Instructions to calculate your goal weight knowing your curr

kikkipoo
kikkipoo Posts: 292 Member
edited October 4 in Health and Weight Loss
Below is the standardized percentages for body fat based on your desired fitness level.

Women (% fat)
Essential Fat 10-12%
Athletes 14-20%
Fit 21-24%
Acceptable 25-31%
Obese 32% and above

Men (% fat)
Essential Fat 2-4%
Athletes 6-13%
Fit 14-17%
Acceptable 18-25%
Obese 25% and above

I was reading an article on determining if your goal weight is realistic or not and came across these instructions on how to calculate your ideal weight for your body based on the fitness level desired. I am a 5'5" woman and always had the magic number 120 in mind, but following this guideline learned it is not realistic at all for my frame. I will use my own weight and bf% to illustrate how to determine the actual ideal goal weight.

My current weight: 158
Current BF %: 29.5%
That means that of my 158 pounds 29.5% of it is pure fat....or 46.61 pounds (158 X .295)
Which means if had zero fat on my body I would still weigh 111.39 pounds in muscle, blood, water, skin, bones, etc. (158 - 46.61)
Since my desired fitness level is more along the lines of Fit rather than the extremely lean athletic type, I will require an additional 21-24% body fat in addition to my base weight of 111.39.
Calculate by taking 100% and subtracting your desired body fat percentage. (100%-21%)=79%
That is the percentage my base weight represents, so if I divide the base weight by that calculated percentage I will get to my ideal weight (111.39 / .79)=141

So, there you have it, my ideal goal weight would be 141 pounds assuming I lose the correct proportion of fat and gain the correct proportion of muscle to achieve a fit 21% body fat.

I just don't like using the BMI to determine a goal weight. It has no impact on fitness or body fat%. I know plenty of slender women who don't exercise and eat junk food, and I would be likely to presume that their body fat percentage barely falls into acceptable range.

***EDITED TO CORRECT THE FORMULA. MY APOLOGIES, I DIDN'T DO IT RIGHT THE FIRST TIME. PLEASE RECALCULATE***
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Replies

  • fit4everyoung
    fit4everyoung Posts: 395
    read later
  • ehunte
    ehunte Posts: 125 Member
    Great to know.. thanks for the info!
  • juliesummers
    juliesummers Posts: 738 Member
    Cool :)
    The only part that's a bit weird to me is that if I take my current weight and subtract (my bf% x my current weight), that base weight number is about ten pounds above my lowest weight at my height so it's not quite fair to say that it's my true base weight.
  • Beezil
    Beezil Posts: 1,677 Member
    Maybe it's because I'm tired or because I suck at math, but I can't put that together in my head to make sense. x__x
    Thanks for posting though, I will try doing this tomorrow after I've slept... lol
  • MinaAriel
    MinaAriel Posts: 138 Member
    How would I figure out what my current BF is?
  • SergeantSunshine_reused
    SergeantSunshine_reused Posts: 5,382 Member
    Love it! Although it is assumed that you will lose at least a little bit of muscle mass, so i rounded down a couple of lbs just in case :]
  • Beezil
    Beezil Posts: 1,677 Member
    Okay maybe I did it wrong but it says my ideal weight would be 110lbs if I wanted 15% bf... lol. There's no way.
  • mindyydnim
    mindyydnim Posts: 7
    bump. Thanks!
  • Heather_023
    Heather_023 Posts: 76 Member
    bump
  • kikkipoo
    kikkipoo Posts: 292 Member
    Muscle weight has to come to play in there somewhere as well (I presume current muscle counts towards base since it can't count towards body fat), but that's where I've been trying to figure it out more. I know I want to gain muscle...I'm weak and have very little muscle definition. So, when I say I need to lose a certain number of pounds, I have to be very specific to say that those pounds loss come from my fat stores and not muscle. Or I may have to accept that I need to lose higher pounds of fat but gain extra pounds of muscle. Clearly it's still not an exact science, but it does put some perspective out there to some of us who have been trying to obtain the unrealistic dream.

    Bottom line, when I weigh a 141 pounds I intend on going back into the trainers office and using their body fat percentage calculator again to see that I am at 21%. If I'm not, then the ratio of fat lost to muscle gained will need to continue.
  • kgillikin
    kgillikin Posts: 191 Member
    Okay. I am bad at math. I currently weigh 136lbs and am 5ft tall. So how do I apply this formula to me.
  • karinaes
    karinaes Posts: 570 Member
    this doesn't quite work for me.. unless i did it wrong. lol

    i was just being silly because i'm pretty much at where i've wanted to be

    so, i'm 123.5x.16= 19.76 of fat weight
    123.5-19.76= 103.74 lbs (no fat whatsoever theoretically)

    103.74x .16= 16.60 (16% is what i'm at already)
    so,
    103.74+16.60= 120.34

    lol.. just makes no sense! ...i'm 123.5 with 16% bf... if my desired bf% is 16%, then shouldn't my weight still be 123.5 ? hahahaha.. again, i'm just being silly. thought i'd trip people out.
  • Lindz2323
    Lindz2323 Posts: 261 Member
    I'll definitely look into this tomorrow! Thanks for sharing!
  • servilia
    servilia Posts: 3,452 Member
    Since my desired fitness level is more along the lines of Fit rather than the extremely lean athletic type, I will require an additional 21-24% body fat in addition to my base weight of 111.39.
    Calculate by taking your base weight and multiplying it by the desired body fat percentage. (111.39 X .21)=23.39
    That is the weight in fat that I should have on my body in addition to the base.
    (111.39+23.39)=134.78.

