Question about body fat %

I was inspired on my weight loss journey to buy a scale and I found one that has a body fat analyzer built into it.  I have had my body fat taken alot in the past and actually estimated it with measurements about 2 weeks ago and got 20%.

I stepped on this thing and it said I was at 30%!  I am 5'6" and weigh 135 lbs.  I am active and eat a fairly good diet at about 1200 - 1500 cals/day.  I thought it may be a fluke but the readings are consistantly the same with a 2% drop over the last week.

Does anyone have any expereince with these scales?  If so, what readings did you get (not numbers but trends) and do you feel they are accurate?  How much does water intake, salt intake and time of day make?  I usually weigh once in the morning.

My Tanita scale routinely measures 5-6% higher than the bioelectrical impedence machine at the gym.  Based on my height, weight, and level of fitness, I tend to believe the one at the gym more. 

Only way I get a number I feel is close to accurate is to wipe my feet with a damp cloth first.

OTOH I doubt you have the tough feet I do-)

Water makes a big difference. The things should read higher early in morning since you've dried out over night. Should be better later.

I wouldn't worry about the actual numbers on the scale. Instead watch the trend. If it dropped 2% that's good-))

Whew!  I feel better.  I see that weighing for body weight will be good in the morning but weighing for bodyfat might be better in the evening. I'll try wiping my feet off before I try it next time.

 I wish that the scale had more information with it about factors leading to an accurate measurement.  It gets frustrating because I am holding steady on bodyweight but the % is changing a little.  If I'm doing something wrong or not getting correct readings due to hydration and the like that sucks.

Most fat analyzers are based on a calculation of weight that is dense. and water. It uses the bmi table to create a body fat count. In my case it is completely wrong. I have the tanita scale. It says I am 30% bodyfat. When measure using calipers I am 22% body fat. My muscle mass is greater than most folks and the scale can not determine the difference between muscle and fat. Most scales shoot an electronic beam into your body via a battery and foot sensors that separates water weight. It then uses a calculator built in, and based off the bmi tables to calculate your "fat".  If your going to weigh with in the measurements of the bmi for height and weight, then the scale is fairly accurate.  Water weight will fluxuate from day to day and your readings of body fat will vary too.  Go to Meso Rx web and look up threads about scales.
Cheers
M
Ps
don't worry keep on eating properly and keep exercising. If that doesn't help then take two asprin and call me in the morning.

Thanx Mike, that was a really good explaination of what I was looking to find out.  It makes sense to me that it won't be as accurate as a caliper test would be.  I guess I'll just have to use it as a ballpark figure.  I'll try your suggestions.  Thanks!

Bea