I’m a 7-year ketonian who randomly decided to fast for 3 days. At day three I told myself that I’d keep going until I felt bad. I’m now on day 7 and feel great, so I’m going to continue.
Is there anything I should be aware of for fasts that lasts longer than 7 days? I’m on top of my electrolytes and water intake, but what do you do in terms of micronutrients and supporting your microbiome?
If you’re a healthy person that isn’t deficient in any nutrient already and isn’t coming off another recent long fast, the only thing you’ll truly need to supplement on a 7-day fast is electrolytes. I think many people might deplete one or more of the water-soluble vitamins on a longer fast, even if they’re healthy at the start of the fast. Your body has a large store of fat-soluble nutrients in your adipose tissue and micro-elements in your bones, so those shouldn’t be an issue as long as you aren’t already deficient. And there’s not much point in supplementing a fat-soluble vitamin or something like selenium anyways unless you’re eating a meal with it, because absorption will be garbage. Of course, there’s no telling without bloodwork and medical monitoring during your fast.
For fasts longer than 3 days, I generally just take a daily B-complex tablet (includes every water-soluble vitamin) as insurance, in case I happen to already be low in one or more of them. Mild B deficiencies can cause fatigue and brain fog, and I figure a single pill a day is worth it, absorption is decent since the nutrients are mostly absorbed fine in isolation just dissolved in water, and it’s relatively difficult to overdose on water-soluble vitamins because the excess just gets excreted in urine. Probably no real harm in not taking it, either.
As far as your microbiome, the organisms’ populations will drop and they will generally subsist on the small amount of matter that remains in your digestive tract and/or will go into a kind of stasis. This will naturally reverse once food becomes available again. There’s really nothing to be done to change this besides eating.
The best advice other than being monitored by a physician knowledgeable in fasting would be to stop if you begin feeling bad.