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The health metric that is most predictive of future disability risk - and it's not what you think. · Hardiness with Dr Paul Taylor

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  Speaker 1: Hey, everyone, welcome to another edition of Wisdom Wednesdays. Now,
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  Speaker 1: before we get into this week's episode, for those of
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  Speaker 1: you who like to read thoughtful pieces, head over to
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  Speaker 1: substack dot com at Carly Taylor Coaching. So every Tuesday,
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  Speaker 1: Carly is writing an article with grinded insights from Eastern,
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  Speaker 1: ancient and modern philosophies and these will be practical ways
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  Speaker 1: to navigate your thoughts, emotions, and the challenges that come
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  Speaker 1: with being human. Now let's get on with the podcast.
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  Speaker 1: So let's imagine you don't go to your doctor that regularly,
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  Speaker 1: So you go in for like an annual medical There'll
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  Speaker 1: be certain things that will be done as a matter
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  Speaker 1: of routine. Your doctor will measure your blood pressure, they
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  Speaker 1: will talk about your family history, and they'll probably measure
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  Speaker 1: your height and your weight in order to calculate your
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  Speaker 1: BMI your body mats index. What they probably won't do
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  Speaker 1: is wrap a tape measure around your waist. And according
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  Speaker 1: to a newly published analysis, this could be a real
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  Speaker 1: mistake in preventative medicine. So paper that has just been
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  Speaker 1: published in the journal gyro Science by the author Ben
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  Speaker 1: Hassen at al. So. It was published in twenty twenty
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  Speaker 1: six and had data from a long running study of
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  Speaker 1: British civil servants called the Whitehall two study. And as
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  Speaker 1: part of this ongoing investigation around British civil servants and
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  Speaker 1: their health, and the researchers in this study ask a
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  Speaker 1: very simple question, which physical measurement best predicts whether an
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  Speaker 1: old or adult will lose their independence over the next decade.
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  Speaker 1: So it wasn't talking about Cardiovascar's's or diabetes or mortality.
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  Speaker 1: It was talking about functional independence. That's the ability to
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  Speaker 1: dress yourself, to bathe independently, to get in and out
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  Speaker 1: of bed, to walk, to use the toilet, to feed yourself.
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  Speaker 1: Because ultimately, for most people, this is what healthy aging
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  Speaker 1: actually means. It's not just about living longer, but it's
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  Speaker 1: about staying physically capable, and it's obviously linked to health
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  Speaker 1: span rather than lifespan. So in the paper, the researchers,
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  Speaker 1: as I said, they used the data from the White
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  Speaker 1: Hole to cohort. This is one of the most respected
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  Speaker 1: aging data sets in the world and it's followed Berty
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  Speaker 1: civil servants for decades. And in this analysis they included
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  Speaker 1: four five hundred and ninety three adults and the average
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  Speaker 1: age was sixty five point three years. Thirty one percent
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  Speaker 1: were women and the rest were men, and they had
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  Speaker 1: a median follow up of eleven years. So this actually
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  Speaker 1: gives us a really good overview is you go from
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  Speaker 1: mid sixties into late seventies and a baseline. The participants
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  Speaker 1: underwent a battery of standard physical function assessments, the kind
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  Speaker 1: of things that gerryeticians actually use, and they evaluated ten
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  Speaker 1: candidate predictors. First was waste circumference, then BMI body mass index.
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  Speaker 1: They looked at walking speed, timed chure rises, getting up
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  Speaker 1: out of the chure, and one leg balance, grip strength,
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  Speaker 1: long function, and they used FEV one, but they also
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  Speaker 1: did another long function peak expiratory flow. Then they did
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  Speaker 1: self reported physical activity, and last were a number of
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  Speaker 1: different frailty indicators, and the primary outcome that they were
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  Speaker 1: interested in was what's called incident disability. That's defined as
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  Speaker 1: difficulty performing one or more activities of daily livings and
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  Speaker 1: severe disability meant difficulty with two or more activities of
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  Speaker 1: daily living. And they also looked at mortality, which is
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  Speaker 1: important because they weren't asking which metric correlates with health.
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  Speaker 1: What they were asking was if I measure something today,
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  Speaker 1: what best predicts who will lose independence over the next
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  Speaker 1: ten plus years. So that is a much more clinically
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  Speaker 1: useful question, and it has practical implication for all of us.
