Lots of people have, let's say, interesting nutritional habits.
To each his or her own, I guess. Luckily for me, nutrition gives me little joy - unless beer is nutrition. (One thing that gives me joy is leaving the damn gym after a workout.) I'm not skinny, but fit for age. Wait - that's a lie because I do enjoy a few slices of a rare ribeye.
Zero carb eating is not especially about losing fat (altho it works for that). Jordan Peterson only consumes steak and bubbly water for some wacky reason. Lex said he is sort-of similar. Whatever, but they should do a daily or weekly multivit. That's fine despite being a little idiosyncratic.
Fortunately, we have learned that dietary fat is harmless, and also necessary.
Lots of people find too much eating makes them less sharp and more lazy. I'm like that. My trainer, who pushes me to eat more, always notices that I am stronger after a day without food, like, after some GI problem.
My nutrition has been mainly Thai take-out lately. Convenient. One $11 take-out meal is 2-3 meals for me. I tend to eat once or twice daily, not by discipline but for lack of interest and because food makes me tired. I am also a very slow eater and tend to stop the minute any hunger goes away.
So people are different, but food is not medicine. Again, not talking about getting rid of surplus body fat even though that's a good idea for life fitness and vanity.
Is a No-Carb Diet Safe? One Dietitian Discusses the Pros and Cons