How do we judge a healthy weight range? BMI is no longer valid?

gt5841b

I want to understand how to judge a healthy weight range for myself in order to take opinion out of the equation. What is the standard we are using now? I feel like BMI calculations are dated right? Is body fat percentage the best metric? What is the best measurement tool?

Need2Exerc1se

If you are female, BMI is good. Body fat % is good and probably the best for both men and women, but it's expensive to get an accurate measurement.

lemurcat12

BMI is accurate for most women. It's typically accurate even for men unless they have above average muscle mass (same for women, but you need to be more out of the average), and people in that situation tend to know it. BF% is a better measure, but most people don't know theirs -- you have to be able to look at yourself accurately (many people can do this better with photos) to estimate or use one of the more accurate tests like DEXA.

That said, there's a wide range that is healthy and no need to know exact BF% to know if you are there. When I was still a bit above the BMI range (like 26, and I am not an outlier), my doctor said based on overall fitness (I was really active) and tests it wasn't something to worry about. I told her that was great but I wanted to be thinner anyway, and lost more weight, in part for vanity reasons or just because I feel better around 21-22 BMI. If I'd been maintaining forever at 26 and was otherwise happy with my looks and how I felt and my test results and my activity level and ability to perform as desired, I probably wouldn't worry about it.

Need2Exerc1se

I'd also recommend waist to height measurement as a good indicator.

ninerbuff

Getting an idea of what your lean body mass is (even if it's off by say 3%), you can get an ideal body weight if you know it and use this formula.

Your lean body mass divided by (1 minus the body fat percentage you want to be)

So say you're 120lbs lean body mass and want to be 20% body fat. Then apply the formula.

120/(1-.20)
120/.80= 150lbs

So 150lbs would be the target weight (approximate) to be at 20% body fat.

A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition

Dove0804

BMI is a good guideline for most people, and is not dated. It does not apply as well to the very old (due to muscle wasting) and serious body-builders. We use it often in the hospital to guide dose-adjusting of various medications (along with ideal body weight). It works great as a generalization.

The thing to keep in mind: it is a guideline, and BMI gives a very generous range regarding what is considered a healthy weight. (My healthy weight range is defined as between 111-149 lbs- that's almost 40 lbs of wiggle room!) The problem is, there's been a movement of people in overweight nations that are unhappy with the healthy weight ranges given and have been trying to denounce the whole thing as bogus.

In many countries like the U.S., overweight has become the norm, so many people have lost perspective of what a healthy weight actually looks like. Many people will swear up and down that they are pure muscle and are an outlier, when they actually do have quite a bit of excess fat they could lose. That's not to say they look bad, or should lose it- if someone's happy at a certain weight I say stick with what makes you feel your best. Usually people trying to get rid of the BMI scale is people who fall into the overweight or obese range and are not happy about the label.

Body fat percentage, when done accurately, is probably the best indication though. It's just harder to do. I personally use a combination of everything to get an idea of where I fall.

I'm still obese by every measure, but I'm getting there!

ForecasterJason

On the flip side, there are some people for whom the healthy weight range may extend just below the underweight/normal weight cutoff, depending on body composition.

Traveler120

Usually, it's said to be inaccurate for those who're VERY muscular. The average woman is nowhere near as muscular as Serena Williams and she's 5'9" and said to be 155 lbs, BMI 22.89. She'd have to be 170 lbs to reach overweight BMI of 25+ and in her case, it would not apply coz she's so muscular. So, unless you're as muscular as she is, then yeah, BMI is a good indicator of what's a healthy weight.

I think fat acceptance and the obesity epidemic is distorting people's view of what's truly normal weight so folks start blaming the BMI indicator for being wrong, when in reality, people are just too fat.

