tl;dr: Went about as expected, i.e. no obvious effects, with a few mildly interesting observations. Publishing this mainly to push back against the file-drawer effect, and to highlight an example of an experiment which has both a positive expected value and a ~95 per cent chance of failure.
What is the ketogenic diet good for? At the time of writing, the answer is ‘reducing epileptic seizures, probably’. Every other potential benefit has a big old question mark hanging over it. Until recently, I mentally categorised keto as just another trendy and stupidly-restrictive diet.
Then I realised I was thinking about it wrong. A small minority of people report incredible results: either it cures whatever ailment is plaguing them, or it gives them a deep sense of wellbeing that lets them fully embody their authentic self and tear through life like a pure focused laser beam of energy and agency, etc.
I myself have a few ailments I wouldn’t mind curing, mostly of the autoimmune variety, and of course I would like the laser beam thing too.
Even if there’s only a very small chance of getting those kind of results, it totally makes sense to try it out.1 This is a textbook case of the kind of self-experiment I love: capped downside and unbounded upside. The cost is minimal—basically a month of eating in a goofy way—with the potential for life-changing benefits if it does happen to work.
The Keto Experiment Protocol
Keto = eat zero carbs, or as close to zero as possible. The idea is to switch from primarily burning carbs for fuel, to primarily burning fat—either dietary fat, or your own bodyfat.
Some people do keto to lose weight, some do it for health reasons, and some do it to improve energy or mood.
I don’t care about weight loss, so I ate at a small surplus, shooting for ~3200 calories a day. Of that, my goal was to take in fewer than 50g of net carbs,2 and ideally closer to 25g. I didn’t set any limits on protein intake, typically eating about 120-160g a day. Then the rest of my calories came from fat. So much fat. Great big mountains of fat!
I tracked my macros and calories using an app called Macrofactor, which I highly recommend. It was challenging to get enough calories to begin with, but then I settled into a few repetitive meals:
- Breakfast: Keto porridge made with almond meal, flaxseed, chia, heavy cream, whey isolate powder. Topped with walnuts or raspberries.
- Lunch: Four-egg omelette with lots of cheese, mushrooms, capsicum. Topped with avocado and more cheese.
- Dinner: Oily fish with a ton of leafy greens or brassicas cooked in oil, parmesan.
- Shake: Heavy cream, frozen strawberries, whey isolate powder.
- Snacks: Macadamias, almonds, keto cookies, quest bars.
The Dreaded Keto Flu
Ketosis is freaky. We’re born with a whole separate metabolic system which lies dormant for decades, or sometimes our entire lives. No surprise there are a few cobwebs to blow out when we’re trying to get the backup engine running cleanly.
The transition into ketosis often involves headaches, brain fog, lethargy, etc, which generally goes by the name of ‘keto flu’.
In the first week, my energy levels crashed a couple of times, to the point where I fell asleep on the couch at 3pm. I did not feel like a laser beam of focused energy.
But I managed to avoid the keto flu. On reflection, this is probably because I’ve done quite a few extended fasts, which also puts the body into ketosis. My first fasts were definitely unpleasant. Direct quote from a journal entry at the time:
Lay down on the bed but couldn’t drift off. Proceeded to have a nightmare of a night, with nausea, insomnia, and fleeting madness. At one point I must have slept for a few hours, without being aware of it. Drank some more water and finally managed to sleep again.
Now I guess my body is used to switching into ketosis and can do it pretty smoothly, but that wasn’t always the case.3 To the extent that you get the full-blown keto flu, that weighs much more heavily on the ‘downside cost’ side of the equation.
How Hard is it to Stick to the Keto Diet?
If you control the food environment it’s surprisingly OK. My girlfriend joined me in the experiment, which made life a lot easier, both in terms of shared cooking and not having delicious carbs in the house. We brought our own food to a family gathering, and hosted a dinner party where the guests didn’t realise everything was keto. Not bad.
On the other hand, going out for dinner was pretty much off the table. I didn’t have any travel during the month, but that would have been pretty niggly too, and probably I would have compromised in some way.
If I didn’t eat fish, keto would have been harder, but still doable. If I were a strict vegetarian, i.e. no eggs or dairy, it would have been impossible. Eggs, cheese, cream, and whey were a central part of my diet.
