Thanks for posting this, @atomicspacebunny. I have a lot of respect for Penn Jillette, even if he and I come at life from distinctly different perspectives. I’m bookmarking this for later perusal.
Tangentially, I had the pleasure of sharing a gym with him way back when I worked in NYC and we both were larger men. It was always a fanboy treat to bump into him.
But is it really keeping her healthy? I recently watched the video below that uses forensics to determine the health of agriculturalists vs hunter/gatherers. The agriculturalists died younger, had 700% more cavities, died more often in childbirth and had more issues with their bones. Skip to 27:00 if you want to watch where he compares two ancient societies that had vastly different diets and zero processed foods were involved:
As I like to soapbox about, everything is case by case or should be. EVERYthing.
Those in medicine -the smarter ones- know this.
In my own family -just an anecdote- I have a lifelong, never had meat not once, vegetarian, now 7yr vegan daughter who just had her 3rd (and 2nd effortless home delivery) kid in 5 years, she’s 35y/o, stayed vegan for all pregnancies and long lactations and looks like a fitness model. I am not kidding. Her muscle tone is enviable, she does NO WORKOUTS (though is active w/kids and two big dogs), her energy and general health, ditto.
When I was pg I had to eat tons o’ meat. Tons. Otherwise I felt like crap. I was vegetarian for 8 years (animal advocacy reasons) and never felt well. I need animal protein, actual meat, to function optimally.
I have seen more cases than I can count in my decades old career in medical genetics, of idiosyncratic responses, symptoms misaligning w/hard data, tx being tailored to suit what flies in the face of protocol, and getting good result.
No one diet works for all. Individual biochem is not measurable therefore overlooked and underconsidered.
If you can get the essential amino and fatty acids from plant proteins, possibly combined with supplements, then it is possible to be in nutritional ketosis on a plant-only diet and remain healthy.
The other point to bear in mind is the success of the Kempner rice diet (Denise Minger has a lecture on it on YouTube), which involved eating a lot of carbohydrate and even sugar. It reversed many people’s Type II diabetes and promoted fat loss. The key to this diet was extremely low fat intake, just as the key to a ketogenic diet is extremely low carbohydrate intake.
This applies to my abovementioned daughter. She eats almost no fats.
Another v odd case I posted about in another thread of my pal who is aged 56, 5’11" weighs 140-145, wiry build, not much muscle definition though, brilliant programmer with severe ADHD. ZERO health probs (is a kinda hypochondriac so sees doc regularly), is an extreme hiker as in travels internationally to hike (went to NZ, Peru just last year alone for hiking), is NEVER STILL, hyper to an annoying af degree and whose diet consists 90% processed carbs and HIGH sugar, drinks only Mountain Dew, occasional burger but little meat.
He is strong as a freaking team o’oxen. I’ve watched him lift/carry heavy ass car parts (he rebuilds classic cars as a hobby), building materials (he builds his own houses too), tree trunks after cutting trees, his strength and endurance both are freakish. He looks like a weakling.
Has had the same doc for decades who tells him “it’s obviously working for you” regarding his horrendous diet.
He is a mutant. I in no way think his case would be extrapolative to many others BUT he is a good example of everything is case by case.
Extreme caloric restrction is part of it. Another part is limiting the intake of fat which does (at least) two things. They are both rather complicated and I’m less than good at trying to explain them.
Warning: rabbit holes ahead 
And then there’s this:
Bon appetit!
I think you can eat a boatload of leafy green vegetables, and Cuciferous vegetables, and proteins and lose weight. I think it’s more about what he didn’t eat and what he did eat.
I have some relatives in a number of friends who weigh what they did in high school and they eat vegetables and low fat and very little meat. It’s frustrating to me being a bit of a fatty to be trying this carnivore/keto diet and losing weight so slowly. I look at this and say Gee should I be eating vegetables and low-fat? I’ve read all the books, and I see that we are largely not meant to be eating only vegetables. Additionally if you look at our physiology we are clearly not vegetarians.
I’m looking at this potato diet and I’m wondering if some of it has to do with the resistant starch created by cooking and cooling potatoes, particularly when you’re buying it in a container and rehydrating it. I can almost not swallow a dry potato, I would certainly not eat very much, although potatoes are very satiating. Of course, I always like to potatoes with sour cream and bacon and chives and butter … lots of butter. If I can’t eat potatoes with the these items why would I want to eat potatoes?
There’s very little resistant starch in potatoes after heating and cooling. You’re still getting quite a dose of carbs.
I read his book about his diet experience, and decided I couldn’t not do it that way. Cold showers and the crazy eating routine was something I wasn’t going to be doing. I kept searching and found keto, the rest is history for me. He was very honest about the hunger involved and he couldn’t do a show one night because he passed out.
I think some would be ok with it, just wasn’t for me. When I was in my teens and twenties, vegetarian diet did keep me thin, but I was sick a lot, wasn’t willing to risk going back to that at my current age. I like feeling years younger than my age.
I know nothing about his method except THIS^^^ kinda indicates he will fail to sustain; sounds like a case of Biggest Loser style.
I add that it suggests that “eat whatever he wants” is hyperbole-too-far, to the point of, well, lying?
When you look at the picture of Penn he has both legs in one pant leg with enough gap space to do a small dance; that is dam near a miracle in and of itself, that tells me what he did is similar to Dr. Fung’s take on limiting protein intake and fasting where the skin is catabolized evenly with the loss of body fat, if he had of tried this any other way he would have been looking at bariatric grade surgery with a lot of loose skin hanging of his bones. So if you want to tighten up the birthday suit, cut the protein down, cycle it or cut it out completely on a temporary basis until you reach your body shaping goal not just burning body fat, quite a few people can’t figure why they got all this loose skin after going keto?
I like the idea of combining seasonal ways of eating which some people on the forum and else where do this also?
This is so fascinating to me!
Denise Longer also has an article in which she states that we can be either high fat OR high carb. But we cannot be in the.middle, doing “moderation” eating.
OK this may account for my two oddball examples above. Neither of the two (VERY different diets but both very high carb) eat much fat at all; my daughter prob only what’s used to saute/cook with and Mutant Pal, none added at all as he NEVER, ever cooks, hates restaurants and eats only from packages. He does eat large amts of chocolate though. Interesting as heck.
Her articles are mad.long, but she details Every Thing. She talks about groups of tribal people’s who live on very high carb diets and how it works for them. And she contrasts them with other groups, ie: traditional Inuit, who eat very high fat diets. Both groups are super healthy.
It intrigued me as I once did a very low fat diet a la Susan Powter for maybe a year. Lost maybe 10 lbs 
This is really interesting, when I went Vegan (pre-Keto), I had a brief period of quick weight loss, however as soon as I started adding coconut oils and tahini and other “healthy fats”, the weight loss stopped completely and I was only consuming 600-800 calories a day tops. Regarding my personal experience, I could see that it really is high carb + super low fat that can work for some OR high fat + super low carb for others.
