When BMI Doesn’t Measure Up
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When BMI Doesn’t Quite Measure Up
Last month, we did a “Friday Mythbusters” edition of 10almonds, tackling many of the misconceptions surrounding obesity. Amongst them, we took a brief look at the usefulness (or lack thereof) of the Body Mass Index (BMI) scale of weight-related health for individuals. By popular subscriber request, we’re now going to dive a little deeper into that today!
The wrong tool for the job
BMI was developed as a tool to look at large-scale demographic trends, stemming from a population study of white European men, who were for the purpose of the study (the widescale health of the working class in that geographic area in that era), considered a reasonable default demographic.
In other words: as a system, it’s now being used in a way it was never made for, and the results of that misappropriation of an epidemiological tool for individual health are predictably unhelpful.
If you want to know yours…
Here’s the magic formula for calculating your BMI:
- Metric: divide your weight in kilograms by your height in square meters
- Imperial: divide your weight in pounds by your height in square inches and then multiply by 703
“What if my height doesn’t come in square meters or square inches, because it’s a height, not an area?”
We know. Take your height and square it anyway. If this seems convoluted and arbitrary, yes, it is.
But!
While on the one hand it’s convoluted and arbitrary… On the other hand, it’s also a gross oversimplification. So, yay for the worst of both worlds?
If you don’t want to grab a calculator, here’s a quick online tool to calculate it for you.
So, how did you score?
According to the CDC, a BMI score…
- Under 18.5 is underweight
- 18.5 to 24.9 is normal
- 25 to 29.9 is overweight
- 30 and over is obese
And, if we’re looking at a representative sample of the population, where the representation is average white European men of working age, that’s not a bad general rule of thumb.
For the rest of us, not so representative
BMI is a great and accurate tool as a rule of thumb, except for…
Women
An easily forgotten demographic, due to being a mere 51% of the world’s population, women generally have a higher percentage of body fat than men, and this throws out BMI’s usefulness.
If pregnant or nursing
A much higher body weight and body fat percentage—note that these are two things, not one. Some of the extra weight will be fat to nourish the baby; some will be water weight, and if pregnant, some will be the baby (or babies!). BMI neither knows nor cares about any of these things. And, this is a big deal, because BMI gets used by healthcare providers to judge health risks and guide medical advice.
People under the age of 16 or over the age of 65
Not only do people below and above those ages (respectively) tend to be shorter—which throws out the calculations and mean health risks may increase before the BMI qualifies as overweight—but also:
- BMI under 23 in people over the age of 65 is associated with a higher health risk
- A meta-analysis showed that a BMI of 27 was the best in terms of decreased mortality risk for the over-65 age group
This obviously flies in the face of conventional standards regards BMI—as you’ll recall from the BMI brackets we listed above.
Read the science: BMI and all-cause mortality in older adults: a meta-analysis
Athletic people
A demographic often described in scientific literature as “athletes”, but that can be misleading. When we say “athletes”, what comes to mind? Probably Olympians, or other professional sportspeople.
But also athletic, when it comes to body composition, are such people as fitness enthusiasts and manual laborers. Which makes for a lot more people affected by this!
Athletic people tend to have more lean muscle mass (muscle weighs more than fat), and heavier bones (can’t build strong muscles on weak bones, so the bones get stronger too, which means denser)… But that lean muscle mass can actually increase metabolism and help ward off many of the very same things that BMI is used as a risk indicator for (e.g. heart disease, and diabetes). So people in this category will actually be at lower risk, while (by BMI) getting told they are at higher risk.
If not white
Physical characteristics of race can vary by more than skin color, relevant considerations in this case include, for example:
- Black people, on average, not only have more lean muscle mass and less fat than white people, but also, have completely different risk factors for diseases such as diabetes.
- Asian people, on average, are shorter than white people, and as such may see increased health risks before BMI qualifies as overweight.
- Hispanic people, on average, again have different physical characteristics that throw out the results, in a manner that would need lower cutoffs to be even as “useful” as it is for white people.
Further reading on this: BMI and the BIPOC Community
In summary:
If you’re an average white European working-age man, BMI can sometimes be a useful general guide. If however you fall into one or more of the above categories, it is likely to be inaccurate at best, if not outright telling the opposite of the truth.
What’s more useful, then?
For heart disease risk and diabetes risk both, waist circumference is a much more universally reliable indicator. And since those two things tend to affect a lot of other health risks, it becomes an excellent starting point for being aware of many aspects of health.
