BMI vs percent body fat????

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hrsj022
hrsj022 Posts: 41 Member
in Health and Weight Loss
Even before I started MFP I went to the Doctor. I got weighed he looked at the chart and said no way you weigh that...the nurse must have mixed this up. So the Doctor weighs me and is shocked. He said well you don't look your weight...anyway fast forward to today...on the BMI I'm severely Obese a 42 on the percent of body fat I'm at 28% so it's supposed to be considered acceptable? So which is more important I'm confused!!! Help
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  • LKArgh
    LKArgh Posts: 5,179 Member
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    Unless you are an athlete, and in a sport that helps you build a lot of muscle, you are morbidly obese and the fat percentage measurement is inaccurate. There is no way a BMI of 42 places you anywhere close to healthy weight. Even if you are a bodybuilder.
  • clafairy1984
    clafairy1984 Posts: 253 Member
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    I'm in a similar situation to yourself. My BMI puts me a few points off of obese. However, my Body fat % is 35, and should be max 30, which i dont think is too bad considering what i used to weigh.I have lost over 4 stone, workout 5/6 days a week, including regular weight training. I have gone from a Uk size 20 to a UK size 10-12. There is no way i will accept my BMI of almost obese at a bloody size 10!! Similarly my partner, who works out with me, has a body fat % at the lower end of his 'healthy' range, i literally cannot pinch any fat anywhere on him, and yet he is also deemed as obese. I still weigh in, but dont pay as much attention to it, i now measure my fat % once a week at the gym and use that to track my progress.
  • shadow2soul
    shadow2soul Posts: 7,692 Member
    edited March 2016
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    How did you come up with the BF% ?

    I'm a little skeptical on the BF% OP. If you were using a scale remember that method is considered highly inaccurate for determining BF%. Dexa scan, bod pod, and dunk tests are considered to be the most accurate methods.
    My husband gets a reading of 10% from the scale he uses, but a caliper measurement by a trainer at the gym puts him closer to 20%. Looking at him, I think the 20% measurement is closer to being accurate.
  • clafairy1984
    clafairy1984 Posts: 253 Member
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    Scales at gym
  • samhennings
    samhennings Posts: 441 Member
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    BMI is BS, pay it no mind.
  • Mystical64
    Mystical64 Posts: 108 Member
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    When I first started I was obese according the charts as well. And that was over a year ago. But now, I'm down to 23% bf. Just keep going and use the scale at the gym as a tool. It's more than likely inaccurate, however if it goes down that's great. You know you are working in the correct direction.

  • hypnobabe67
    hypnobabe67 Posts: 2 Member
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    the body fat percentage scales are notoriously inaccurate. If they are ones you just stand on they only measure the lower half of you, even the ones used by the gym that do your whole body are not that accurate, it depends on how hydrated you are etc. The only real way to get a body fat % is to get a PT or Dr to use calipers to measure. As for BMI its an ok rule of thumb unless your an athlete with lots of muscle.
  • dollydiva2
    dollydiva2 Posts: 71 Member
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    I had a check at the gym the other day that put my BF% at 40% (with one of those handheld gadgets)!!

    My BMI is 24.8 so I'm in healthy range and calipers method and tape measure method put me around 26% BF

    I won't be touching their gadget again!
  • Packerjohn
    Packerjohn Posts: 4,855 Member
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    samhennings wrote: »
    BMI is BS, pay it no mind.

    False. It is a decent indicator for around 80% of the population. If you have lifted for a long tI'm and/or do manual labor someone with a bmi over normal may have an acceptable bodyfat percentage. Otherwise probably not.
  • robininfl
    robininfl Posts: 1,137 Member
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    shadow2soul wrote: »
    How did you come up with the BF% ?

    I am wondering the same thing. A BMI of 42 at an average height of 5'6" is 260lb. I don't think you could have 200lb of lean body mass, unless you have bones made of lead or something that doesn't make sense.
  • tryin2die2self
    tryin2die2self Posts: 207 Member
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    I would toss BMI out the window. It may be good for 80% of the population but body fat percentage works for 100% of the population. That said, getting spot on accurate BF% is pretty hard to do unless you use calipers or water displacement. The electric current/resistance body fat calculators can be pretty accurate to a complete waist of time. You can get within +/- 1.5 BF% with honest measurements. I say honest because you need to measure in the right place, every time to get accurate results. I also recommend you get someone else to tape you. That way your movements are not throwing off the results. Take three measurements of each area, average the results and the plug that into the calculator.

    All of the measurements are also great NSVs for those looking to gain muscle and/or lose weight. Dropping an inch in the waist or hips is cause for more celebration than just losing a few pounds.
  • yusaku02
    yusaku02 Posts: 3,476 Member
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    hypnobabe67 wrote: »
    the body fat percentage scales are notoriously inaccurate. If they are ones you just stand on they only measure the lower half of you, even the ones used by the gym that do your whole body are not that accurate, it depends on how hydrated you are etc. The only real way to get a body fat % is to get a PT or Dr to use calipers to measure. As for BMI its an ok rule of thumb unless your an athlete with lots of muscle.
    ^This.

