I’ve done a few experiments with the ketogenic diet in the last few years, inspired by Tim Ferriss. People asked me for info about it so I decided to write it up.
The ketogenic diet induces ketosis, a metabolic state where most of the energy delivered to your cells comes not via glucose (sugar) molecules but instead via ketone molecules. Ketones are produced from fat, and my understanding is that ketosis is how humans evolved to survive for long periods without food — when you fast for several days you pretty much always end up in ketosis as your body starts consuming your fat reserves for energy.
To get into ketosis can be a challenge. You can either fast for 3 days, or jump directly into a ketogenic diet where you are eating basically no carbs; it takes anywhere from 1-3 weeks to properly adapt if you do this. I don’t really understand the mechanism of the adaptation process or why it takes that long, but that’s what people say; the adaptation can be anywhere from mild tiredness/low energy to dramatic flu-like symptoms (they call it the “keto flu”), but is rarely symptom-free. Fasting is a quicker way to enter ketosis, but it is hard to do anything when fasting because you’re so low energy.
Once in ketosis, you want to eat less than ~20g of carbohydrates-that-convert-into-glucose per day. For some dumb reason on US nutrition labels, “dietary fiber” counts towards total carbohydrates but isn’t processed into glucose, so keto websites will talk a lot about “net carbs” which is just total carbs minus dietary fiber. You can eat as much fiber as you want.
Micromanaging carbs is expensive, and the 20g limit is not strict — it’s just a number where most people will stay in ketosis. So in my first keto experiment I looked up everything I ate and counted my carbs for a week (here’s a carb chart from /r/keto), but beyond that point I just developed a general idea of what kinds of foods I can and can’t eat based on carb counts, and so after that point I just stuck to low-carb foods but stopped counting.
Effects of Ketosis
Being off sugar and sweet things for a week or two, I noticed a really dramatic increase in my sensitivity to sweetness. Beer which I used to like, including things like high-gravity imperial stout and Belgian strong dark beer, became cloyingly sweet, whereas IPAs became drinkable instead of too bitter. 85% dark chocolate went from “too bitter” to perfectly sweet. Sugary soda became completely undrinkable.
I also noticed a nice energy-smoothing effect. Normally when you eat carbs, you generate a lot of glucose, and then your body compensates by generating insulin, which causes your fat cells to suck up a bunch of glucose to save it for later. So, in other words, during normal metabolism you get a sugar high followed by a crash once the insulin comes out. This is the cause of the “post lunch lull” that a lot of people experience. On ketosis, there is no insulin equivalent (I guess), but ketones are slower to produce and consume — so you just have a more leveled-out amount of energy with basically no high/crash cycles. I noticed this while on keto, although it was subtle most of the time, but I definitely felt like I had real energy to work on projects in the evenings when (on a normal diet) I’m tired enough to only want to play video games or watch videos.
I didn’t lose weight, but I wasn’t trying to; it did seem like it would be pretty easy to lose weight on keto by slightly under-eating but I was already at the weight I wanted to be at.
I did experience weird muscle cramps. I believe this was due to sodium deficiency. I don’t fully understand it, but when on keto your body excretes a lot more sodium than normal and so you have to eat extra salt in order to keep levels up. Once I realized this I would eat a salty bouillon broth before bed every night — if I forgot, I would sometimes wake up with painful cramps in my calf muscle.
What did I eat?
On keto your meals look weird: you need to eat what seems like an absurd amount of fat and protein to make up for missing calories from carbs. Carbs tend to be the cheapest calories, so restaurants generally prefer to serve you carbs to save money - this makes it hard to find restaurants where you can eat keto.
- Breakfast: Coffee with butter. Bacon and eggs.
- Lunch: A giant salad with tons of fatty salad dressing, avocados, and roast chicken
- Afternoon snacks: Brie cheese and nuts; chicken broth
- Dinner: Coq au vin. Frittata. Zucchini noodles with curry sauce. Slow cooked beef stew. Chicken tikka masala with cauliflower rice.
- Dessert: One square of 85%+ dark chocolate. Chocolate mousse with stevia sweetener. Zero carb cookies made with almond flour.
Keto was a neat excuse for me to learn to use a lot of cooking techniques I might not have bothered with otherwise. For example, I learned to make my own Caesar dressing with an immersion blender from eggs and oil. I made my own chicken stock by boiling carcasses. I learned about zucchini noodles and got a spiralizer so I could make zoodles whenever I wanted. I learned about all sorts of fun alternate flours and sweeteners so I could experiment with baking keto desserts, keto pizza and such. I braised and slow-cooked lots of meats.
Should you try keto?
If you’re the type with a sweet tooth that you’d rather not have, I expect a 3-day fast plus a week of keto would be a really effective intervention to reset your sensitivity to sweetness.
If you want to lose weight, you should definitely experiment with keto; I had to eat a more food than I really wanted in order to maintain my weight, so I expect it would be easier than usual to eat fewer calories.
If you are affected by a midday or evening crash, it is probably worth a try to see if you get an energy smoothing effect like I did.
The shift to only eating low-carb foods was easier than expected — it was annoying to do all that work to figure out what to eat, but for a few weeks at least, the novelty outweighed the annoyance and so I really ended up enjoying the meal planning on keto even though it was more time-intensive.
The hardest part was staying on it against social pressure. Going out to eat with friends all the time becomes impractical; it is certainly possible to order something keto-compatible at most sit-down restaurants, but lower-end casual places like pizza and Chinese tend not to have a single thing you can eat; and even at nicer places it can be hard to get a meal-sized amount of calories. For example, at Japanese places you can order sashimi but you might be spending $50+ to get enough sashimi for a full meal. At a steak house you can eat the steak but not the potatoes, and just steak without potatoes isn’t a full meal. Et cetera.
If you want to try it, I recommend doing it with one other person who you can commit to having dinner with every day (and spending enough time to plan and shop for those dinners) for roughly 2 weeks. My doctor didn’t think it was a good idea to frequently cycle on and off of keto.