First, try just 1-2 days but remove all caffeine/sugar like a week ahead. Once you can do 1-2 days without any major problems, try doing 3 days (Friday + weekend). Once you are fine with that, try 5-7 days, water + electrolytes only, no food, no juice; drink however as much as you want, if you feel weird, drink more (always with electrolytes). If something really feels off, have some energy bars ready to intervene and break fast quickly and safely. Also, check yourself for diagnoses that might respond badly to fasting and in that case avoid doing it.

Thank you for this. Can you comment as to why you think it's necessary to remove all caffeine and sugar in advance? The reason I ask is that I have a penchant for black coffee and imagine that it's useful as an appetite suppressant.

Because you might have nasty withdrawal effects like strong headache on the first evening that could persuade you to break the fast immediately. You can gradually tone down your coffee intake so that at the beginning of the fast you won't have those effects.

Can you safely fast if you rely on medication?

Discuss this with your physician. People who have e.g. problems with kidneys should not fast.

I've only done 3-days and not 7, but for n=1:

- make sure to consume salt (adding to water is the easiest); if anything, err on the side of both too much water, and too much salt (we normally consume a lot of both through food).

- Some people still consume certain zero-calorie items, like black coffee, green tea, or bone broth. You still get most of the fasting benefits, and it might be a good way to start (bone broth with added salt is a great way to keep electrolytes up, and fill your stomach).

- I experienced a bit of back pain; apparently muscle pains are common, especially with new fasters. Accounts vary on this being evidence of "detox", or a side effect of mineral deficiency; but supplementing minerals in water probably couldn't hurt.

- Dr. Jason Fung is a great resource: https://www.youtube.com/watch?v=tIuj-oMN-Fk

- You'll find it odd that you don't know what to do during mealtimes. :) Have a plan for another way to take a break during lunchtime, etc.

- Optional: it's vastly easier if you start already in ketosis (IF and/or low-carb)

Bone broth has calories.