How much body fat to lose? measurements don't make sense

richardholt2011

I don't thing the measurements and targets I've been given add up - literally. Can anybody explain?

I'm currently about 85 kg and I'm told I should be about 65 kg for my height, to get to an acceptable BMI. So that's 20 kg weight loss. I'm also told (from a machine that I was wired up to yesterday) that about 27% of my body is fat, which is 23 kg. So if I lose the 20 kg of fat, I will have only 3 kg left, which will leave me looking very scary! So what's the answer?

a) I do need to lose 20 kg but only some of that is fat and the rest is... what exactly?
b) I don't need to lose 20 kg at all
c) My body fat at the moment is actually much higher than 27% and the machine was completely wrong

MoreBean13

I would go by bodyfat and not BMI. BMI is not terribly accurate on an individual level, your body fat is a much better predictor for health and disease risk.

nxd10

You lose fat and lean muscle mass with weight loss. If you want to lose more fat and less muscle, you need to exercise. That's what exercise does when you're on a calorie deficit.

Those body fat calculations are wildly inaccurate because they are based on average heights and body builds. Mine range from 20% to 30% depending on the method. But all of them are wrong, because they're based on an average body woman of average height and I'm quite tall and very busty. If you're short for a man your estimates are low, if you're tall, they are high.

BMI is stable, certainly, but not great for measuring individuals because very muscly people look obese according to the numbers. On the other hand, for most of us, getting in the 'healthy' BMI range is a good thing. If you're really muscly, it's obvious you're not fat.

I would shoot for losing that 20 kg you are shooting for. As you do, you will lose a lot of fat and, if you keep exercising, maintain your muscle. That's a good goal.

MoreBean13

You lose fat and lean muscle mass with weight loss. If you want to lose more fat and less muscle, you need to exercise. That's what exercise does when you're on a calorie deficit.

Those body fat calculations are wildly inaccurate because they are based on average heights and body builds. Mine range from 20% to 30% depending on the method. But all of them are wrong, because they're based on an average body woman of average height and I'm quite tall and very busty. If you're short for a man your estimates are low, if you're tall, they are high.

BMI is stable, certainly, but not great for measuring individuals because very muscly people look obese according to the numbers. On the other hand, for most of us, getting in the 'healthy' BMI range is a good thing. If you're really muscly, it's obvious you're not fat.

I would shoot for losing that 20 kg you are shooting for. As you do, you will lose a lot of fat and, if you keep exercising, maintain your muscle. That's a good goal.

What calculations exactly are you referring to? I'm quite confused by this reply.

He said he was hooked up to a machine that gave him body fat, which I took to mean probably some sort of bioimpedence device. I agree that they can be really inaccurate, but probably not 20-30%. They are very sensitive to hydration levels, so having "normal" hydration can be a big deal. But the part I really don't understand is about the average person they're based on- this leads me to believe were talking about different things. The bioimpedence devices work by sending an electrical signal through your body, and the signal passes through your body at different rates through water-based tissue (blood, fluids, muscle) than fat, so it uses the time it takes from one receptor to the other to determine the fat ratio. I'm not sure how being tall or short affects that- your height and weight are taken in to consideration by the device.

To be clear- I'm not arguing for the accuracy of bioimpedence devices, just confused.

But I do stand by my previous answer, bodyfat is a way, way better measure than BMI. You don't have to be a bodybuilder for BMI to be off- its not even close for me, and I am certainly not a bodybuilder.

richardholt2011

Thanks for the replies.

The body fat estimate is from scales at the local gym - the ones which measure (or claim to measure) the amount of body fat that I'm currently carrying, using electric current through the feet. The answer it gave was 23 kg. As I say, if I lose 20 kg of fat I will end up with almost no fat which can't be right. So my guess is that the machine's readings are not just wrong but massively so and that I'm carrying a lot more fat than it suggested.

And indeed that's what my scales at home say - they say my body fat is more like 48% which is scary! If we assume 48% is right then that's 38 kg so I'm kind of aiming to get rid of roughly half of it. Which intuitively feels plausible.

Martucha123

I'd say you have 20 kg to go, you will have plenty of time to worry about it after you drop first 10 kg
and don't expect all lose to come from fat, there will probably be also some muscle loss