how long would it take someone approximately to reach a state of ketosis after carbing up the night before and fasting the following day.
for example: last night I consumed 250g carbs around 10pm, slept until 8am. that's 10 hours of fasting. say i extended this until 2pm that would equal 16 hours of fasting.
would this be enough for a lot of people (if keto adapted) to re enter ketosis after the above mentioned glyocgen restoration of a couple hundred grams of carbs?
Based on personal experience, I would guess no. Whenever I carb up and go for about a 16h fast after, I don't get back into ketosis. This definitely depends how fat adapted one is however.
I know that when I do this except eating closer to 4 or 5 pm, plus 1 spoonful of coconut oil about 11am, I get back into ketosis every time.
Going into ketosis is different for everyone and depends on the person, how often they go into keto, and regular eating habits. Some could do it in under 48 hours, others it may take 5 days!
Keep your IF and I agree, I would eat a little coconut oil around noon and with under 50g of carbs (this again depends on the person), you could be there the following day.
You can do it, but it won't be as effective as with exercise. Your liver and muscles are stores for glycogen. If you don't work out, your muscles remain somewhat insulin resistant. Once you work out and deplete them of glycogen, they'll start to switch to burning ketones (until you eat carbs again.)
The path to quicker ketosis is working out with heavy weights and/or HIIT. Also, note that the larger you build your muscles, the more glucose they can safely dispose of, and the less fat you'll become.
If you want to kick start ketosis, you can ingest some MCT oil, or coconut oil. The MCT oil (about half of the fat in coconut oil) will be converted by your liver to ketones. While this is probably not ideal, as you'll want to burn your own fat stores instead, it can train your muscle mitochondria to start burning fats and ketones if you're not already fat adapted.
250g of carbs is quite a bit, usually I'd aim for 100g or less if you're not working out. Be sure to ingest enough protein for your lean body mass as well as you'll need it for gluconeogenesis and repairs. Going higher carb is fine if you work out to the point of depleting muscle glycogen stores and are doing a refeed, otherwise, you're somewhat over the threshhold.
Typical IF windows are 16 hours fasted, 8 hours feast. 10 hours is a bit short of getting the benefits of autophagy. YMMV, of course, but if you want to be absolutely sure, get a ketone blood test - they're expensive but much more accurate than ketostix.