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  1. #1
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    Is BMI (Body Mass Index) completely inaccurate?

    So I've finally gotten the motivation to loose those extra pounds as I get into my 30s. I was 215 pounds back in April, now I'm 200. I'm eating around 1500-1800 calories per day, mostly eating fruit, veggies and lean protein and also riding 2-4 times per week. I'm riding faster, sleeping better and have tons more energy - feeling good.

    I'm curious about what healthy weight I should get down to. I'm 6'1", 32 years old, have a 34 inch waist and I'm trying to get to 185 lbs. I plugged my stats into a BMI calculator and it says I'm "overweight." So then I put my goal weight of 185 and that leaves me at the highest end of "normal" weight. WTF? How could anyone at my height with a 34 inch waist be "overweight?"

    Just wondering how people determine their "healthy" weight? Its seems the BMI is pure crap. I'm also sort of shocked that people still use this system to determine healthy weight. According to the BMI, I should weight about 170 lbs, which seems like an unhealthy weight for a guy my size. I'm curious what people's thought are about this.
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    6'2" and hover around 220. When i get down to 205 i show abs and people are asking me if im sick (face gets all hollow looking). According to those charts i am currently classified as obese and would still be overweight at 205.

    Heres the thing, those charts do not account for muscle development. According to my father (a retired health care professional) this is on purpose. The difference between fat and muscle to your heart is 0. Your heart is required to push blood through your body mass and no matter what conditioning level you are at, more mass = more mass. According to pops a 260lb body builder at 3% body fat is at the same risk of heart failure as a 260lb couch potato.

    Take a BMI chart with a grain of salt. You know your realistic body weight goals better than a piece of paper.

  3. #3
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    i dont even think about it. just look in the mirror and judge how your cloths fit.
    fap

  4. #4
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    Quote Originally Posted by BigRingGrinder View Post
    Heres the thing, those charts do not account for muscle development. According to my father (a retired health care professional) this is on purpose. The difference between fat and muscle to your heart is 0. Your heart is required to push blood through your body mass and no matter what conditioning level you are at, more mass = more mass. According to pops a 260lb body builder at 3% body fat is at the same risk of heart failure as a 260lb couch potato.

    Take a BMI chart with a grain of salt. You know your realistic body weight goals better than a piece of paper.
    This makes a lot of sense, never thought about it this way.
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    not completely. it does work how it was intended. as big ring pointed out there was just major flaws in the logic.

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    BMI is a source of huge contention.

    For most people, BMI is reasonable (with the obvious exception being bodybuilders and other athletes who carry a lot of muscle-mass).

    I'm a 40-year-old, 5'10" tall woman. My healthy weight range (according to the Halls MD BMI recomendations) is 132 - 174 lbs. That is a huge range. I have a small frame, and I'm 135lbs.

    You might like to have a body composition analysis done, VTSession. While I think it is highly unlikely that we're in the same city, I utilize the testing services of this company: TCR Sport Lab. You may be able to find a similar lab.

    The specific tests I have done twice a year are "Body Composition" and "RMR" (resting metabolic rate). The tests have been a tremendous asset to me. They've eliminated a lot of the frustration in not knowing what was the right course of action for me, and have made the intangible much more tangible.
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  7. #7
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    Quote Originally Posted by NicoleB View Post
    i dont even think about it. just look in the mirror and judge how your cloths fit.
    This coming from "stringbean" herself.

    But you are,right Nicole that's how I have always done it as well.
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  8. #8
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    Is BMI (Body Mass Index) completely inaccurate?

    I go by body fat % numbers to gauge my improvement.

    Not only does bmi fail to account for lean muscle, it fails to account for bone density. Different types of tissue DO affect the heart and blood differently. Fat tissue has way more blood supply than muscle. Bone has very little blood supply comparatively.

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    % Body fat is the key...

    But it is difficult to measure

    See attached files for various ways to estimate bady fat..

    I like the neck measurement, waist measurement, heigh and weight...simple and preety close...

    Body Fat Calculator 6 formulas to calculate body fat percentage

    It is called the tape method

  10. #10
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    Fwiw @ 6'1" imo 170# is too skinny. As stated, bmi is whack because it depends on where your body likes to store fat. Nicole mentioned the best, easiest, most accurate, and free way to measure and that's your clothes.
    For me, once I get into single digit bmi my endurance falls off. I like to keep it around the point where i show a 4 pack instead of 6 and couldn't care less about what others find to be true and important. Plus you only live once and I like to eat whatever I want, at least sometimes.
    Round and round we go

  11. #11
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    Quote Originally Posted by BigRingGrinder View Post
    6'2" and hover around 220. When i get down to 205 i show abs and people are asking me if im sick (face gets all hollow looking). According to those charts i am currently classified as obese and would still be overweight at 205.

