BMI

Philtex

What are your thoughts on BMI? I just calculated my current BMI and what weight I need to get to for a "healthy" BMI. The top of the healthy range is one pound lower than the goal I had set for myself. I can adjust one pound. I see BMI as one more tool in the toolbox, not some end-all, be-all. Your thoughts?

Flintwinch

BMI is a measure to compare healthy weight, overweight and obese conditions in Populations. Doctors and dietitians may also use this as a guide but for Individuals, it can be faulty. Your healthiest weight is that at which you feel and observe optimal physical fitness and have normal blood tests and other measures of health.

I get DEXA body composition scans done relatively cheap at $50 per scan through BodySpec. It measures the percentage of bone, fat and lean muscle tissue. My interest in all this started 5 years ago when I found out I had a high heart arteries plaque level. I've been following the American Heart Associations "Essential Eight healthy heart guidelines since. I've lost fat, but as importantly I've gained muscle. My blood tests are normal, but my BMI is 28. Geriatric dietitians recommend a higher weight (BMI) for the elderly (I'm 75) and studies show that a higher weight is beneficial in case of illness, and does not lead to decreased longevity.

Using the green/yellow/red light model, I consider my current weight to be yellow, which is ok with me as long as everything else measures ok. Perfect can be the enemy of the good. For purposes of full disclosure, my cardiologist gives me the green light.

crewahl

Good to see @Flintwinch! 👍🏻

I’ll go him one better on the Rant-o-Meter - BMI is a bogus metric when applied to an individual. It was developed in the 19th century by a statistician to measure mortality risk in a population based on obesity. Like any measure of a population, it becomes less and less valuable and accurate as you try to take it down to an increasingly granular level such as the individual. It doesn’t consider age or gender, and the good lord knows there are differences in body composition between genders.

I suspect that for most men beyond their teens, it can be tough to get down to the top of their BMI range. Other than one fleeting week last year, I haven’t been there since college. The reality is that to live at that level would require a degree of activity and dietary restriction that I simply can’t or won’t do. Based on my doctor's advice, I’m at a healthy weight if I’m not more than eleven pounds over the top of my BMI range.

Rant out.

You may want to google “smart BMI”, which provides a calculation that considers age and gender. While traditional BMI has me overweight, Smart BMI has me in the middle of their green zone.

You might also want to google a Danish study on the relationship between age, weight, and mortality risk. Short version is that there’s a relationship, and it’s a U-shaped curve. In other words, your risk goes up if your underweight just as it goes up if you’re overweight. The curve retains its shape, but it shifts up and to the right as you age. It’s a pretty interesting read.

Flintwinch

@crewahl--You hit the nail on the head with surgical precision. Other than at a population level, BMI misses the mark by a wide margin. I did use the SmartBMI calculator that you mentioned. It puts me at the upper edge of green. As far as I'm concerned, my weight is ok where it is and any efforts to reduce it below 25 causes unnecessary stress. While I follow the basics of a Mediterranean Diet, I am flexible in eating so long as I stay within an acceptable weight range. My focus nowadays, in addition to diet, are stress management, exercise and sleep (One of the best parts of the Mediterranean Diet is the afternoon nap). And I'm still able to get on my bike and go for a long ride, something that as a youth, or even a middle-ager, I would not have thought possible. Life is good.

steve0mania

I think BMI is an incredibly simple objective measure of "proportions" that for most of us is actually as good a target as any. If one is super-muscular, then BMI probably isn't very useful, but again, for most "mortal men (and women)" it's good-enough.

With all due respect, good blood tests are not a measure of health, but rather a measure of lack of significant disease. While it's nice to have good blood tests, and cholesterol measures have some real predictive power, I don't think they're as useful a measure as folks would like. HgbA1c is probably useful for many folks who are significantly overweight and are drifting into the world of type II diabetes, having a normal A1c doesn't mean that one is perfectly healthy.

With all of that said, if you don't want to hold by BMI, I think that's fine, but be clear about the rationale. For many, trying to get below a BMI of 25 is simply too stressful, and for overall health, it's better to be 200 lbs than 300 lbs, even if you're not going to get to 150 or 175 (or whatever would put you in the "normal" weight category).

Yes, there are better measures than BMI. Ultimately, your goal weight should be one that makes sense to you in all facets of your life, including ability to maintain, how you look, how you feel, if you are able to do all of the physical activities you want, etc. In my case, my stomach is too big when I'm at the top of my BMI range (i.e., with a BMI of 25), and I find that I look and feel best when I'm closer to a BMI of 23 or even 22.5.

Flintwinch

@steve0mania "Yes, there are better measures than BMI." And we should be using better measures. In the realm of heart or brain attack risk, we use many factors to predict an individual's risk. It is the whole pattern, rather than any single risk factor that is meaningful. BMI in itself is meaningless for an individual and even distracts physicians from seeing the whole picture.

88olds

When I started WW, that was what I aimed at. I’m at the top of the healthy range. But I’m fat around the middle. So BMI is something but not everything.

Flintwinch

BMI fails to differentiate between muscle mass and fat. These two elements have vastly different health impacts. For example, muscle mass is associated with positive health outcomes, while excess fat is linked to a higher risk of metabolic disease and cancer.