MarkusDarwath

BMI has never been valid, or more specifically, the scales given defining "ideal" and "overweight" are nonsense, based more on someone's aesthetic sense of what a person should look like and not so much on actual health risk factors. The truth of the matter is there is no statistically significant increase in health risk markers for someone who falls in the "overweight" BMI range so long as they are not gaining weight and pushing toward "obese". For at least half the population, even the high end of their "ideal" range is overly skinny without offering any health benefit. I suspect the category designations were established by vegans.

Body fat percentage is a far superior metric. BMI is just a poor attempt at estimating BFP.

To address a couple points from another poster... yes, I am obese, and I make no bones about that. The last time I fit in the supposedly "healthy" BMI range was in high school, and at that time (before BMI was even a 'thing' in the general public) I was lifting weights because I was too damn skinny. BMI completely fails to account for factors such as age and (more importantly) frame size. According to BMI charts, 185 pounds is the most I should weigh without being "overweight". I can say that being 6'1", 46 yo, and large framed there is absolutely no reason I should weigh less than 210-220. Heck, at 262 pounds and 34-35% body fat, my present -lean mass- is around 170 pounds. I would literally have to lose significant amounts of muscle in order to fit the "ideal" BMI weight range at a healthy (not a competitive body builder) body fat percentage. And no, I do not think I am a heavily muscled outlier at less than 30% muscle mass... I'm just big... and while I'm working toward no longer being fat, I have no desire to cease being big.

Dove0804

MarkusDarwath wrote: »

BMI has never been valid, or more specifically, the scales given defining "ideal" and "overweight" are nonsense, based more on someone's aesthetic sense of what a person should look like and not so much on actual health risk factors. The truth of the matter is there is no statistically significant increase in health risk markers for someone who falls in the "overweight" BMI range so long as they are not gaining weight and pushing toward "obese". For at least half the population, even the high end of their "ideal" range is overly skinny without offering any health benefit. I suspect the category designations were established by vegans.

Body fat percentage is a far superior metric. BMI is just a poor attempt at estimating BFP.

To address a couple points from another poster... yes, I am obese, and I make no bones about that. The last time I fit in the supposedly "healthy" BMI range was in high school, and at that time (before BMI was even a 'thing' in the general public) I was lifting weights because I was too damn skinny. BMI completely fails to account for factors such as age and (more importantly) frame size. According to BMI charts, 185 pounds is the most I should weigh without being "overweight". I can say that being 6'1", 46 yo, and large framed there is absolutely no reason I should weigh less than 210-220. Heck, at 262 pounds and 34-35% body fat, my present -lean mass- is around 170 pounds. I would literally have to lose significant amounts of muscle in order to fit the "ideal" BMI weight range at a healthy (not a competitive body builder) body fat percentage. And no, I do not think I am a heavily muscled outlier at less than 30% muscle mass... I'm just big... and while I'm working toward no longer being fat, I have no desire to cease being big.

I'm not sure where you got most of this information, especially that which I bolded. I think a lot of what you said in your post is a prime example of people in the U.S. (or other overweight nation) having a skewed idea of what a healthy weight is because we are surrounded by overweight/obese people. We consider people in the normal range as being underweight or skinny. That is our perception given the norm of today's society. If you were to travel back in time 60 years or earlier, or visit a country with very few overweight/obese people (i.e. most east asian countries), I think it might change how you perceive weight. There are a lot of people who believe they are naturally big-boned or just big- but they really aren't.

There are numerous, numerous health risks that increase as visceral fat increases, and you don't have to fall in the "obese" range for that risk to be increased. No, being overweight is not as bad as being obese health-wise, but having extra, unnecessary fat doesn't do anybody any favors.

If you are happier being big, that's fine- but don't denounce the BMI scale as being completely bogus because you prefer being that way. You have a higher lean muscle mass because you have more weight to carry- yes you would lose muscle as you lose weight, because you wouldn't need it. If you were serious about keeping lean muscle mass along weight weight loss, you'd have to do some serious lifting, and then you might end up closer to that of a body-builder with a low body fat percentage. Muscle loss is a fact of weight loss, and it doesn't necessarily mean it's a bad thing. Can you imagine if I, a woman, had the same lean muscle mass at 189 lbs as I did at 260 lbs? That's ridiculous. My body needed more muscle to carry around that weight. That's why most people find it difficult or impossible to carry around, say, 100 lbs of something heavy even though they used to be 100 lbs heavier and carry that around every day.