Pregnancy will still throw off waist circumference a little (measure below the bump, not around it!), but it will nevertheless be more helpful than BMI even then, as it becomes necessary to just increase the numbers a little, according to gestational month and any confounding factors e.g. twins, triplets, etc. Ask your obstetrician about this, as it’s beyond the scope of today’s newsletter!
As to what’s considered a risk:
- Waist circumference of more than 35 inches for women
- Waist circumference of more than 40 inches for men
These numbers are considered applicable across demographics of age, sex, ethnicity, and lifestyle.
There are more options than just waist circumference though; we delve into them in detail here:
Take care!
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How does the drug abemaciclib treat breast cancer?
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The anti-cancer drug abemaciclib (also known as Vernezio) has this month been added to the Australian Pharmaceutical Benefits Scheme (PBS) to treat certain types of breast cancer.
This significantly reduces the cost of the drug. A patient can now expect to pay A$31.60 for a 28-day supply ($7.70 with a health care concession card). The price of abemaciclib without government subsidy is $4,250.
So what is abemaciclib, and how did we get to this point?
It stops cells dividing
Researchers at the pharmaceutical company Eli Lilly developed abemaciclib and published the first study on the drug (then known as LY2835219) in 2014.
Abemaciclib is a type of drug known as a “cyclin-dependent kinase inhibitor”. It’s taken as a pill twice a day.
To maintain our health, many of the cells in our bodies need to grow and divide to produce new cells. Cancers develop when cells grow and divide out of control. Therefore, stopping cells from dividing into new cells is one way that cancer can be fought.
When cells divide, they have to make a copy of their DNA to pass onto the new cell. “Cyclin-dependent kinases” (CDKs for short) are essential for this process. So, if you stop the CDKs, you stop the DNA copying, you stop cells dividing, and you fight the cancer.
However, there are different types of CDKs, and not all cancers need them all to grow. Abemaciclib specifically targets CDK4 and CDK6. Thankfully, a lot of cancers do need these CDKs, including some breast cancers.
The drug targets CDK4 and CDK6. Photoroyalty/Shutterstock But abemaciclib will only be effective against cancers that rely on CDK4 and CDK6 for continued growth. This specificity also means abemaciclib is fairly unique, so it can’t easily be replaced with a different drug.
Two other CDK4/6 inhibitors were developed around the same time as abemaciclib, and are called ribociclib and palbociclib. Both of these drugs are also on the PBS for specific types of breast cancer. As the drugs differ in their chemical structures, they have slight differences in the way they are taken up and processed by the body. The preferred drug given to a breast cancer patient will depend on their unique circumstances.
What are the side effects?
Research is still ongoing into the differences between each of these CDK4/6 inhibitors, but it is known that the side effects are largely similar, but can differ in severity.
The most common side effects of abemaciclib are fatigue, diarrhoea and neutropenia (reduced white blood cells). The gastrointestinal issues are generally more severe with abemaciclib.
If these side effects are too severe, abemaciclib treatment can be stopped.
What types of cancer has abemaciclib been approved for?
In 2017, the United States Food and Drug Administration (FDA) approved abemaciclib for the treatment of patients with metastatic HR+/HER2- (hormone receptor-positive and human epidermal growth factor receptor 2-negative) breast cancer who did not respond to standard endocrine therapy.
Australia’s Therapeutic Goods Administration (TGA) similarly approved abemaciclib in 2022 as an “adjuvant” therapy (after the initial surgery to remove the tumour) for patients with HR+/HER2- invasive early breast cancer which had spread to lymph nodes and was at high risk of returning.
The drug is approved for people with early breast cancer which is at high risk of returning. PeopleImages.com – Yuri A/Shutterstock As of May 1 2024, the PBS covers this use of abemaciclib in combination with endocrine therapy such as fulvestrant, which is also listed on the PBS. Endocrine therapy, also known as hormonal therapy, blocks hormone receptor positive (HR+) cancers from receiving the hormones they need to survive.
Could abemaciclib be used for other cancers in the future?
Abemaciclib is of great interest to scientists and medical practitioners, and testing is ongoing to assess the effectiveness of abemaciclib in treating a range of other cancers, including gastrointestinal cancers and blood cancers.
Abemaciclib may even be usable in brain cancers, as it has long been known to be capable of crossing the blood-brain barrier, a common stumbling block for potential anti-cancer drugs.
Time will tell whether the role of abemaciclib in health care will be expanded. But for now, its inclusion on the PBS is sure to bring some relief to breast cancer patients nationwide.