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  Speaker 1: So let's explore the results. So the answer and you
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  Speaker 1: can have a cracking and have a guess at it.
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  Speaker 1: It wasn't what most clinicians might expect. It wasn't what
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  Speaker 1: I expected. It wasn't walking speed, it wasn't grip strength,
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  Speaker 1: which I would have thought would be it because it's
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  Speaker 1: a potent predictor of longevity, and I've talked about it before.
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  Speaker 1: It wasn't balanced, it wasn't lung function, it was waste circumference.
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  Speaker 1: Waste circumference produced the strongest predictive discrimination for future disability,
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  Speaker 1: and it outperformed BMI significantly, And that really matters because
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  Speaker 1: BMI used all the time. It's one of the most
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  Speaker 1: overused and least nuanced screening tools in medicine. BMI tells
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  Speaker 1: you your total mass relative to your height, but it
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  Speaker 1: doesn't tell you where the fat is stored, how much
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  Speaker 1: muscle you have, how metabolically active your tissue is, and
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  Speaker 1: whether that person is carrying dangerous and visceral fat or
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  Speaker 1: visceral adipocity. So two people with identical BMIs kind of
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  Speaker 1: radically different risk profiles. You can have two people with
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  Speaker 1: the same height and the same way. One could be
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  Speaker 1: a super fit rugby player with lots of muscle, and
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  Speaker 1: another one could be a completely sedentary adult with lots
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  Speaker 1: of fat. So BMI is next to useless and particularly
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  Speaker 1: for predicting things like they wanted to look at in
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  Speaker 1: this study. Now, the researchers they then use something called
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  Speaker 1: Lasso machine learning modeling to determine the smallest set of
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  Speaker 1: men measures that maximize predictive performance, and the final model
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  Speaker 1: for disability included age, sex, waste circumference, walking, speed, churizes,
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  Speaker 1: and balance. And again I was pretty shocked that grip
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  Speaker 1: strength wasn't in there, but this is what the study said.
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  Speaker 1: Now for severe disability, walking speed actually dropped out of
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  Speaker 1: that list, so it was aided sex, waste circumference, walking arises,
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  Speaker 1: and balance. But here's the clinically fascinating bit. Adding all
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  Speaker 1: of those extra performance tests only marginally improve prediction compared
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  Speaker 1: with waste circumference alone. In other words, a cheap measuring
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  Speaker 1: tape did most of the heavy lifting. When it comes
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  Speaker 1: to predicting who loses their functional independence. So why would
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  Speaker 1: waste circumference be so predictive, Well, it turns out is
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  Speaker 1: because waste circumference is acting as a proxy for something
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  Speaker 1: far more important, which you probably already know, and that's
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  Speaker 1: visceral at a post tissue or visceral fat. This is
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  Speaker 1: the fact that it's underneath your stomach muscles and surround
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  Speaker 1: your organs, and it is biologically nothing like the fat
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  Speaker 1: that you can pinch unto your skin. That's called subcutaneous fat,
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  Speaker 1: and that is largely passive energy storage. But visceral fat
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  Speaker 1: is metabolically aggressive. It behaves like an endocrine organ and
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  Speaker 1: produces its own hormones called atopokinds. So let's take a
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  Speaker 1: deep dive into the mechanisms by which visceral fat is
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  Speaker 1: so dangerous because there are five of them that interact
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  Speaker 1: with each other. The first is chronic inflammatory signaling. So
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  Speaker 1: these visceral what they are called adopocytes, These are the sales.
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  Speaker 1: They are highly secretary. They release They release inflammatory molecules
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  Speaker 1: like TNF alpha interlookin six, MCP one resistant, and something
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  Speaker 1: called pleusminagen activator inhibitor one. I don't know how they
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  Speaker 1: come up with the steams. But anyway, now all of
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  Speaker 1: this together creates a low grade systemic inflammation, and many
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  Speaker 1: of you know that low grade inflammation accelerates biological aging.
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  Speaker 1: But there are multiple pathways. We get endothereal dysfunction, we
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  Speaker 1: get oxidative stress or mitochondria become impowered, we get reduced
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  Speaker 1: anabolic or growth signaling, and we get accelerated muscle breakdown.
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  Speaker 1: And over time this erodes our physical reserve. The person
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  Speaker 1: doesn't suddenly become free. They slowly lose function and resilience.