The repetitive meals did start getting a little stale, even for someone like me who loves that kind of thing. This is good if your goal is weight loss, but it wasn’t ideal for my purposes. When you’re trying to smash a ton of calories, a mixture of carbs and fats is definitely easier than fats alone.
What Happens if You Drop Out of Ketosis?
First you should know whether you’re in ketosis in the first place. This means checking your levels of ketone bodies. You can either pee on a stick, measure your breath (which should smell like nail polish remover) or take a blood test.
But as far as I can tell, these tests are unnecessary, or in some cases bullshit. If you’re only eating trace carbs over a period of days or weeks, you’re either in ketosis or you’re dead. Nevermind what the piss-stick tells you.
What about minor diet violations? Let’s say you eat 20g of carbs above the level that would keep you in ketosis. That’s 80 calories, or about 4% of a day’s energy expenditure. So in the worst case, maybe you get bumped out of ketosis for an hour. Then what happens? The carbs are gone, there’s nothing else to metabolise but fat, so you go back into ketosis.
Maybe there’s some mechanistic thing I’m missing here, but basically, as long as you’re strictly avoiding non-fibrous carbs, you should be good. (If you’re regularly having ‘cheat days’ and don’t track your macros properly, not so much.)
Results of the Keto Experiment
We’re looking for big, obvious results, or nothing at all: I don’t think it’s worth running keto just to pick up marginal improvements, especially considering they might be random noise or placebo.
On the mental side of things I didn’t track any concrete metrics, so this is purely vibes-based. And the results were…a big fat nothing! I guess I had less post-meal sleepiness? But the changes were nowhere near dramatic enough to write home about.
My autoimmune situation was unchanged. Mildly disappointing, but I knew it was a long shot. Sleep was worse at first, then it normalised. I didn’t track bloodwork so don’t have any more data than that.
Physically, I felt a little deflated with muscles starved of glycogen, but had no problem completing my workouts, and continued gaining strength roughly as planned. My girlfriend was able to do 3km swims without any problems, which was a lot more surprising.
Would I do the Keto Diet Again?
Despite the underwhelming results, I weirdly enjoyed this experiment—it got me cooking more creatively4, it accidentally nudged me into more healthy eating e.g. a shitload of greens and Omega-3s, and it eliminated my cravings for sugar, which I’d noticed becoming a bad habit after meals.
There is a meme in the keto community that it takes some time to become “fat adapted”, as distinct from merely entering ketosis, and that this period might be as long as three months. The concept is totally nebulous, but keto advocates might say I stopped too soon to realise the true benefits.
What if they’re right? I highly doubt it, but I’m kind of tempted to do this again. Next time I’d do it during a phase where I’m trying to lose weight, where I think it’ll be a real weapon—I can get all the satiety benefits, and it’ll also be easier to sustain for a long time, since I’ll be eating restrictively anyway.
In conclusion: keto was definitely worth a try. I’ve been slipping on the self-experimentation front lately, and it feels good to get back after it.
If you have e.g. fatigue, obesity, brain-fog, or autoimmune conditions and you’ve exhausted all the normal treatment options, the expected value of these kind of random experiments is a lot higher: merely getting back to a baseline level of health and energy is a huge win.
If your health is already normal, then the equation is less compelling. Still, as far as experiments go, you could do a lot worse.
- Conditional on some of those glowing endorsements coming from people I trust, and at least some plausible mechanistic pathway. Otherwise this argument for trying stuff would be way too general: it’s easy to find people who swear by all kinds of quackery.
- ‘Net’ means excluding carbs from fibre. This makes it easier to eat veggies and even some fruit without going over the limit: 100g of raspberries has 6.5 grams of fibre and 5 grams of net carbs, for example.
- I also made sure to eat a ton of salt, because I suspect a lot of keto/fasting problems are dehydration in disguise (including that gnarly night from the journal, which happened after I’d hiked ~10km without taking extra electrolytes). Each gram of glycogen is bound to three or four grams of water, which all gets flushed out in the first few days—this is what causes the rapid ‘weight loss’ that people get so excited about.
- Keto cookbooks remind me of the rules-lawyering shenanigans that observant Jews use to get around Shabbat restrictions. There’s a keto-fied version of every ‘junk’ food you can imagine: I tried cauliflower pizza, zero-carb cheesecake, and almond-flour cookies, among other Frankenstein-like creations.