    I've stepped on a scale at a friend's place that measures body fat %. It told me I was 28% when at the time I was probably between 12-14%.
    A month ago I started cutting for summer and tried measuring my starting weight and body fat. I used a thing at the grocery store that you sit on and put your palms out onto a few metal strips and I'm guessing it sends electrical pulses through you. That told me 24%. Not 1 hour later I used caliphers at home and depending on the formula used I was given anywhere from 12% - 18%. Eyeballing myself I think 15-18% was the most accurate but unless it's professionally done the results are going to be all over the place.

    I agree, BMI is fine for non-athletes. Right now my BMI is 26 which puts me in the overweight category but a quick look through my photos on this site will tell you that I'm certainly not overweight.
  • kshama2001
    kshama2001 Posts: 27,982 Member
    edited March 2016
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    hrsj022 wrote: »
    Even before I started MFP I went to the Doctor. I got weighed he looked at the chart and said no way you weigh that...the nurse must have mixed this up. So the Doctor weighs me and is shocked. He said well you don't look your weight...anyway fast forward to today...on the BMI I'm severely Obese a 42 on the percent of body fat I'm at 28% so it's supposed to be considered acceptable? So which is more important I'm confused!!! Help

    What's your frame size? http://www.myfooddiary.com/Resources/frame_size_calculator.asp

    I have a large frame and the only time I've had a BMI of 24 was after 6 weeks of under-eating and over-exercising during Boot Camp.

    That said, with a BMI of 42 you're still overweight, but perhaps not Severely Obese if you do have a large frame.

    Where'd you get your body fat tested? Many ways to measure this are not considered accurate. http://dailyburn.com/life/health/how-to-measure-body-fat-percentage/
  • Scandinavianblonde
    Scandinavianblonde Posts: 22 Member
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    Not to hurt your feelings but I do think there is SOME correlation from bmi to a rough body fat percentage.. Like the only cases where bmi is way off are in professional athletes ( or competitive athletes) aka 2-5% of the population, and in taller folks ( like me who's 5'10). I have found when my body fat goes down so does my bmi. People will always say you look like you weigh less because everyone lies about their weight.. No one ever guesses I weigh 130s or 140s because I'm so tall and athletic. Lots of people are frauding on their weight and it gives lots of people like you false confidence.
  • Scandinavianblonde
    Scandinavianblonde Posts: 22 Member
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    Also it's possible he saw the weight and was shocked at such a high number. One time as a child I gained ten pounds and the number was quite high and my doctor had a similar reaction. A bmi of 42 is very overweight might even be morbid obese. There's a chance he doesn't get morbid obese patients day to day and was up equipped to handle it
  • kshama2001
    kshama2001 Posts: 27,982 Member
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    Scandinavianblonde wrote: »
    Not to hurt your feelings but I do think there is SOME correlation from bmi to a rough body fat percentage.. Like the only cases where bmi is way off are in professional athletes ( or competitive athletes) aka 2-5% of the population, and in taller folks ( like me who's 5'10). I have found when my body fat goes down so does my bmi. People will always say you look like you weigh less because everyone lies about their weight.. No one ever guesses I weigh 130s or 140s because I'm so tall and athletic. Lots of people are frauding on their weight and it gives lots of people like you false confidence.

    I had a similar experience when I was doing online dating and most of the men were adding a few inches to their height. However, the OP is talking about a doctor seeing patients who weigh on a medical scale in his office, not people self reporting their weight.
  • rpachigo
    rpachigo Posts: 96 Member
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    BMI works for the vast majority of the population. Ignore at your own risk.
  • kimny72
    kimny72 Posts: 16,013 Member
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    OP, without providing your height and weight, we would only be guessing. Also, how did you measure your body fat %? The two numbers you provided seem really hard to reconcile.
  • cwolfman13
    cwolfman13 Posts: 41,874 Member
    edited March 2016
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    They should be used in conjunction with BF% being more specifically important to an individual, however, your numbers just don't jive at all. It is not uncommon for people who train, to be overweight by BMI standards but to be well within a healthy BF%...but there's way too much disparity in your numbers, even if you were a professional body builder.

    Just as an example, I have a BMI of 26.4 which puts me just over the line of overweight...I'm somewhere between 12-14% BF which is well within a healthy range for a male of my age....but there's just not a huge disparity here between my BMI and my BF%...to get to the highest end of a healthy BMI, all I'd need to do is drop about 9 Lbs...which would also have me very lean...probably 8-10% BF.

    Something isn't right with your numbers...my guess is that you are not measuring your BF% properly.

    By and large, BMI is a pretty good indicator for the vast majority of the population...and even if you train, unless you're an elite athlete of body builder or something, there shouldn't be a whole lot of disparity between what BMI is telling you and your BF%.

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