    Heres the thing, those charts do not account for muscle development. According to my father (a retired health care professional) this is on purpose. The difference between fat and muscle to your heart is 0. Your heart is required to push blood through your body mass and no matter what conditioning level you are at, more mass = more mass. According to pops a 260lb body builder at 3% body fat is at the same risk of heart failure as a 260lb couch potato.

    Take a BMI chart with a grain of salt. You know your realistic body weight goals better than a piece of paper.
    This makes no sense and is very overly simplified. If you have visceral fat, fat stored around your internal organs, your heart is at jeopardy because of increased blood pressure. As I understand it, this is mostly because your kidneys are a soft tissue. If the internal pressure due to visceral fat is high, the kidneys increase the blood pressure to maintain an equilibrium. This is not the same as having fat externally or muscle. Not to mention that to maintain muscle you must work out, which is recommended for a strong, healthy, heart.

    I've seen people who are on the low end of the BMI based on weight and end up being obese after the percent body fat is measured because they were fat and bones with little muscle.

    All things being equal, strong trumps all.

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    and the types of tissue your body is composed of affect your blood volume enormously. if you are fat, you have a very high blood volume relative to your weight. if you are lean, your blood volume will be low relative your weight.

    Fat tissue itself has a high volume as per its weight (low density) whereas muscle tissue is much more dense. A lean, strong person can weigh more and have a higher surface area relative to their body volume than a fat person at a similar weight. Simple physics as a result of this affects the amount of calories you burn at rest. A person with a higher surface area to volume ratio will need to burn more calories to maintain the same body temp (especially when it's colder) than someone with a lower ratio. Fat is all about energy conservation. It's why animals that hibernate pack on fat prior to the winter. It not only serves as a source of energy but also insulates the body and allows the animal to expend less energy to maintain its body temperature.

    There is a lot going on and I only scratched the surface. Poe pointed out another major difference between the way the body reacts to fat vs. muscle. The basic idea here is that in no way are muscle and fat equivalent, which makes bmi pretty much useless.

    Apparently there are some adjusted bmi calculations out there that are an attempt at adjusting that number a little bit based on other measurements, but I still find it flawed. My father had an idiot trainer giving him some horrible advice on diet and other things based on some kind of adjusted bmi.

    I have a Tanita scale that reports body fat %, but I also occasionally get caliper measurements for a little more accurate readings. Caliper measurements are nice because they look at common areas that the body deposits fat (abdomen, thighs, arms). Mostly I am where I want. I do, however, have a little more fat in my abdomen than I'd like. Like theMeat, I think I'd be happy with a 4 pack. I'm not far off of that. Maybe another percentage point or two drop in body fat % would get me there.

  13. #13
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    Quote Originally Posted by NateHawk View Post
    I have a Tanita scale that reports body fat %, but I also occasionally get caliper measurements for a little more accurate readings. Caliper measurements are nice because they look at common areas that the body deposits fat (abdomen, thighs, arms). Mostly I am where I want. I do, however, have a little more fat in my abdomen than I'd like. Like theMeat, I think I'd be happy with a 4 pack. I'm not far off of that. Maybe another percentage point or two drop in body fat % would get me there.
    How does the Tanita compare to the caliper measurements? If you're not far off a fourpack, I'd guess you body fat percentage at 12-15 percent. I have been working under the assumption that the leaner someone becomes, the less accurate bioelectrical impedance analysis is.
    Know your limitations, and then defy them.

  14. #14
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    Quote Originally Posted by neacail View Post
    How does the Tanita compare to the caliper measurements? If you're not far off a fourpack, I'd guess you body fat percentage at 12-15 percent. I have been working under the assumption that the leaner someone becomes, the less accurate bioelectrical impedance analysis is.
    The Tanita puts me in that range. The software that comes with it (the scale itself has no display) gives a setting for body type (Athlete or Standard). If I tell it Standard, it puts me at around 20%, which can't be right for my body type. If I tell it Athlete, it puts me around 11%, sometimes closer to 10%. My body fat is disproportionately put into my abdomen as the result of 9 months of prednisone a number of years ago that blew me up like a balloon. I actually WAS at 20% body fat for a time, confirmed by calipers. It did not take long to start regaining muscle tone and mass and thin up significantly across my body. My abdomen is the last vestige of that treatment. I haven't had a caliper measurement taken recently. I relocated to a new state and haven't found competent, reasonably priced folks yet.