    Your formula breaks down in the end. It's hard to explain why in words at 1:20 am but look - you're saying you want 21%BF right? The problem is, that you're figuring out the equivalent in absolute pounds of fat by multiplying the desired BF% (21) by the base weight (the lean body mass). This doesn't give you an overall BF% of 21% in the end, it gives you 17.
    23.39/134.78 = 17.35% (not 21%)

    The correct way to do this is 111.39 (this is gonna be your lean body mass) DIVIDED by 79 (this is the percentage of your final weight that's gonna be lean body mass - ie 100-21) multiplied by 100.
    141 is the result
    You can double check.
    111.39/141 = 79 (your lean body mass percentage). This should already tell you this is the right answer but if you need further explanation:
    141-111.39 = 29.61 (this is your lbs of fat)
    29.61/141 = 0.21 IE 21%, your desired body fat percentage.
  • kikkipoo
    kikkipoo Posts: 292 Member
    You need to know your current body fat %. There are scales that can calculate it for you, but the handheld devices that the trainers use at the gym is the most accurate short of doing a water disbursement test. You don't have to pay for a personal trainer to get them to calculate this for you. Just tap one on the shoulder and ask if they have a minute to help. The trainer I talked to said to do it about every 30 days to get an accurate picture of your progress. If your bf% is going down but the pounds haven't really been significant on the scale...good news, you're gaining muscle.
  • kikkipoo
    kikkipoo Posts: 292 Member
    Oh, wow! I stand corrected! Thank you. Your math makes total sense. I will edit my formula in the original post.
  • judykritikos
    judykritikos Posts: 161
    I really have a hard time believing that a 5'5" person should be 134 pounds. That sounds almost stick-like.
    My Vitality program has me at 146 lbs on my 5'4" frame to be "normal" in my BMI - and I saw his calculation sheet.
    146 would have me in a size 10.
    So 134 on a 5"5" person is almost anorexic. That would rougly be a size 6-8. That's just me thinking.....
  • karinaes
    karinaes Posts: 570 Member
    hahahahahaha.. that is a totally unrealistic equation because every BODY is different. and even if you desire a certain bf%, doesn't necessarily mean you have to weigh a certain number..
    123 is already too low for me.. can't imagine being 120 .. i'm 5' 3.5" tall
  • servilia
    servilia Posts: 3,452 Member
    I really have a hard time believing that a 5'5" person should be 134 pounds. That sounds almost stick-like.
    My Vitality program has me at 146 lbs on my 5'4" frame to be "normal" in my BMI - and I saw his calculation sheet.
    146 would have me in a size 10.
    So 134 on a 5"5" person is almost anorexic. That would rougly be a size 6-8. That's just me thinking.....

    I don't see what's wrong with a 5'5" person being 134lbs. Sounds normal to me. I'm 5'9" and 137lbs and certainly not anorexic. Although as most people know, anorexia is a mental disorder and you don't get diagnosed based on how much you weigh :yawn:
  • servilia
    servilia Posts: 3,452 Member
    Oh, wow! I stand corrected! Thank you. Your math makes total sense. I will edit my formula in the original post.

    No problem it happens to everyone :)
  • juliesummers
    juliesummers Posts: 738 Member
    I really have a hard time believing that a 5'5" person should be 134 pounds. That sounds almost stick-like.
    My Vitality program has me at 146 lbs on my 5'4" frame to be "normal" in my BMI - and I saw his calculation sheet.
    146 would have me in a size 10.
    So 134 on a 5"5" person is almost anorexic. That would rougly be a size 6-8. That's just me thinking.....

    Ummm I'm 5'6" and my highest weight ever ever ever was 122 after months of not exercising and not watching my portion sizes.
    134 is not at all underweight for someone at 5'5"!! Every body is different.

    ps. Anorexia is an all-encompassing disorder -- not a weight.
  • Beezil
    Beezil Posts: 1,677 Member
    I really have a hard time believing that a 5'5" person should be 134 pounds. That sounds almost stick-like.
    My Vitality program has me at 146 lbs on my 5'4" frame to be "normal" in my BMI - and I saw his calculation sheet.
    146 would have me in a size 10.
    So 134 on a 5"5" person is almost anorexic. That would rougly be a size 6-8. That's just me thinking.....

