulatory system, remember there are things balancing intracellular hydration/electrolytes/nutrients/flows such as very tight PH constraints and metabolic needs of each cell type. Traditionally, supplements like creatine will "pump" stuff into muscles specifically and are known for bloat... more subtle things are at play too like "osmolarity gradients" and such, which can set up flow between tissues of the body. All too complicated for me, but fascinating. A person can be well hydrated in blood but dehydrated in tissue, and vice versa.

Was there anything that might have brought on this "good streak"? I know I feel best when my body is magically non-bloated but balanced in hydration. Don't know how to maximize that but it is an observation. When I'm overhydrated I feel sluggish, although that is the doctor recommended state.

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