    At one point in my life, I am pretty sure I was around 6% body fat, or possibly less. I had an 8 pack back then. I was a skinny mofo with not much muscle mass. I don't ever want to be at that point again.

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    Nate, 3 great ways to get rid of the stubborn body fat. You know, the first to develop and last to leave body fat.
    -Eat smaller meals more often @ around a 4:1 carbs/protein ratio. Keeps your metab up, muscle fed and avoids muscle from being consumed as energy. Which is good again because muscle mass, or the more you have, helps to speed metab even at rest. Shot for a small meal every 2 1/2 - 3 hours. This method may take a week/month to get the full advantage depending on how long, if at all, your body takes to decides it doesn't have to store, or store as much, for times of need anymore.
    -Do cardio for 20+ minutes in the am when you wake before eating, or after a strenuous work out. This will get you cutting into stores right away as opposed to at other times when you have to use up food energy first.
    -Cycle carbs. Either carbs am no to low carbs pm, or carbs for a few days and no to low carbs for a few more.

    If you stick to a decent diet and exercise routine at all other times and aspects, this can really help some maintain and even gain muscle while loosing fat.
    -Nother thing I'll throw out there is that your body changes more and faster when shocked to do so. So when you start a new exercise routine, diet, or schedule, shock the bod with some more intense than usual exercise to help spark that change.
    YMMV
    Round and round we go

  16. #16
    see me rollin, they hatin
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    Quote Originally Posted by DIRTJUNKIE View Post
    This coming from "stringbean" herself.

    But you are,right Nicole that's how I have always done it as well.
    i wasnt always a stringbean! i remember when i hovered at the upper end of normal. we're talking, a tenth of a point. Then it told me i was underweight at one point. i'm normal now. (for my height.)
    fap

  17. #17
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    Good for you, sounds like you're working hard to get that weight off. Don't be in too much of a hurry, you'll end up losing muscle....

    The BMI is an old out dated system created way back when the 5'9" average man's "ideal" weight was like 175.

    When I was at 5% BF I still was technically obese for my height/weight/age

  18. #18
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    Quote Originally Posted by theMeat View Post
    Nate, 3 great ways to get rid of the stubborn body fat. You know, the first to develop and last to leave body fat.
    -Eat smaller meals more often @ around a 4:1 carbs/protein ratio. Keeps your metab up, muscle fed and avoids muscle from being consumed as energy. Which is good again because muscle mass, or the more you have, helps to speed metab even at rest. Shot for a small meal every 2 1/2 - 3 hours. This method may take a week/month to get the full advantage depending on how long, if at all, your body takes to decides it doesn't have to store, or store as much, for times of need anymore.
    -Do cardio for 20+ minutes in the am when you wake before eating, or after a strenuous work out. This will get you cutting into stores right away as opposed to at other times when you have to use up food energy first.
    -Cycle carbs. Either carbs am no to low carbs pm, or carbs for a few days and no to low carbs for a few more.

    If you stick to a decent diet and exercise routine at all other times and aspects, this can really help some maintain and even gain muscle while loosing fat.
    -Nother thing I'll throw out there is that your body changes more and faster when shocked to do so. So when you start a new exercise routine, diet, or schedule, shock the bod with some more intense than usual exercise to help spark that change.
    YMMV
    Yep. I may not be doing those things as religiously as I could, but I am getting the belly fat to melt away. It's not fast, but it is going. This time of year is probably my least active because it's also the wettest month of the year here and the trails don't have many dry days. I get out when I can. Once the trails start getting more dry spells longer than a day or two, I'll be able to get more riding in and get my calorie burn up and accelerate some of that fat loss. By the end of the season, I'd like to meet that 1% to 2% body fat percentage drop I mentioned earlier.

    Wintertime is when I tend to do more strength work and vary the workout more. I made good progress this year. I did a pretty rigorous core workout this past winter and while I may not have changed weight much, I noticed significant trimming around my core and started to see some muscle definition again. That made me happy.

