'Ideal' BMI

Kelbelle30

Don't you just hate it? I was over the moon to hit my BMI healthy - suddenly those glorious numbers 23.9 appeared in front of me!

Then I hit 22.5! Brilliant!


Then, I did a silly quiz online to see how healthy I was - I'm quite proud of the massive health changes I have made in my life and thought I'd get a pat on the back from the quiz!

But no - the quiz said while I'm in the healthy range - the *ideal* BMI is 19-21!

All of a sudden my hard work seemed undermined!

hannah_ryann

I honestly hate the idea of BMI. It doesn't take into account muscle or frame build at ALL. When I reach my goal weight (5 foot 3, 140 lbs) My BMI will be 24.8. That's in the "normal" range. However, at 145, my BMI goes up to the "overweight" range. It's ridiculous, IMHO. At 115, my BMI is in the normal range, but when I weighed that, I looked very sick ( I actually had an eating disorder at that weight, so there ya go).

BMI is one tool you can use to gauge your health, but it by no means paints the entire picture. Take that number with a grain of salt, and CONGRATS on your health and weight loss journey so far!!

MinimalistShoeAddict

I have several problems with BMI. While I prefer to track body fat percentage, BMI is useful because it is easy to accurately calculate with this formula:

English BMI Formula
BMI = ( Weight in Pounds / ( Height in inches x Height in inches ) ) x 703

Metric BMI Formula
BMI = ( Weight in Kilograms / ( Height in Meters x Height in Meters ) )

Many people will point out that BMI has limitations when applied to children (when weight percentiles for age/height/sex are more relevant) and tall populations.

"For a given height, BMI is proportional to weight. However, for a given weight, BMI is inversely proportional to the square of the height. So, if all body dimensions double, and weight scales naturally with the cube of the height, then BMI doubles instead of remaining the same. So, taller people will have a BMI that is too high compared with their actual body fat levels.
BMI is used to assess how much a person’s body weight departs from what is desirable for a person of his or her height. However, BMI categories do not take into account many factors such as frame size and muscularity. Because BMI is dependent only on weight and height, it may overestimate adiposity in those with more lean body mass (eg, athletes) and underestimate adiposity in those with less lean body mass (eg, the elderly)."

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2912631/

The main problem with BMI is that for most adult non athlete populations it UNDERESTIMATES obesity for most (modern day Western) populations.

"BMI-defined obesity (≥ 30 kg/m2) was present in 21% of men and 31% of women, while BF %-defined obesity was present in 50% and 62%, respectively"

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2877506/

This is not a flaw in the BMI calculation itself, just merely a reflection that the world is far more overweight today than it was in the 1800s when the BMI formula was invented by Adolphe Quetelet. BMI generally overestimates fat tissue on those with more lean body mass (e.g., athletes) and underestimates excess fat tissue on those with less lean body mass

For these reasons BMI was explicitly cited by Ancel Keys as being appropriate for population studies, and inappropriate for individual diagnosis. However for most Americans, using body fat % to measure obesity rates will result in higher not lower obesity levels.

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Body_mass_index.html

The moral here is that while BMI is easy to calculate, individuals would be better off tracking body fat percentage as it is much more meaningful. Athletes, children, the elderly and those who are very tall should pay even less attention to BMI.

Ejourneys

I recommend investing about 20 bucks in body fat calipers and then going by this:


Source: AccuMeasure

Body fat percentage is a much better indicator than BMI. Also, one's age makes a difference.

neandermagnon

Don't you just hate it? I was over the moon to hit my BMI healthy - suddenly those glorious numbers 23.9 appeared in front of me!

Then I hit 22.5! Brilliant!


Then, I did a silly quiz online to see how healthy I was - I'm quite proud of the massive health changes I have made in my life and thought I'd get a pat on the back from the quiz!

But no - the quiz said while I'm in the healthy range - the *ideal* BMI is 19-21!

All of a sudden my hard work seemed undermined!

Ignore it. The ideal BMI is *not* 19-21!!! the ideal BMI for individuals depends on their frame size, i.e. there is no one size fits all ideal BMI. 19-21 BMI is maybe ideal for people with small frames (which refers to bone structure, i.e. width of shoulders, pelvis, rib cage etc). Larger framed people will be in the higher end of the BMI range at a healthy body fat percentage. Lots of athletes due to having greater muscle mass have a higher BMI, some falling into the overweight or obese range while being extremely fit, lean and healthy.

Body fat percentage is what counts. Carrying too much body fat is what causes the health risk. Having wider shoulders and pelvis than average for your height doesn't increase your health risk, but it will increase your BMI. Having more muscle mass actually improves your health, it certainly doesn't put you at risk, but it will increase your BMI. Having denser bones will improve your health, it's not a risk at all, but it will increase your BMI. Having a proportionally longer torso and shorter legs than average for your height won't increase your health risk, but it will increase your BMI. So I second the advice from the above poster re measuring body fat percentage instead. The healthy range for women is 18-28%, and within that range, if you want more muscle definition and a more "toned" look, aim for the lower end of that range, or if you want a "softer" more "curvy" look then aim for the higher end of that range. Within the healthy BF% range, it's about personal choice and aesthetics. Over 35% body fat for women is obese (the bf% ranges for men are different).

Another thing, one piece of advice I heard a while back which is really good, is to try to be as heavy as you can at an ideal dress size with a healthy body fat percentage, rather than trying to be as light as possible. this is because healthy bones and muscles are denser than weak, wasted bones and muscles, and so long as you're not actually carrying too much body fat it's actually healthier to be heavier. I'd argue with those saying that 19-21BMI is ideal, that this BMI actually would be underweight for a lot of people and would involve loss of bone density and muscle mass to achieve (which is not remotely healthy). For small framed people that BMI is healthy (and for very small framed people, maybe even lower than that would still be healthy), but really there's no one size fits all here. Body fat percentage is a better indicator, because frame size is hard to determine, but if you're at a healthy body fat percentage, then let your body be the weight it wants to be when you're fit, strong and healthy.

Doctorpurple

I started out with a BMI fo 22 before deciding to lose weight. I look ok at 22 still flat tummy but pretty large arms and thighs. I decided I want to have a BMI of 19. I currently have a BMI of around 19.6 and I'm quite happy with what I look like. I can wear a bikini with confidence even after meals. My goal is still at 19. So I'm planning to lose 3-4 more lbs before maintaince. Honestly I have to readjust my goals several times. I initially wanted 21, then 20, then 19. But I will not go lower than 19. There was a chart in the internet showing level of happiness amongst women (medium size sample size) and BMI and the happiest are the bmi of 19 and goes down in both directions as you progress. Maybe that's why those websites always suggest a BMI on the lower end of healthy. Honestly, I am quite petite 5'4.5'' and medium frame so I can pull 19 without looking too thin. I know a lot of people who are taller or have a larger or more muscular body would look too thin at that weight. I would say continue being proud of your achievements and adjust your goal in accordance with your liking and ignore those "ideal BMI" charts.