Who is good at math? HELPPP!!!
Sarie_Bronish
Posts: 255 Member
My friend weighs 187 pounds and is 38% body fat currently.
I know that 38% of 187 pounds = 71 pounds.
This would leave 116 pounds as LBM
She wants to know what she would weigh at 33% body fat. - but I apparently skipped class those days in math class because I cant figure this out after 3 sheets of paper, 100+ equations, and more answers than I care to admit. Help me please!!!
I know that 38% of 187 pounds = 71 pounds.
This would leave 116 pounds as LBM
She wants to know what she would weigh at 33% body fat. - but I apparently skipped class those days in math class because I cant figure this out after 3 sheets of paper, 100+ equations, and more answers than I care to admit. Help me please!!!
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Replies
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cool points if you show your work :P0
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She wants to lose 5%, 38% - 33% = 5%
187lbs x 0.05 = 9.35lb, this is how much she needs to lose.
187lbs - 9.35lbs = 177.65lbs, this is how much she would be at 33% if she loses no muscle in the process.0 -
If her lean mass is 116 pounds and she is at 33% bodyfat and you want to determine her weight X then:
116 + 0.33 * X = X
Solve for X. 57 pounds of fat, 173 pounds would be her bodyweight assuming no loss of lean mass.0 -
are you assuming she only lost fat? If so, it should be fairly easy to figure out a 5% reduction in weight..unless I'm missing something.0
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She wants to lose 5%, 38% - 33% = 5%
187lbs x 0.05 = 9.35lb, this is how much she needs to lose.
187lbs - 9.35lbs = 177.65lbs, this is how much she would be at 33% if she loses no muscle in the process.
But if she is 177.65 pounds at 33% bodyfat her lean mass would be 177.65 - (.33 * 177.6) = 119 which would mean she would have put on 3 pounds of lean mass.
Answer is 1730 -
She wants to lose 5%, 38% - 33% = 5%
187lbs x 0.05 = 9.35lb, this is how much she needs to lose.
187lbs - 9.35lbs = 177.65lbs, this is how much she would be at 33% if she loses no muscle in the process.
But if she is 177.65 pounds at 33% bodyfat her lean mass would be 177.65 - (.33 * 177.6) = 119 which would mean she would have put on 3 pounds of lean mass.
Fair
EDIT: I guess alternatively one could say X= (116/0.67) if assume 116 is constant.0 -
She wants to lose 5%, 38% - 33% = 5%
187lbs x 0.05 = 9.35lb, this is how much she needs to lose.
187lbs - 9.35lbs = 177.65lbs, this is how much she would be at 33% if she loses no muscle in the process.
But if she is 177.65 pounds at 33% bodyfat her lean mass would be 177.65 - (.33 * 177.6) = 119 which would mean she would have put on 3 pounds of lean mass.
Answer is 173
hmm, guess i made a mistake.0 -
If her lean mass is 116 pounds and she is at 33% bodyfat and you want to determine her weight X then:
116 + 0.33 * X = X
Solve for X. 57 pounds of fat, 173 pounds would be her bodyweight assuming no loss of lean mass.
I did the math differently, but came up with the same answer.
1. Assuming LBM should remain constant: lean body mass=weight * (1-%BF).
2. 187*(1-0.38)=X* (1-0.33)-->solve for X
3. 187*0.62=0.67X
4. 115.94/0.67=X
5. 173.04=X=weight at 33% body fat0 -
x - 116 = x(.33)
x - .33x = 116
.67x = 116
x = 1730 -
thank you - yes, I WAYYYYYYYYYYYYYYYYYYYY over thought this, and i shouldve stuck to my gut. I got all twisted up and *kitten* deep in numbers that didnt matter while trying to be accurate.0
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EDIT: I guess alternatively one could say X= (116/0.67) if assume 116 is constant.
Yeah that would be the easy way really then you don't even have to solve for X in the formula I layed out. Of course if you do do the algebra you end up with X = (116/.67) as laid out in what yewbic did. Guess I never showed my work ;-)0
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