I do agree, and did state, that body fat percentage is a much better indicator. Using your number of <30%- that in no way would be an outlier. An unhealthy BF percentage is often defined, for men, as being above 25%. Average, 18-24%, physically fit as 14-17% and athletes being less than that. I HIGHLY doubt you'd be in danger of being too skinny if you were to be under 185 lbs. I don't believe that for a second. Maybe by your perceptions, but not from a health standpoint.
BMI shouldn't be used for kids, including high school kids. I was referring to adults when I was talking about BMI.

middlehaitch

My SO at 6'3 and 235lbs swore that the BMI just didn't work for him. He was too tall.
After watching me count calories and lose weight for a year he decided to give it a go. Guess what, he lost 40lbs, sits at the top of a normal BMI quite happily, and can't believe he thought he was an exception.

Me, at 5'1, could easily fit into @ForecasterJason's just below a normal BMI.
I maintain a range of 100-105 just because it is healthier for me, but quite often start to drop to 98, the very bottom of normal, and if I didn't bump my calories I would easily and happily be below.

I think BMI is a good indicator for all but the very muscular.

Cheers, h.

(Just in case you worry- don't have an eating disorder, eat about 1450 a day and have been maintaining for 6+ years)

amusedmonkey

BMI is a good general indicator. Slightly under or slightly over the normal range is fine. Is your weight within the normal BMI range or close to it? Is your natural waist circumference 80 cm (~31.5 inches) or under? Are you pleased with the way you look?

If the answer is yes to the above, you are safely within a good range. Are your general health markers within a good range (blood sugar, cholesterol..etc)? If they are not, you may find being at the lower end of BMI more beneficial.

BMI is not invalid, it's just more valid for some than others. Normal weight is defined as a range not a number for a reason, to accommodate some of that variance among people. Some are still outliers, but not as many as you think and not as many women. For those who are, being at 27 or 17 BMI, for example, and healthy otherwise is a nonissue.

robininfl

BMI is more likely to be wrong in the other direction (it's more common to be overfat without being technically overweight, than to be overweight without being overfat)

Bodyfat % would be a great way to measure fatness.

For most body types, waist to height is good.

Fitness, how far can you run without getting tired, how much can you lift?

Blood pressure, blood sugar, blood fats.

3dogsrunning

BMI is not "wrong". It is meant to be an indicator, not diagnostic. If you fall outside of the healthy range, then other methods are used to determine if one is overweight or not. It is a reasonable indicator for the majority of people. And there is a strong correlation between BMI and various metabolic disorders and diseases.

The CDC says
"BMI is a person's weight in kilograms divided by the square of height in meters. BMI does not measure body fat directly, but research has shown that BMI is moderately correlated with more direct measures of body fat obtained from skinfold thickness measurements, bioelectrical impedance, densitometry (underwater weighing), dual energy x-ray absorptiometry (DXA) and other methods 1,2,3. Furthermore, BMI appears to be as strongly correlated with various metabolic and disease outcome as are these more direct measures of body fatness 4,5,6,7,8,9. In general, BMI is an inexpensive and easy-to-perform method of screening for weight category, for example underweight, normal or healthy weight, overweight, and obesity."

The_Enginerd

Like the others have said, BMI is accurate for most people, but people's perception of what a normal "healthy" weight is out of whack when the majority of people in the US are overweight or obese. Despite being the same weight I was back in college, I'm considered a lot thinner than I was back then (15 years ago) because everyone else got heavier.