    Ummm I'm 5'6" and my highest weight ever ever ever was 122 after months of not exercising and not watching my portion sizes.
    134 is not at all underweight for someone at 5'5"!! Every body is different.

    ps. Anorexia is an all-encompassing disorder -- not a weight.

    This. I'm 133lbs at 5'7 and certainly not anorexic. My next goal is 120. Still within a healthy range for my BMI.
  • AdrienneinTO
    AdrienneinTO Posts: 111 Member
    I really have a hard time believing that a 5'5" person should be 134 pounds. That sounds almost stick-like.
    My Vitality program has me at 146 lbs on my 5'4" frame to be "normal" in my BMI - and I saw his calculation sheet.
    146 would have me in a size 10.
    So 134 on a 5"5" person is almost anorexic. That would rougly be a size 6-8. That's just me thinking.....

    Ummm I'm 5'6" and my highest weight ever ever ever was 122 after months of not exercising and not watching my portion sizes.
    134 is not at all underweight for someone at 5'5"!! Every body is different.

    ps. Anorexia is an all-encompassing disorder -- not a weight.

    Thanks for the information, everyone!

    BTW, I am currently 138 lb, at a size 8, almost a size 6, and am most certainly not anorexic. I could stand to lose a few more lbs. It does very much depend on body type. :)
  • jennp1313
    jennp1313 Posts: 29
    just throwing this out there: bone density and breast size factor in to ideal weight as well. Everyone is different in these two areas, obvously, so that might account for the discrepencies in weight/heighth ratios. also, older people tend to have slightly less dense bones, so they are "allowed" a higher body fat percentage.

    12311475.png
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  • kikkipoo
    kikkipoo Posts: 292 Member
    this doesn't quite work for me.. unless i did it wrong. lol

    i was just being silly because i'm pretty much at where i've wanted to be

    so, i'm 123.5x.16= 19.76 of fat weight
    123.5-19.76= 103.74 lbs (no fat whatsoever theoretically)

    103.74x .16= 16.60 (16% is what i'm at already)
    so,
    103.74+16.60= 120.34

    lol.. just makes no sense! ...i'm 123.5 with 16% bf... if my desired bf% is 16%, then shouldn't my weight still be 123.5 ? hahahaha.. again, i'm just being silly. thought i'd trip people out.

    Yup!!! I screwed up in the math. So, doing it correctly you're breakdown would be
    Essential body fat- 115.3-117.9 pounds
    Athletic body fat- 120.6-129.7 pounds
    Fit body fat-131.3-136.5

    But it's good to know you're right where you need and want to be, eh?
  • kikkipoo
    kikkipoo Posts: 292 Member
    I really have a hard time believing that a 5'5" person should be 134 pounds. That sounds almost stick-like.
    My Vitality program has me at 146 lbs on my 5'4" frame to be "normal" in my BMI - and I saw his calculation sheet.
    146 would have me in a size 10.
    So 134 on a 5"5" person is almost anorexic. That would rougly be a size 6-8. That's just me thinking.....

    I"m a size 10 now and it's not sufficient for me. I would love to be a 6. If I were a chubby chaser then I might say a size 6 was stick-like but otherwise it has been a standard ideal size for many women over the years. My bmi info tells me I can healthily range anywhere from 115-150. To me that is just entirely too vague.
  • Lyadeia
    Lyadeia Posts: 4,603 Member
    According to this, my goal weight should be between 115-120. That seems about right, I think. Too bad that means I have to lose 29 more pounds to get there. I'll keep on working at it though. I am 5'5" tall and want to be between 12-17% body fat...12ish for figure comps. and 17ish otherwise.
  • Lyadeia
    Lyadeia Posts: 4,603 Member
    I really have a hard time believing that a 5'5" person should be 134 pounds. That sounds almost stick-like.
    My Vitality program has me at 146 lbs on my 5'4" frame to be "normal" in my BMI - and I saw his calculation sheet.
    146 would have me in a size 10.
    So 134 on a 5"5" person is almost anorexic. That would rougly be a size 6-8. That's just me thinking.....

    ALMOST ANOREXIC??? Please tell me that was a sick joke.

    I am 5'5" tall. Look at my profile picture. My wedding dress was a size 8. I weighed 138 pounds. Look at my diary. I eat 1550 or so calories per day. Do I look "anorexic" to you??? I had about 27% body fat, too. Sheesh...
  • TrainingWithTonya
    TrainingWithTonya Posts: 1,741 Member
    The corrected formula in the OP is the formula we use in my exercise physiology lab to determine ideal body weight. The confusion for some comes in thinking that it is all fat lost when we lose weight. This formula is only correct if you maintain your current lean body mass while losing. Most people don't maintain their lean body mass while losing weight, so I would classify it as a "goal ideal weight" instead of an absolute ideal body weight because it can and will change depending on if you add or lose muscle.
  • bluecal822
    bluecal822 Posts: 21 Member
    How would I figure out what my current BF is?

    bump
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