  19. #19
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    Quote Originally Posted by NateHawk View Post
    The Tanita puts me in that range. The software that comes with it (the scale itself has no display) gives a setting for body type (Athlete or Standard). If I tell it Standard, it puts me at around 20%, which can't be right for my body type. If I tell it Athlete, it puts me around 11%, sometimes closer to 10%. My body fat is disproportionately put into my abdomen as the result of 9 months of prednisone a number of years ago that blew me up like a balloon. I actually WAS at 20% body fat for a time, confirmed by calipers. It did not take long to start regaining muscle tone and mass and thin up significantly across my body. My abdomen is the last vestige of that treatment. I haven't had a caliper measurement taken recently. I relocated to a new state and haven't found competent, reasonably priced folks yet.

    At one point in my life, I am pretty sure I was around 6% body fat, or possibly less. I had an 8 pack back then. I was a skinny mofo with not much muscle mass. I don't ever want to be at that point again.
    Being skinny is overrated. There is a lot of evidence that being a bit overweight is better than being underweight.

    People mix up being healthy with being fit. Some of the healthiest people are not fit and some of the fittest people are not healthy. Not that they are mutually exclusive but one has to keep it in mind when developing goals. The physical level for being healthy is far below what is required for most people's definition of being fit. Many people that are very fit risk their health. If you think otherwise, try to rationalize how getting knee, hip, or shoulder surgery from overuse is healthy.

  20. #20
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    I want to be reasonably fit and also healthy. I feel that I accomplish both of those things well. it just so happens that my genetics also tend to predispose me towards being somewhat skinny. side effects of long term steroid use notwithstanding.

    this is a big reason I ride a bike and only run relatively short distances. long distance running is painful. short distance running not so much. and for me, definitely not biking. being active makes me happy, and my healthy lifestyle helped me kick cancer to the curb. so don't presume to lecture me about healthy vs skinny because my goals are not unreasonable.

    I don't care much about the number I hit with my body fat percent as an absolute. what I care about is the visceral fat on my body. THAT is unhealthy. that is the fat I tended to pack on while on steroids and it is the fat that is most difficult to lose. so while I work on the visceral fat, I lose other fat, too. I'll worry about that later. I shouldn't have a problem considering how much I enjoy pizza, beer, cheeseburgers, and burritos.

  21. #21
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    Poor, misunderstood BMI. It's probably the single most misused fitness metric there is (though age-based heart rate formulas are a close second). BMI was originally meant to estimate trends in large populations, it was never intended to be applied to an individual. For example, a professional athlete could have so much lean muscle mass that they would fall into the obese category when they clearly are not. OTOH, 30-40% of Americans are obese, but it just takes a quick glance around to see it isn't because they are as ripped as a pro athlete.

    So no, as an individual you should look to other measurements and pretty much ignore BMI.
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  22. #22
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    BMI is driven by weight more than height. As such, heavy people have high BMI. BMI as a single metric has also led to what is known as the "skinny obese"--basically no muscle and high percentage of fat that yields a normal BMI. This is a much higher risk group than the fit heavy group. There isn't a perfect single measure, though. I say that because I don't like my BMI and could benefit from losing weight--yet, I'm reasonably fit.

  23. #23
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    I agree - BMI is completely useless to the individual. However the wellness program at my work seems to think it's one of the most important yardsticks of health. If you are in BMI category X, you are not healthy and need to do Y.

    It's just one more example of how information designed for public consumption is dumbed down to the point that it is meaningless.

    Being truly skinny may be overrated, but the average American is not in danger of that, and most of us could benefit from dropping excess body fat.

  24. #24
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    I'm almost two inches taller than the OP and weigh 160 lbs. (189 cm / 73 kg) My waist is 31.5" and chest 39". I'm 30 years of age and just ran 1.44 miles in the 12 minute Cooper's running test. I consider myself healthy and fit.

    I don't care too much about BMI (the results are off the further you're from the average height and if your body composition differs from the norm), but 170 lbs is certainly not an unhealthy weight for you.

  25. #25
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    Quote Originally Posted by Poe4soul View Post
    Being skinny is overrated. There is a lot of evidence that being a bit overweight is better than being underweight.

    People mix up being healthy with being fit. Some of the healthiest people are not fit and some of the fittest people are not healthy. Not that they are mutually exclusive but one has to keep it in mind when developing goals. The physical level for being healthy is far below what is required for most people's definition of being fit. Many people that are very fit risk their health. If you think otherwise, try to rationalize how getting knee, hip, or shoulder surgery from overuse is healthy.
    Think there's a clearer line and more correlation between being healthy and being fit than there is with this post. I mean I can't tell if I've been baffled with bs or dazzled with brilliance. Or what it has to do with Nate's post, or even the OP's query for that matter.
    Whatever, carry on.
    Round and round we go

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