Hornsby

MarkusDarwath wrote: »

BMI has never been valid, or more specifically, the scales given defining "ideal" and "overweight" are nonsense, based more on someone's aesthetic sense of what a person should look like and not so much on actual health risk factors. The truth of the matter is there is no statistically significant increase in health risk markers for someone who falls in the "overweight" BMI range so long as they are not gaining weight and pushing toward "obese". For at least half the population, even the high end of their "ideal" range is overly skinny without offering any health benefit. I suspect the category designations were established by vegans.

Body fat percentage is a far superior metric. BMI is just a poor attempt at estimating BFP.

To address a couple points from another poster... yes, I am obese, and I make no bones about that. The last time I fit in the supposedly "healthy" BMI range was in high school, and at that time (before BMI was even a 'thing' in the general public) I was lifting weights because I was too damn skinny. BMI completely fails to account for factors such as age and (more importantly) frame size. According to BMI charts, 185 pounds is the most I should weigh without being "overweight". I can say that being 6'1", 46 yo, and large framed there is absolutely no reason I should weigh less than 210-220. Heck, at 262 pounds and 34-35% body fat, my present -lean mass- is around 170 pounds. I would literally have to lose significant amounts of muscle in order to fit the "ideal" BMI weight range at a healthy (not a competitive body builder) body fat percentage. And no, I do not think I am a heavily muscled outlier at less than 30% muscle mass... I'm just big... and while I'm working toward no longer being fat, I have no desire to cease being big.

I used to think just like you, then I surpassed my expectations.

ETA: at 6'1, you can be 189 without being overweight. Assuming you didn't lose any muscle mass on your way to 189, that would put you at 10%. A pretty ripped individual and still falls in the range of "Normal".

Traveler120

MarkusDarwath wrote: »

.... For at least half the population, even the high end of their "ideal" range is overly skinny ........

This is exactly the kind of distorted mindset that develops in a largely overweight/obese US.

For a 5'4" woman, 146 lbs, BMI 25, is the high end of normal wt range. You being overweight, or if we were in a room of overweight/obese pple, would view that as "overly skinny". I was 151 lbs with lots of belly fat (the unhealthiest kind of fat) and now I'm down to a good looking and normal 116 lbs with a BMI of 20 which you would probably view as "anorexic/deathly skinny" because you've lost sight of reality.

robininfl

The_Enginerd wrote: »

Like the others have said, BMI is accurate for most people, but people's perception of what a normal "healthy" weight is out of whack when the majority of people in the US are overweight or obese. Despite being the same weight I was back in college, I'm considered a lot thinner than I was back then (15 years ago) because everyone else got heavier.

Yes. I have stayed in the same weight range but it's farther from the average now than when I was younger.

BMI tables are built from average health risk tables for increasing weight. They aren't some conspiracy, it's been found that having body mass lower or higher than the range in there increases risk for a the population of people. That's all. It's a range to accomodate a variety of body types and men and women. I could not weigh the top of the BMI healthy range and be healthy, someone else can't be right at the bottom of it and be healthy. There are statistical outliers in each direction, but so many people seem to think they are outliers at the top, that's really unlikely.

cwolfman13

BMI is just fine for the vast majority of the population. You have to understand what the range is for though...BMI is a range, not so that you can pick and choose within the range, but to accommodate a variety of body types, etc. Someone with a broader, more athletic build for example would not do well trying to get to the low end of BMI that would be for a very petite individual.

BF% in combination with BMI is a good way to go.

sculli123

For a sedentary person, BMI is OK. For an athlete, it's not really so good. BF% is better, hard to be accurate as already noted but still better than BMI. Then again, the mirror is good enough for me. lol

MarkusDarwath

Dove0804 wrote: »

I'm not sure where you got most of this information, especially that which I bolded. I think a lot of what you said in your post is a prime example of people in the U.S. (or other overweight nation) having a skewed idea of what a healthy weight is because we are surrounded by overweight/obese people.

There are quite a few studies demonstrating that those who are mildly "overweight" according to BMI have a lower risk of sudden mortality than those in the "ideal" range. These are very broad studies and any number of factors come into play, such as greater mass provides better protection from injury in accidents, and allows more leeway in unexpected rapid weight loss due to illness.

