[jrgoj]

The author went through keto flu, which is a series uncomfortable adjustments your body makes as it transitions from glucose fuel to ketone fuel (ketosis). People who begin ketogenic diets know this well. Fasting feels very similar. The most acute symptom is often "brain fog", which manifests exactly how the author described.

Ketosis takes several days to begin while the body burns through its reserves of glycogen, at which point the symptoms begin, then lasts several days while basic adaptation takes place. Full adaptation to match one's athletic performance while glycogen fueled can take months.

The author didn't even mention the words ketosis nor ketones, so I have to imagine she went into this quite blindly. Once you've gone in and out of ketosis several times, you don't experience flu symptoms nearly as much and sometimes (me) not at all.

For most people a fast starts to feel magical after about day 5, where keto adaption has taken place and the mental habit and craving for food starts to subside. Obviously this will vary from person to person, so maybe the author didn't quite get far enough along to get out of the woods, so to speak.

[buserror]

Strange, I feel that by day 3, I'm fully switched over, and in fact I get a bit of a mental boost; I'm /definitely/ sharper on day 3+four, and then it tails off.

Mind you my typical fast starts on sunday after supper, and finished most fo the time on friday before supper. I do that so it doesn't impact too much the social life etc...

Overall I don't recommend short fast. I feel you need at least 3 days for it to be worth it, otherwise you get the pain (hunger on the first day) without a lot of the benefits.

But then again I only have my own experience on tap; most people I know think I'm bonkers to stop eating for most of a week ;-)

[imglorp]

I describe that as a carb hangover.

In fact, if you're eating a regular Western diet and feel faint before lunch and sluggish after, you can appreciate to what degree you're chasing your blood sugar around.

Switching to a diet with more protein and vegetables, and maybe "slow carbs" ala Tim Ferriss, you can even those highs and lows out and not feel them any more.

[amelius]

I've seen some exogenous ketones products, e.g. [1]. Could these help to get into ketosis without the nasty side-effects?

[1] https://www.amazon.com/KetoSports-KetoCaNa-Original-Exogenou...

[binarypaean]

The belief is "yes" but research on the topic is new and unfinished. Dr. D'Agostino specializes in ketogenic nutrition, and discusses exogenous ketones for exactly that purpose in two podcasts[1][2].

http://fourhourworkweek.com/2015/11/03/dominic-dagostino/ http://fourhourworkweek.com/2016/07/06/dom-dagostino-part-2/

[vanderZwan]

> so I have to imagine she went into this quite blindly

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