Sarah Diepstraten, Senior Research Officer, Blood Cells and Blood Cancer Division, Walter and Eliza Hall Institute and John (Eddie) La Marca, Senior Resarch Officer, Walter and Eliza Hall Institute
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Hormones & Health, Beyond The Obvious
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Wholesome Health
This is Dr. Sara Gottfried, who some decades ago got her MD from Harvard and specialized as an OB/GYN at MIT. She’s since then spent the more recent part of her career educating people (mostly: women) about hormonal health, precision, functional, & integrative medicine, and the importance of lifestyle medicine in general.
What does she want us to know?
Beyond “bikini zone health”
Dr. Gottfried urges us to pay attention to our whole health, in context.
“Women’s health” is often thought of as what lies beneath a bikini, and if it’s not in those places, then we can basically treat a woman like a man.
And that’s often not actually true—because hormones affect every living cell in our body, and as a result, while prepubescent girls and postmenopausal women (specifically, those who are not on HRT) may share a few more similarities with boys and men of similar respective ages, for most people at most ages, men and women are by default quite different metabolically—which is what counts for a lot of diseases! And note, that difference is not just “faster” or “slower””, but is often very different in manner also.
That’s why, even in cases where incidence of disease is approximately similar in men and women when other factors are controlled for (age, lifestyle, medical history, etc), the disease course and response to treatment may vary considerable. For a strong example of this, see for example:
- The well-known: Heart Attack: His & Hers ← most people know these differences exist, but it’s always good to brush up on what they actually are
- The less-known: Statins: His & Hers ← most people don’t know these differences exist, and it pays to know, especially if you are a woman or care about one
Nor are brains exempt from his…
The female brain (kinda)
While the notion of an anatomically different brain for men and women has long since been thrown out as unscientific phrenology, and the idea of a genetically different brain is… Well, it’s an unreliable indicator, because technically the cells will have DNA and that DNA will usually (but not always; there are other options) have XX or XY chromosomes, which will usually (but again, not always) match apparent sex (in about 1/2000 cases there’s a mismatch, which is more common than, say, red hair; sometimes people find out about a chromosomal mismatch only later in life when getting a DNA test for some unrelated reason), and in any case, even for most of us, the chromosomal differences don’t count for much outside of antenatal development (telling the default genital materials which genitals to develop into, though this too can get diverted, per many intersex possibilities, which is also a lot more common than people think) or chromosome-specific conditions like colorblindness…
The notion of a hormonally different brain is, in contrast to all of the above, a reliable and easily verifiable thing.
See for example:
Alzheimer’s Sex Differences May Not Be What They Appear
Dr. Gottfried urges us to take the above seriously!
Because, if women get Alzheimer’s much more commonly than men, and the disease progresses much more quickly in women than men, but that’s based on postmenopausal women not on HRT, then that’s saying “Women, without women’s usual hormones, don’t do so well as men with men’s usual hormones”.
She does, by the way, advocate for bioidentical HRT for menopausal women, unless contraindicated for some important reason that your doctor/endocrinologist knows about. See also:
Menopausal HRT: A Tale Of Two Approaches (Bioidentical vs Animal)
The other very relevant hormone
…that Dr. Gottfried wants us to pay attention to is insulin.
Or rather, its scrubbing enzyme, the prosaically-named “insulin-degrading enzyme”, but it doesn’t only scrub insulin. It also scrubs amyloid beta—yes, the same that produces the amyloid beta plaques in the brain associated with Alzheimer’s. And, there’s only so much insulin-degrading enzyme to go around, and if it’s all busy breaking down excess insulin, there’s not enough left to do the other job too, and thus can’t break down amyloid beta.
In other words: to fight neurodegeneration, keep your blood sugars healthy.
This may actually work by multiple mechanisms besides the amyloid hypothesis, by the way:
The Surprising Link Between Type 2 Diabetes & Alzheimer’s
Want more from Dr. Gottfried?
You might like this interview with Dr. Gottfried by Dr. Benson at the IMCJ:
Integrative Medicine: A Clinician’s Journal | Conversations with Sara Gottfried, MD
…in which she discusses some of the things we talked about today, and also about her shift from a pharmaceutical-heavy approach to a predominantly lifestyle medicine approach.
Enjoy!
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Spark – by Dr. John Ratey
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We all know that exercise is good for mental health as well as physical. So, what’s so revolutionary about this “revolutionary new science of exercise and the brain”?
A lot of it has to do with the specific neuroscience of how exercise has not only a mood-boosting effect (endorphins) and neuroprotective effect (helping to guard against cognitive decline), but also promotes neuroplasticity… e.g., the creation and strengthening of neural pathways, as well as boosting the structure of the brain in some parts such as the cerebellum.
