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Can you use body fat % to calculate ideal weight?


Slimming down the aisle
S: 19st1.5lb C: 18st6.8lb G: 13st0lb BMI: 38.2 Loss: 0st8.7lb(3.25%)
This might sound like a stupid question! But I've been struggle to decide what my end goal will be, I've always been fat so don't know what is normal for me! I'd decided to not really set a goal but stop when I feel comfortable if that makes sense.

Anyway, I was thinking. I went and used one of the weight and body fat machine things so I know what my body fat percentage is now and also how much in weight of my body is fat. So, in theory, if my BF% now is 45% and I want to get it down to in the middle of the healthy range, so say 27%. I could take my weight now minus all the fat I currently have (11st non fat) and add 27% to that for a healthy weight for myself, yes? Does that make sense or does it not work that way? I'd never really thought of it this way before!

I know it doesn't fit with BMI but I don't really place all that much importance in BMI to be honest. I would think BF% is a better way to do it, but I don't know, it's just my thinking. What are your thoughts?
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Les Mills Fitness Freak
S: 10st0lb C: 8st13lb G: 8st3lb BMI: 20.2 Loss: 1st1lb(10.71%)
ive started going by body fat rather than BMI


Loves to post
S: 16st0.0lb C: 12st5lb G: 12st7.0lb BMI: 26.3 Loss: 3st9lb(22.77%)
I can't answer you question Caroline - sorry.

But, I would like to know how you got your body fat measured.

I'd like to find out mine.

Many thanks x


Les Mills Fitness Freak
S: 10st0lb C: 8st13lb G: 8st3lb BMI: 20.2 Loss: 1st1lb(10.71%)
i use the scales at boots


Gold Member
Yes, that will work. I have done the same thing myself (previously - not in the last few years) - mine does seem to completely agree with the BMI scale though.
You may have to keep adjusting it if your exercise and your lean body mass changes.
I've just hopped on my scales and had a go (readings will be inaccurate due to it being the wrong time of day):

Mass = 195.8 lbs BF = 42.6%

Lean Mass % = 100-42.6 = 57.4%
Lean Mass = (195.8 x 57.4)/100 = 112.4 lbs

Mass if BF is 21% =
100-21 = 79% lean mass
(112.4/79) x 100 = 142.3 lbs
my BMI = 23 at that mass (when I have actually been that mass though my BF% was higher)

I would put it on a spreadsheet so that you can see all the projected masses for each BF% and be able to change it easily if your lean body mass changes.

I will be doing that myself when I have lost a lot more fat and am closer to thinking about a final goal - BMI and BF and my eyes all say I am obese at the mo :D
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