I majored in dairy science in college and ketosis in cattle was considered a disease not a diet option. While I absolutely realize that we are not ruminants, I would still be too scared to try it! My daughter and her husband did it for a while and lost weight but agreed that their weight loss was probably mostly due to the removal of beer and desserts from their diets. I do find sensible self experimentation interesting however and appreciate your sharing your experience with us. Every year, I give up sweets and most alcohol for Lent and feel so much better. And every year, I slide back into old habits after Easter. I am not even sure why. Right now, I have been adding power yoga to my routine and, after about six months, I am seeing lots of upside and almost no downside to this experiment.
I have not been able to successfully stick to a keto diet – due to lack of willpower. But, I have read quite a bit and tried it a couple of times. Everything I read said that you can’t get the benefits of the diet (regardless of whether you want to lose weight or for other reasons) unless you eat less than 20g net carbs a day. And it DOES matter if you go in and out of Ketosis. I am not sure that if you don’t follow the actual “rules” it was a valid experiment. If you want to try it again I would ensure you followed a plan rather than a DIY version. I did a variation for weight loss for about 7 weeks and if I strayed off it at all I stopped losing weight and any benefits. But, fun experiment anyway – and thanks for posting your thoughts and results!!
Hi Aisling, thanks for sharing your experience. I’m confident that I was in ketosis (fruity breath, pee-sticks showed elevated ketone bodies), and I can’t see any mechanistic reason why minor lapses would matter, but you’re right—perhaps next time I’ll get a breath or blood meter, so I can test that out.
My guess is that 20g is given as if it were an ironclad rule because it’s maximally conservative, with the knowledge that people will fudge it. The real number will be specific to each individual, depending on things like body size, activity levels, history of fasting/keto, how ‘deep’ in ketosis they are, etc.
Exciting to see you back! 🥳 🤗
I’ve had some obese friends successfully lose weight on keto when nothing else worked but it’s never seemed worth it to me to try because (a) if I lost much weight I would quickly die, (b) I’m lactose intolerant, and (c) I’m allergic to the majority of sugar substitutes. Unbounded upside? Perhaps. I’m a sickly little thing. But also keto flu sounds terrible? And the whole thing sounds… hard.
So… that’s my uninteresting two cents. I didn’t previously understand what ‘net’ carbs were so thanks for that! Yay blog posts!
Hi Claire! 😃
Bummer re: the sugar substitutes—I didn’t think to include it in the post, but I ate quite a lot of erythritol in things like protein bars and desserts. And yeah, doing it without dairy would have been really hard.
That’s really cool that it worked out for your friends. I agree that the equation doesn’t look so compelling for you. If longterm adherence is gonna be really hard due to e.g. veganism or food allergies, the benefits on the other end better be nothing short of life-changing!
What’s up Rich. I’m glad you still contribute to your blog, you’re my favorite writer on the webs. I’m on my second read of your book and had a toilet thought I’m sure you have considered; any plans on a hardcover edition of your book in the future? Limited release or otherwise?
Hey thanks Carlos. I’ve vaguely thought about it! Amazon recently introduced print-on-demand hardcovers, but they’re that kinda lame ‘case’ version with the design printed onto the cardboard. I’d be more interested in the luxe cloth-bound style, but I’d have to organise it through a third party, which would be a) very expensive, and b) probably a vanity project, given projected sales. So it’s possible, but unlikely. Depends how vain I get.
I went on keto 5 months ago for weight loss. I lost almost no weight for 2 months but stayed on it because my back and joints felt great. For me (an old guy) the asymmetrical payoff was better than expected.
Nice. Are you still on it semi-permanently?
When dark mode? I feel like I’m staring into a lightbulb.
Not sure if an out-of-the-box plugin will work with my custom CSS but I’ll see what I can do.
fwiw I use Dark Reader on Chrome and it has no problem with this site! Perhaps an option for Jon?
It’s hard to loose weight when consuming cream and cheese every day. Perhaps next time try non-dairy alternatives. Consuming cow’s milk is linked to a heightened risk of cancer anyway.
I’m not trying to lose weight 😉
Carnivore next time??
Not a goer for me personally, and seems more likely to have unintended consequences. I might try it if I was at my wit’s end with some kind of treatment-resistant problem, but otherwise, pass.