Follow-up to: Boring Advice Repository
Many practical problems in instrumental rationality appear to be wide open. Two I've been annoyed by recently are "what should I eat?" and "how should I exercise?" However, some appear to be more or less solved. For example, various mnemonic techniques like memory palaces, along with spaced repetition, seem to more or less solve the problem of memorization.
I would like people to use this thread to post other examples of solved problems in instrumental rationality. I'm pretty sure you all collectively know good examples; there's a comment I can't find from a user who said something like "taking a flattering photograph of yourself is a solved problem," and it's likely that there are other useful examples like this that aren't common knowledge. Err on the side of posting solutions which may not be universal but are still likely to be helpful to many people.
(This thread is allowed to not be boring! Go wild!)
As far as I can tell, ketogenic diets solve the problem of fat loss. I know, anecdotes are not data, but it's worked wonders for everyone I know who's tried it (myself included).
This is the sole reason I'm posting this. Keto works for very many people. The short story of keto is that your brain can only eat certain kinds of chemicals. Glycogen from eating carbohydrates is one of them. Ketones generated from fat is another. Your body will preferentially use the first over the second, since turning fat into ketones is expensive. So if you eat few enough carbs (<30g per day is the figure I remember) and plenty enough fat (2:1 fat to protein is what I heard), your body will eventually start doing chemistry that turns dietary and body fat into ketones.
There's some more practical advice about how to induce ketosis quickly (muscles store glycogen, so exercise helps) and how to make low-carb versions of foods you enjoy, but that's pretty much the gist of it.
What do you think of the research described at https://slimemoldtimemold.com/tag/a-chemical-hunger/ regarding lithium?