There are numerous, numerous health risks that increase as visceral fat increases, and you don't have to fall in the "obese" range for that risk to be increased. No, being overweight is not as bad as being obese health-wise, but having extra, unnecessary fat doesn't do anybody any favors.

And BMI is not visceral fat. It is a height to weight ratio with no specification as to composition. Also, subcutaneous fat does not carry the same risks for small to moderate increases as visceral fat does. In other words, risk is properly evaluated on a case-by-case basis. Again, the broad studies strictly comparing BMI numbers with health outcomes show no -statistically significant- correlation between having an "overweight" BMI number and the development of health problems... with a caveat that those who are on the higher end of "overweight" and on a trend of weight gain do run counter to the evidence shown by the rest of the group.

If you are happier being big, that's fine- but don't denounce the BMI scale as being completely bogus because you prefer being that way.

I denounce the scale as bogus because BMI does not actually measure anything of value, and the ranges assigned to "ideal" and "overweight" do not have an accurately positive correspondence to overall health.

You have a higher lean muscle mass because you have more weight to carry- yes you would lose muscle as you lose weight, because you wouldn't need it.

Sorry, I still need it. I'm not a marathon runner or endurance cyclist, nor am I sedentary. My work often requires lifting heavy objects, and so my muscle needs to do quite a bit more than carrying my own mass. It is not a simple one-to-one trade that if I lose 20 pounds of muscle, I can lift and carry something 20 pounds heavier.

If you were serious about keeping lean muscle mass along weight weight loss, you'd have to do some serious lifting, and then you might end up closer to that of a body-builder with a low body fat percentage. Muscle loss is a fact of weight loss, and it doesn't necessarily mean it's a bad thing. Can you imagine if I, a woman, had the same lean muscle mass at 189 lbs as I did at 260 lbs? That's ridiculous. My body needed more muscle to carry around that weight. That's why most people find it difficult or impossible to carry around, say, 100 lbs of something heavy even though they used to be 100 lbs heavier and carry that around every day.

Again, this is a matter of weight distribution and the way the muscles and skeleton work together. A 189 pound woman at 20% body fat and the same muscle mass is going to look gorgeous compared to the 260 pound woman at 40% body fat.

I do agree, and did state, that body fat percentage is a much better indicator. Using your number of <30%- that in no way would be an outlier. An unhealthy BF percentage is often defined, for men, as being above 25%. Average, 18-24%, physically fit as 14-17% and athletes being less than that. I HIGHLY doubt you'd be in danger of being too skinny if you were to be under 185 lbs. I don't believe that for a second. Maybe by your perceptions, but not from a health standpoint.

Again, BMI is not body fat percentage. BMI is meant to be an approximation of BFP, but it's not usefully accurate for a lot of people and does not distinguish between lean mass (good), visceral fat (bad if too much), subcutaneous fat (less bad if too much) or even water weight. One should never look at the BMI charts to determine their ideal weight, they should look at body fat percentage and their personal appearance and performance goals.

If I dropped from my current weight to 185 and maintained my present lean mass I would be at 8% body fat. Yes, I expect there will be some muscle loss as I continue to lose weight, but there is no reason I should, or at all want, to lose 20 pounds worth of muscle. There is no health benefit to shedding muscle mass. Yet the BMI charts insist that I would be healthier at a weight that would -require- me to drop 20 pounds of muscle in addition to 55 pounds of fat. (and that's if I settled for 20% body fat instead of 15%),
Not to mention I would look scrawny and frail.

On the other end of the spectrum, I also know someone, a petite runner, who comes out as "underweight" on BMI charts, but does -not- look underweight.
As an estimator of body fat, BMI is most accurate for medium framed, sedentary people. And while that may be the average, there is a large difference between average and mean. BMI is not worthwhile for most individuals.
Perhaps not coincidentally, it was never developed for individual assessment to begin with. It was an equalization tool to study trends in large populations.