Intermittant fasting is something that comes naturally after reaching 100% fat adaptation, and shouldn’t be forced. I found my eating windows starting to shorten around month 4, and then had my first spontaneous 24 hour IF around month 6.
Have pondered this a bit, after taking in various insights from Dr. Atkins, Dr. Phinney, and the Drs. Eades all of whom have guidelines phases for higher carb levels for folks after the initial induction period - as well as Dr. Fung, who focuses mainly on reducing the eating window.
Fung has pointed to the fact that how often you eat is actually as important, if not more, than what exactly you eat - when it comes to reducing insulin spiking, the key factor in turning around obesity and diabetes. At some point, what you eat does matter of course, it’s just that there’s a huge difference between high refined carb/sugar intakes and low. He’s referred to how traditional Asian people typically eat only 1-2 meals a day within an 8 hour period which contains a bowl of rice or rice noodles - and don’t get obese. They may have other health issues due to high sugar drinks or alcohol or smoking, but obesity was mostly unheard of in Asia before industrial fast food hit.
Some fat-adapted LCHF/keto folks who eat 3 meals a day plus snacks may actually have more overall insulin spikes than someone who eats less meals and has a higher carb intake involving low glycemic carbs (basmati rice, sweet potato, etc).
I combine both Dr. Fung’s info and Drs Phinney, Volek, and Eades in my Intermittent Fasting serveral days a week plus keto eating.
Once you’re 100% fat-adapted, combining Intermittent Fasting with Keto can be very effective for speeding body recomposition in my experience, and testing it out to see what happens for you is important.
I’ve been delighted to find that enjoying all my daily carbs in an abundant way in a small eating window on an OMAD day (120grams total/60 net on occasion, but usualliy around 40-50net) mostly counting only the refined carbs/sugar and high glycemic ones - not counting veg fiber or erythritol carbs or yogurt fertmented lactose carbs - digests them quickly and is very satisfying and has not slowed my body recomposition.
On the other hand, I aim to fit in more protein via having two meals during the eating window several times a week. When I do that, I’m strategic by eating a very low carb first meal so that I can possibly enjoy a foodie dinner that contains wine plus a keto dessert. 