The book also covers not just “exercise has these benefits”, but also the “how this works” of all kinds of brain benefits, including:
- against Alzheimer’s
- mitigating ADHD
- managing menopause
- dealing with addiction
…and more. And once we understand how something works, we’re far more likely to be motivated to actually do the kinds of exercises that give the specific benefits we want/need. Which is very much the important part!
In short: this book will tell you what you need to know to get you doing the exercises you need to enjoy those benefits—very much worth it!
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Beetroot vs Tomato – Which is Healthier?
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Our Verdict
When comparing beetroot to tomato, we picked the beetroot.
Why?
Both are great! But we say beetroot comes out on top:
In terms of macros, beetroot has more protein, carbs, and fiber, making it the more nutritionally dense option. It has a slightly higher glycemic index, but also has specific phytochemicals that lower blood sugars and increase insulin sensitivity, more than cancelling that out. So, a clear win for beetroot in this regard.
In the category of vitamins, beetroot has more of vitamins B2, B5, B7, and B9, while tomato has more of vitamins A, C, E, and K. We’d call that a 4:4 tie, but tomato’s margins of difference are greater, so we say tomato wins this round.
When it comes to minerals, beetroot has more calcium, copper, iron, magnesium, manganese, phosphorus, potassium, selenium, and zinc, while tomatoes are not higher in any mineral. An easy win for beetroot here.
Looking at polyphenols and other remaining phytochemicals, beetroot has most, and especially its betalain content goes a long way. Tomatoes, meanwhile, have a famously high lycopene content (a highly beneficial carotenoid). All in all, it could swing either way based on subjective factors, so we’re saying it’s a tie this time.
Adding up the sections makes for an overall win for beetroot, but by all means enjoy either or both; diversity is good!
Want to learn more?
You might like:
- Beetroot For More Than Just Your Blood Pressure
- Lycopene’s Benefits For The Gut, Heart, Brain, & More
Enjoy!
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Online Reaction Tests & Women’s Cognitive Health (Test Yours!)
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A team of researchers have looked into the use of online reaction tests (in which, for example, one clicks whenever a certain prompt is shown, or for more of a cognitive challenge, one presses a numerical key when the corresponding digit is shown) to cognitive health in women at different ages.
Why women? To quote the man who had the honor of being the first-listed author on the study (something that happens mysteriously often in science),
❝Women have long been under-represented in healthy aging research, despite making up more than half the population. We developed an easy way to measure cognitive function in the home, without the need for individuals to travel to clinics or receive home visits. Our research shows that testing of cognitive function in the home largely acceptable, easy and convenient❞
About that convenience: they used data from the UK Women’s Cohort Study, which involved over 35,000 British women, and then specifically focused on a follow-up study of 768 participants aged 48–85.
Of the two kinds of online reaction tests we described up top, they used the numerical kind. The participants also filled in a questionnaire about their personal traits (demographic data, mostly, though things like self-reported level of health literacy, and how they would rate their overall health).
What they found
The findings included:
- Younger women were more likely to participate, with participation rates dropping from 89% at age 45 to 44% at age 65.
- Each higher level of education increased the likelihood of volunteering by 7%.
- Women who rated themselves as having “high” intelligence were 19% more likely to participate than those who considered themselves of “average” intelligence.
- Women with lower self-reported health literacy made fewer errors, possibly due to taking longer to decide on answers—consistent with findings from older adults.
You can read the full paper itself here: Health literacy in relation to web-based measurement of cognitive function in the home: UK Women’s Cohort Study
Why this matters
We wrote, a little while ago, about the use of online games (of a specific kind) to improve cognitive function:
Synergistic Brain-Training: Let The Games Begin (But It Matters What Kind) ← the good news is, these are very accessible too
When it comes to rapid and/but correct reactions, this becomes really critical:
How (And Why) To Train Your Pre-Frontal Cortex ← Dr. Sandra Chapman advocates strongly for this, and it’s closely related to working memory and the ability to focus
Want to test yours?
Here are two ways to do it (now, for free, without needing to sign up for anything; the tests are right there on the page):
- HumanBenchmark.com’s Reaction Time Test ← this one’s just a “click when the red panel turns green” test, but the merit here is that it compares your scores to a very large dataset of other people
- Keypress Reaction Time Test ← this one’s the kind that was used in the study, and requires pressing the correct numerical key when the corresponding digit is shown on the screen. You can make it easier or harder by restricting or increasing the range of numbers it uses (default setting is to use the numbers 1, 2, 3, 4, 5, and 6)
Enjoy!
