[aenis]

TLDR: Long fasted cardio. No exogenous ketones needed.

My wife and I have the same dietary regime when we need to lose weight - but I exercise, and she does not. We do 0-calorie alternate day fasting + strict keto on the eating days. I do quite a bit of fasted cardio - I cycle to the office 3 days per week, on my fasting days, and thats 3x72km of cycling over hard terrain and usually in the wind.

I am around 6-9 mmol/l on fasting days and 3-4 mmol/l on keto days, and she - same diet, but no exercise - is around 1.5-2 mmol/l on fasting days and 0.5-1mmol/l on keto days. All measured around 6pm when our ketone bodies are usually at their highest levels.

We reach those levels at around 3-4 weeks of following the diet. (We use this diet every year in the autumn, to burn what we gained over the summer of beer, eating out and other indulgences).

A few other differences: - fasted cardio means I get to maintain high ketone body concentrations through the night and in the morning. I routinely get 5-6mmol/l at 7am following the fasting+cycling days. - fasted cardio makes me very satiated the following day; I eat a very small keto breakfast and can't stand the sight of food till the evening. I maintain high ketosis through the day and have no problem with energy levels. Weird. - i have very low blood sugar, at around 2-3mmol/l on the fasting+cycling days. First few days are hard, then it's getting easier and easier.

I did ADF and ADF+keto many times in my life, usually for 2-3 months, and it always works, but only when I added long, steady-state fasted cardio did I start to experience those very high levels of ketone body concentrations. It was very scary at first, but nothing bad happened.

For comparison, while doing a multi-day fast - the longest I did was 82 hours - I am reaching something like 3mmol/l and feel very miserable throughout (not physically, but mentally). Short fasts (36hr) and keto are significantly easier. Weight drops very, very quickly.

[theNJR]

I’m surprised to hear you feel mentally miserable on longer fasts. I (and many others) report intense mental clarity. For me, everything slows down and becomes bright and clear. It’s really pleasant. Are you taking magnesium and sodium?

I’m tempted to comment on your seasonal health swings, but to each their own.

[aenis]

I do take magnesium salts and salt, plus apple cider vinegar. The brain works fine during longer fasts, can confirm the 'clarity' thing, but I do not feel happy when I can't eat for a few days. Of course thats not hunger, just addiction to food. As to seasonal health swings, yeah, not great.

[BizarroLand]

I mean, they are cycling 72 kilometers while in a fasted state 3 days a week. I'm assuming that is roughly 2-3 hours of aerobic exercise at a very athletic pace. That would be a high level of exertion for a non-fasted person.

[smaddox]

Very interesting. Thanks for sharing!

[herrrk]

Thats freaking fascinating. Thanks!