Posted by: Warren | 2005/06/06

Body fat %.

Hi there,

Just wanna know if you know how these machines at the gyms measuring body fat % works?I don't trust them.
I've always been exercising and reasonably fit(Mainly cycling and squash)but never to bothered about body fat % and heart rates and all these things.About 4 months ago I started doing weight training and at that stage I measured my body fat %.I did weights twice a week but kept my cardio exercising up as well and I thought it was really going well until I took my body fat % again last week.It went up by about 3%.If thats true I better give up exercising straight away or I'll be dead in 3 years.
Is this at all possible?I must say,I dont follow a spesific diet and I also enjoy a beer now and again but I haven't been indulging any worse in the past 4 than at any other time.
Help me please?

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Our expert says:
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Hi Warren
One problem with those machines is that they do rely on user technique to produce an accurate result. Therefore, the position, the exact settings on the machine would have had to be exactly the same last week as they were a few months ago in order for the reading to be accurate. If this is not the case, then the range in reading can easily be 3%.

As for the machines, they are relatively accurate. Of course, they are not the best, because the cost factor is important, but I would say that they are better than the skinfold method, simply because this relies so heavily on the technique of the measurer (even more than the machines do). The results from the machine have been correlated against some ‘gold standard’ machines and the comparison is very favourable (we are talking 90% similarity). Where the inaccuracies come in is in body builders and people with very high muscle mass, and so if your training in the last few months has caused you to gain quite a lot of muscle, then part of this 3% may be explained by this.

All in all, they are very accurate, but I guess your experience just highlights the problem with machines – they are not perfect and as such, don’t base your training on them too much – if you are getting fit and feel good about training, then just keep it up!

Good luck

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Our users say:
Posted by: Logic | 2005/06/06

I would say that these machines in the gyms are of no accuracy at all. They have to have a base which to work from, and that baes is the :average person". To illustrate, I will use myself as an example. I am 176cm tall and weigh 86kg. According to the machined I am roughly 30% bodyfat. However, I can see all 6 blocks of my stomach and I am a semi-professional sportsman.
The reason for the high BMI is because the "average man" of my height should only weigh around 73kgs.
The measurements do not take muscle into account. They cannot. The machines do not take in-depth analyses.

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