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Rapamycin Can Slow Aging By 20% (But Watch Out)
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Rapamycin’s Pros & Cons
Rapamycin is generally heralded as a wonderdrug that (according to best evidence so far) can slow down aging, potentially adding decades to human lifespan—and yes, healthspan.
It comes from a kind of soil bacteria, which in turn comes from the island of Rapa Nui (a Chilean territory best known for its monumental moai statues), hence the name rapamycin.
Does it work?
Yes! Probably! With catches!
Like most drugs that are tested for longevity-inducing properties, research in humans is very slow. Of course for drugs in general, they must go through in vitro and in vivo animal testing first before they can progress to human randomized clinical trials, but for longevity-inducing drugs, it’s tricky to even test in humans, without waiting entire human lifetimes for the results.
Nevertheless, mouse studies are promising:
Rapamycin: An InhibiTOR of Aging Emerges From the Soil of Easter Island
(“Easter Island” is another name given to the island of Rapa Nui)
That’s not a keysmash in the middle there, it’s a reference to rapamycin’s inhibitory effect on the kinase mechanistic target of rapamycin, sometimes called the mammalian target of rapamycin, and either way generally abbreviated to “mTOR”—also known as “FK506-binding protein 12-rapamycin-associated protein 1” or “FRAP1“ to its friends, but we’re going to stick with “mTOR”.
What’s relevant about this is that mTOR regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, autophagy, and transcription.
Don’t those words usually get associated with cancer?
They do indeed! Rapamycin and its analogs have well-demonstrated anti-cancer potential:
❝Rapamycin, the naturally occurring inhibitor of mTOR, along with a number of recently developed rapamycin analogs (rapalogs) consisting of synthetically derived compounds containing minor chemical modifications to the parent structure, inhibit the growth of cell lines derived from multiple tumor types in vitro, and tumor models in vivo.
Results from clinical trials indicate that the rapalogs may be useful for the treatment of subsets of certain types of cancer.❞
…and as such, gets used sometimes as an anticancer drug—especially against renal cancer. See also:
Research perspective: Cancer prevention with rapamycin
What’s the catch?
Aside from the fact that its longevity-inducing effects are not yet proven in humans, the mouse models find its longevity effects to be sex-specific, extending the life of male mice but not female ones:
Rapamycin‐mediated mouse lifespan extension: Late‐life dosage regimes with sex‐specific effects
One hypothesis about this is that it may have at least partially to do with rapamycin’s immunomodulatory effect, bearing in mind that estrogen is immune-enhancing and testosterone is immunosuppressant.
And rapamycin? That’s another catch: it is an immunosuppressant.
This goes in rapamycin’s favor for its use to avoiding rejection when it comes to some transplants (most notably including for kidneys), though the very same immunosuppressant effect is a reason it is contraindicated for certain other transplants (such as in liver or lung transplants), where it can lead to an unacceptable increase in risk of lymphoma and other malignancies:
Prescribing Information: Rapamune, Sirolimus Solution / Sirolimus Tablet
(Sirolimus is another name for rapamycin, and Rapamune is a brand name)
What does this mean for the future?
Researchers think that rapamycin may be able to extend human lifespan to a more comfortable 120–125 years, but acknowledge there’s quite a jump to get there from the current mouse studies, and given the current drawbacks of sex-specificity and immunosuppression:
Advances in anti-aging: Rapamycin shows potential to extend lifespan and improve health
Noteworthily, rapamycin has also shown promise in simultaneously staving off certain diseases associated most strongly with aging, including Alzheimer’s and cardiac disease—or even, starting earlier, to delay menopause, in turn kicking back everything else that has an uptick in risk peri- or post-menopause:
Effect of Rapamycin in Ovarian Aging (Rapamycin)
👆 an upcoming study whose results are thus not yet published, but this is to give an idea of where research is currently at. See also:
Pilot Study Evaluates Weekly Pill to Slow Ovarian Aging, Delay Menopause
Where can I try it?
Not from Amazon, that’s for sure!
It’s still tightly regulated, but you can speak with your physician, especially if you are at risk of cancer, especially if kidney cancer, about potentially being prescribed it as a preventative—they will be able to advise about safety and applicability in your personal case.
Alternatively, you can try getting your name on the list for upcoming studies, like the one above. ClinicalTrials.gov is a great place to watch out for those.
Meanwhile, take care!
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