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  Speaker 1: And what happens is recovery from illness takes longer, strength declines,
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  Speaker 1: mobility declines, and function declines. Then the second mechanism is
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  Speaker 1: insulin resistance and metabolic inflexibility. So this visceral fat. It
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  Speaker 1: dumps free fatty acids directly into the liver circulation and
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  Speaker 1: basically this drives insulin resistance in the liver. The consequences
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  Speaker 1: here are higher fasting glucose, elevated insulin. We get increase
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  Speaker 1: what's called dounovo lipogenesis, which is then creation of fat.
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  Speaker 1: We then get a fatty liver and we get impowered
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  Speaker 1: glegogen regulation. But the effects don't stop there. That lipid
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  Speaker 1: or fat spillover reaches your muscle and that fat accumulates
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  Speaker 1: inside the muscle. And I've actually done a podcast on
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  Speaker 1: this before and how dangerous that intramuscular fat is because
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  Speaker 1: it interferes with insulin receptor signaling. Basically, your muscle is
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  Speaker 1: the most efficient thing at using glucose, and when it
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  Speaker 1: becomes invated with fat, it becomes less efficient to glucose uptake.
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  Speaker 1: Your mitochondria then become dysfunctional. Then your energy production falls,
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  Speaker 1: and if your muscle becomes metabolically impowered, your function suffers.
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  Speaker 1: Your walking speed drops, your chair performance declines, fatigue increases,
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  Speaker 1: and that directly connects metabolic dysfunction to disability risk. Then
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  Speaker 1: the third mechanism is those adipokind dysfunction. So healthy fat
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  Speaker 1: isn't inherently bad, right, This is why we need to
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  Speaker 1: be looking at waste circumference, because it's that stuff that
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  Speaker 1: is actually dangerous. The healthy fat actually produces protective hormones
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  Speaker 1: and one of those is called autoponnectin. So autoponnectin actually
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  Speaker 1: improves your insulin sensitivity and reduces inflammation, protects your blood vessels,
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  Speaker 1: and it supports fatty acid oxidation, but visceral fat suppresses autopnnectin,
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  Speaker 1: so it's not its own direct mechanism. But then it
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  Speaker 1: suppresses the signals from your healthy fat and at the
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  Speaker 1: same time leptin rises, and that can cause something called
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  Speaker 1: leptin resistance. No, what happens with leptin resistance. You get
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  Speaker 1: impowered appetite regulation because leptin is the off switch for eating,
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  Speaker 1: You get worsening energy dysregulation, you get progressive fat gain,
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  Speaker 1: and you get greater metabolic dysfunction and leptin. Actually, when
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  Speaker 1: you've got leptin resistance, you're less likely to move as well,
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  Speaker 1: and becomes a nasty, vicious cycle. Then the fourth mechanism
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  Speaker 1: is what we call sarcopenic obesity. So this is where
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  Speaker 1: things get especially relevant for aging. A person can carry
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  Speaker 1: access visceral fat and have declining muscle mass. This is
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  Speaker 1: what we call sarcopenic obesity or skinny fat, and that
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  Speaker 1: combination is toxic because muscle is metabolically active. It produces
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  Speaker 1: all these miokinds that are so good for your health.
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  Speaker 1: But it is your organ of independence. You need it
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  Speaker 1: for getting off the floor, standing up from the church
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  Speaker 1: climbing stage, maintaining your balance preventing your falls. But visceral
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  Speaker 1: fat accelerates muscle loss through these inflammatory cytokines, insulin resistance,
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  Speaker 1: anabolic resistance, and mitochondrial dysfunction, and this creates sarcopenic obesity,
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  Speaker 1: and that's one of the strongest predictors of frailty and disability.
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  Speaker 1: And then the last mechanism is vascular aging. So visceral
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  Speaker 1: fat strongly correlates with high blood pressure endothelial dysfunction, so
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  Speaker 1: the endotheal sales are the ones that make up your
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  Speaker 1: vings in your arteries. It also creates athlosclerosis and microvascular
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  Speaker 1: disease and poor blood flow that results from all of
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  Speaker 1: that means poor oxygen delivery to your tissues, to your muscle,
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  Speaker 1: to your brain. And what that means is you get
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  Speaker 1: more fatigue, you get exercise intolerance, you get cognitive decline,
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  Speaker 1: and you get physical decline. So the are the five
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  Speaker 1: mechanisms that interact with each other. Let's just talk briefly
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  Speaker 1: about why BMI misses this entirely because it is crude.
