This Keto Life: The trouble with n=1

I recently returned from a wonderful ten day holiday in Indonesia, staying on the island of Gili Air and diving nearly every day (and I saw turtles on every dive. Only one shark this time though). While I’m on holiday, I don’t tend to eat keto, in spite of the damage this will cause. It’s just too complicated and difficult and two weeks won’t do a huge amount of damage.

Besides. Margaritas.

So I come back, having gained some water weight (and some non-water weight, because nom), and feeling sluggish and bloated, but hopefully not having given myself the usual long-term consequences (I did develop an abscess, probably due to increased inflammation – ugh – but it was tiny and I managed to blast it with antibiotics).

Here’s one thing that I find interesting: when I first went keto, my resting heart rate (RHR) went up. Not a huge amount, maybe 6 bpm, but it definitely increased from a stable point. I thought this was odd, but didn’t pay it too much mind.

Now, I have a Charge HR, and thus a continuous heart rate monitor. It’s true that it’s not the most reliable monitor, and also that the way it calculates “resting heart rate” is a little bit bogus (if you’re not moving, it thinks you’re resting. Maybe you are. But maybe you’re absorbing some profoundly stressful news, or reading an exciting book with cliffhangers. You see the problem).

The trends, however, are very reliable.

When I break keto, my RHR pounds to the sky, usually maxing out at about 73. When I get back on keto, it starts to plummet – my usual RHR (at least according to the Fitbit) sits somewhere between 57 and 60.

I am tempted to assume – and there is some good evidence for this – that this is because my body is now better adapted to a low carbohydrate, ketone-based metabolism, and so I run more efficiently when that’s in operation.

Here’s the problem: I’m one person, with a complicated body. There are a number of other things it could be.

It could be that my overall inflammation is lower when I’m on low-carb. This is well supported in the literature, and would interact with my Crohn’s (which is, after all, an inflammatory autoimmune condition).

It could be that I’m less anxious because I have predictable control over my diet (I plan a lot when I’m on keto and I find that comforting). The reason I don’t think that this is the case is that when I’m on holiday, I’m not stressed at all about food choices. I give myself free rein. All the same, it’s a plausible hypothesis that there is some underlying anxiety – I’m usually away from my home and my comfort zone and surrounded by strangers when I’m on holiday, so it wouldn’t be a surprise that my RHR is a bit elevated.

It could also be hormonal. I’ve noticed that my RHR is locked in very tightly to my hormonal cycle, and skyrockets around ovulation time, dropping off when the period arrives. And I did get my period about a day after I got home. So this is plausible – but again, it’s not always the case with the keto RHR changes.

What I suspect has happened is that going back on keto has lowered my inflammation, and that this has interacted with my hormonal cycle as well, because both of these things affect my RHR.

But I don’t know. I won’t ever know. Because there’s no way to test this with n=1. You’d need a wide sample of male and female people with active ileal Crohn’s disease, some of whom have adapted to a keto diet and some of whom haven’t, and then you’d need to monitor their RHR as they went on and off keto, to see if it changed, and how much.

This bugs me, because of who I am. I want to use it as supporting evidence that keto is good for me (I have a bunch of evidence for that already, but I get anxious, because it still is considered a really weird way to eat, and I get nervous when I stand out from the crowd, and already I have social anxiety around food choices), but I can’t be 100% sure (or even 95% sure with a basic p-value of 0.05) that this is what the relationship is, between ketone-based metabolism and cardiovascular efficiency.

The above is why I always narrow my eyes whenever anyone says “Well, [thing that is shown to be a placebo or worse] always works for ME.” Because maybe it does, and people do know their own bodies, but maybe it’s comforting, and anxiety is a factor, or maybe there’s something else that is correlated with that practice, and maybe…

Yeah. I’ve been told by a GP that perhaps I “over-science” my health.

All the same, it’s strangely fun.

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2 thoughts on “This Keto Life: The trouble with n=1

  1. You may already know this, and we may already have had this conversation, but … learning about designing epidemiological (or clinical trial) studies based on counterfactual thinking BLEW MY MIND and has shaped how I do my job and think about the way I talk to other people. When you’re trying to prove something works or doesn’t work on a population level, well-designed trials and a statistical power analysis are important, but sometimes you just have to look out for yourself. And an n=1 trial is absolutely useless for telling other people what they should do, but if it makes you feel better and it’s something you can live with, then who cares if it’s generalisable to other people?

    PS Thankyou for being that sort of scientist who refuses to use “it made me feel better” as an excuse to spout unproven theories at people and instead just spends their time doing actual science.

    • Ah, no worries, and I accept your apparent gratitude!

      I mean, in terms of unproven theories, it gets complicated – there are plausible reasons why keto is good for some people with Crohn’s, but IBD in general is incredibly idiosyncratic, and everyone’s intestinal tract is different. Plus, it all interacts with what your pancreas, gall bladder, liver, and intestinal lining have had to deal with throughout your whole life, and the general inflammatory environment, and gut flora – godDAMN gut flora. When I explained the whole thing to Surgeon Sam, he nodded and said it made sense and I was doing the right thing (he seemed to understand why I was nervous about it). When I explained it to my GP, she frowned and ordered a lipid panel, then looked at the results and told me to keep doing what I’m doing.

      I mean, I say all that, because I’m deeply insecure about flouting the accepted one-size-fits-all wisdom of diet and nutrition and trying not to care that anyone else might think I’m being a nutter. Given the plethora of symptoms that follow on from any long-term abandonment of keto (cf. holiday abscess – sigh), I should be pretty confident by now, right? (but then again, maybe I secretly want to be wrong, which is fair, because pizza is amazing. So every time I break, I think “maybe THIS time I won’t get symptoms x,y and/or z, because if I don’t, I can order pizza, baby”.)

      And when you find something that works, it is SO TEMPTING to want everyone with any vaguely related health problem to try it, because you want to help, and if your experience can help, that would be amazing! So I understand where that urge comes from, and I’m probably a bit more patient with it than I have to be. But I don’t do that, because not only is there the “n=1” problem, there’s the absolute hard fact that keto is (1) difficult, (2) restrictive, (3) often expensive, (4) contraindicated for some conditions, and finally (5) just not going to work at all for some people. Like, it looks as though it would be great for some people (genetic predisposition to insulin resistance), and terrible for others (poor fat absorption and metabolism would kick it right out), and for most people it would just be “oh, well, this is different?” In terms of athletics, it’s great for long endurance (marathons), terrible for explosive power (sprints, martial arts).

      And I could totally vomit that information at people at the drop of a hat (I mean, I do to people like yourself, but that’s because you’re a biologist, and I think it’s interesting biology, not because I think you should start drinking butter), but… no. Because I also know what it’s like to be told that my hypermobility syndrome would be better if I took more vitamins (REALLY), and that my depression would be better if I just exercised more (MORE?! Do these people KNOW how much I work out?!), and that Big Pharma wants me to be on immunosuppressants to make me sick, and that I shouldn’t take painkillers because they’re bad for me… so unless someone specifically asks, I keep my mouth shut.

      Anyways, this has been my “I am so conflicted” rant, thank you for reading.

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