Wow, IF and giving up carbs, sugar, and salt sounds like a lot to me. I eat one meal a day at lunch and skip breakfast and dinner, but I didn’t just jump into OMAD.
Maybe you could go a little slower with the fasting, eating your regular breakfast, lunch, and dinner with no snacking at first, then either move breakfast later by 30 minutes every few days and/or make dinner earlier by 30 minutes every few days. The trick will be to only move the time when you are ready. You might also want to try more keto-friendly foods (meat and veggies) at the start of your meals and carb snack food like triscuits as a dessert at the end of the meal if you actually have any room.
I would say to cut out snacking if you can. You have to train your body to know that it doesn’t have to constantly eat.
Maybe don’t cut salt yet since it is important for fasting, but leave carbs for dessert and keep them small. Stop snack snacking on carbs, if you need to train your body to stop snacking, switch to keto friendly snacks at first (cheese, nuts, hard boiled egg…)
Anyway, that would be my suggestion. Good luck and happy fasting!
This isn’t a popular opinion, but if you try other things and they still don’t work, I highly recommend giving up caffeine. It will suck at first, but can be so worth it in the long run. If you are waking up around 7 and having coffee soon after that, it totally makes sense that you are crashing at 11.
When I first did keto a few years ago, I was working as an early AM DJ, generally waking up at 4:45 or so. I’d start drinking coffee around 6 when my show started, but by the time it ended at 10, nothing could keep me awake and I had to take a nap. I cut the morning coffee and haven’t looked back.
At this point, I’ve had to cut caffeine all together. It’s a little bit too good at helping with appetite suppression for me and now causes lots of anxiety. Most people are not that sensitive to it, but it’s definitely something to examine if you are having energy problems.
Have you played with start and stop times? Maybe you need to start earlier and end earlier. Have you journaled when you have energy dips? Have you had a blood work up… are you getting enough sleep (do you need a cpap?)? No judgements… just some thoughts…
How long have you been making these diet changes? I’m assuming only a few days? If it’s already been longer than a couple of weeks, then disregard my advice below and talk with your doctor again, because you should be past any “adjustment period.”
If you’ve cut out sugar and carbs, you are likely going through a “keto flu” type of thing. That’s likely causing your exhaustion more than IF. There are two ways out: either push through until your body adapts (a week or two), or reintroduce carbs. It’s completely up to you (and your doctor). I don’t do keto (I just try to keep starch and sugar reasonably low), but many here do. It’s a valid choice either way.
Your 16:8 IF schedule is very reasonable — generally it is recommended as a good way to start IF. There still can be an adjustment period of a week or two, as your body adjusts to your new eating patterns. But this sounds pretty extreme, beyond the normal amount of feeling “off” as you adjust.
Often, fatigue, nausea, and headaches can be related to low electrolytes (sodium, potassium, magnesium). Ask your doctor about this if they told you to avoid salt. Usually the remedy is to put a little salt and potassium-based salt substitute in a glass of water, and drink it with a magnesium citrate capsule. But if you’re meant to avoid salt, that obviously might not work for you — ask your doctor.
Some people do better easing into IF with a 14:10 fast for a week or so then start adding an hour more once you are comfortable to work your way up to more fasting hours, 16:8, 18:6 etc. You need to do what works for your body & schedule. If you hate it, feel awful you will not stick to the lifestyle and get the longterm benefits.