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  Speaker 1: Like I said earlier, the seventy five kilo rugby player
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  Speaker 1: in the seventy five kilo century metabolic on healthy individual,
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  Speaker 1: they got the same BMIs or in the same category,
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  Speaker 1: but they have why highly different physiology. And BMI does
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  Speaker 1: not distinguish between muscle and fat, it doesn't distinguish between
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  Speaker 1: visceral and subcutaneous fat, and it doesn't distinguish between metabolically
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  Speaker 1: healthy versus unhealthy obesity. Waste circumference captures most of that now,
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  Speaker 1: not perfectly, but it is far better than BMI, and
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  Speaker 1: it's something that can be used cheaply effectively across the population,
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  Speaker 1: and you can do it as well. So the practical takeaways, Now,
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  Speaker 1: this doesn't mean that grip strength isn't important, because we
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  Speaker 1: know it is hugely important. It doesn't mean that walking speed,
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  Speaker 1: strength training, and balance don't matter. They obviously do, but
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  Speaker 1: they are critical markers of what we call functional reserve.
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  Speaker 1: This paper is about screening efficiency, like what's the best
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  Speaker 1: screening thing that we can actually do. So I don't
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  Speaker 1: want you to lose sight of the importance of grip
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  Speaker 1: strength and strength training and all of that walking speed,
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  Speaker 1: but we're just talking about a screening to and if
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  Speaker 1: you want one quick metric that tells you a lot
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  Speaker 1: about your personal future risk waste circumference is one of
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  Speaker 1: the most important tools that we have. So in order
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  Speaker 1: to measure it properly, get your tape, have it at
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  Speaker 1: the level of your belly button. You stand relaxed, take
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  Speaker 1: a breath in and then breathe out so you're not
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  Speaker 1: sucking in your stomach. You just exhal normally and make
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  Speaker 1: sure the tape is parallel to the floor all the
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  Speaker 1: way around. Don't suck your stomach in and that you
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  Speaker 1: just basically measure that, and you track your trend, and
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  Speaker 1: it's the trend that also matters. Your number matters, but
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  Speaker 1: so does your trend. So what should that number be, Well,
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  Speaker 1: you want it to be reasonably low. For women, you
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  Speaker 1: want it to be less than eighty centimeters or thirty
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  Speaker 1: one and a half inches, and for men, and you
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  Speaker 1: want it to be definitely less than ninety four centimeters
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  Speaker 1: or thirty seven inches. Now, different health bodies have got
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  Speaker 1: different once, but this is where at above that level
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  Speaker 1: that you start to have really significant increased risks, and
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  Speaker 1: those risks become really substantial. At eighty eight centimeters or
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  Speaker 1: thirty five inches for women and one hundred and two
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  Speaker 1: centimeters or forty inches for men, And this is where
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  Speaker 1: I actually think we're going wrong as a society. And
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  Speaker 1: this is a bit of a sensitive topic, but the
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  Speaker 1: whole idea of the of the body beautiful and you know,
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  Speaker 1: you can be any size and that's okay, I actually
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  Speaker 1: personally do not agree with that. While I am completely
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  Speaker 1: against fat shaming and people wanting to be really skinny,
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  Speaker 1: just saying that any size is okay without highlighting the
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  Speaker 1: risks to people, I don't think that's okay. Yes, we
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  Speaker 1: need to get away from this idea that self worth
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  Speaker 1: ties to how you look, or those sorts of things
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  Speaker 1: that we should all be skinny. You don't need to
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  Speaker 1: be skinny, and I've said many many times, you're better
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  Speaker 1: to be overweight and fit than normal weight and completely unfit.
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  Speaker 1: But the nuance there is around your way circumference. So
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  Speaker 1: my advice is to get that measured. And if you're
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  Speaker 1: above those cut off, particularly the higher level cut off,
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  Speaker 1: we know from the science now they getting yourself below
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  Speaker 1: that cut off at least the higher level cut off
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  Speaker 1: will really pay dividends for you in terms of your
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  Speaker 1: future life. So that's it for this week, folks, Catch
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  Speaker 1: you next time.