Assuming a sedentary lifestyle, would it seem to be much more difficult to fast (esp longer fasts) on a high carb diet? Because of insulin spikes and drops?
Low carb first for a while, then fasting in that order. For me it was almost effortless.
When I was young in college in the early 80s (for context) I didn’t even know about low carb. I ate everything but limited myself to one meal a day, dinner. I don’t remember having too much trouble with it. Could have been because I was young.
I’m still pretty active but metabolism slows down with age. Been low carb about 7 years now, IF for at least 4. It’s got to the point where eating is chore. I just don’t get hungry. I need to maintain calories for several reasons.
If you are looking to lose weight, I would recommend mixing it up a bit as far as eating schedules. Fasting should be an anomaly, not the norm. If the body gets used to it, it will adjust metabolism regardless. Thomas Delauer on Youtube talks about this and it kind of makes sense.
I think the main difference is in the first few days. High carb dieters will go through carb withdrawal, get really hungry, and feel very lethargic after a few days. But then they’ll adapt eventually. Whereas someone on keto, or just general fat adaption from OMAD or ADF for example, will generally cruise through the first few days with much milder symptoms. Then after a week, I don’t believe there’ll really be any difference. That’s my experience at least.
I’ve done high carb into extended fasts (I actually fasted for two weeks on a cross-country trip on my bike. Fun fact) quite a few times and am currently doing shorter fasts alternating with a few keto days. High carb crash a few days into a fast is miserable. So far, keto into a fast has had absolutely zero drawbacks other than the usual blood pressure drop. The entire reason I started doing rolling fasts instead of one long fast is actually because I’m trying to keep my blood pressure from hitting the usual low 5+ days in. 35 degrees heading to/from work, there’s a ridiculous difference between normal and lower BP. One is chilly fingers by the time you get home, the other is feeling like your fingers are frozen just a few miles down the road