Yes, though it depends on when you start paying attention and how you define "intermittent". My intermittent varies from 8-16 hours per day and 1-3 days per week depending on autophagy and ketosis, both of which appear at ~ 48 hours for me but can go from 24-36 hours depending on exercise, i.e. there are risks in running long distances while fasting, but I have a daily carry kit that includes gels and fruits so I've not been to an emergency room in 30 years, which brings me to my next point.

Chronic Type 1 Diabetic here so the things I'm about to describe are high risk and are not endorsed by anyone in my world-class care team. They are aware that I understand and accept the risks having grown up and been educated at Children's Hospital and Joslin. I wear an insulin pump and two Continuous Glucose Monitors (CGM).

It's all about executive function. From a root cause perspective, I'd start there since that's really what determines health.

My fasting started 15 years ago when I read Seth Roberts Shangri La Diet.

https://en.wikipedia.org/wiki/Seth_Roberts

I'm one of those people who can balance empirical and phenomenological despite n-of-1 emergent qualities.

In 2007, I'd fast for 3 days liquid-only roughly once every 90 days. I used Roberts extra light olive oil hack (ELOO) to help. I don't do that anymore though it had no negative effects in my experience. I practiced that cadence until 2020.

In 2019, I stopped eating meat. I like meat but it was the easiest way to get the caloric load and impurities down. From fall 2019 to summer 2020 I lost 50 lbs. Ate plant-based whole foods for two years, then and now vegetarian. Over that time I've varied from 0MAD, 1MAD, and 2MAD while finishing a half and full marathon in 2021 and 2022, respectively. I run mostly daily, varying between 10K and 10 miles with occasional half marathon distances tossed in for good effect.

Post 2022, I've done a series of experiments with some success. Those include emulating Valter Longo's protocol with soup for a Fast-Mimicking Diet (FMD). Also, my current regimen has been eating M-W-F and fasting T-Th-Sat-Sun. I sustained that for a couple weeks and I'm eating once or twice daily now. I'll probably reverse the intermittent binge-ing in new experiments, so 4 days eat, 3 days fast per week; theme and variations.

I'll probably return to a odd-metered cadence of fast-feast weeks as it made meals much easier with the challenges you mention.

For whatever reason, I ate 5-6K calories/day from high school through college and couldn't fast a few hours. At my age now, fasting is easier than eating and could very well be related to delayed gastric emptying or some other complication of disease. I have no evidence.

The less I eat, the better I feel, while benefiting from the anecdotal improvement in cognitive function that comes with ketosis. Like leading ultramarathon runners, I don't practice ketosis as perfection, but rather, a state I hit occasionally without making it an end-goal. Paraphrasing Peter Attia, it's the cycle, not the state that matters.

The limiting factor for me is of course not ketosis, but ketoacidosis. The former is well-managed for me because it's predictable, euglycemic, and easy-to-fix with carbs. The latter was common enough to me as a young person that I know the ketosis flu feeling well and avoid it by testing compulsively. Just like software!

FWIW, I've vomited water in euglycemic ketosis and know enough to avoid the emergency room. This scares my medical team, since there are truly frightening and deadly side effects (refeeding syndrome), but I'm still here.

I've worked in medical devices and healthcare so my learning has been enhanced by those experiences where we treated patients who responded well to coaching around metabolic illness including cancer and diabetes, both of which respond to diet and fasting.