Everyone I know who is on a carnivore diet has a high enough fat:protein ratio to stay in ketosis most of/all the time. The value of that seems to be pretty common wisdom among carnivores.
It is possible, I have done it myself eating a lot of eggs and fatty red meat. Also, in my case I was also already in ketosis for an extended period of time, meaning my microbiome and cells were primed for ketosis.
That said I have also done carnivore and also not been in ketosis, which I think is probably the norm for most people on carnivore because the protein/fat ratios aren't right.
The commonality in ketosis carnivore and non-ketosis carnivore is removal of refined sugar/carbs which means no insulin spikes, which means steady levels of energy without crashing.
Meat also raises insulin, much less than carbs, but on a carnivore diet I can imagine this to happen.
The keto diet with ratios has been designed as a diet for epileptics, so in a ratio that maintains both body weight in a healthy range and induces ketosis and avoids ceizures (note: 1920s medicine or something). So the high fat content kind of is there to actually give you the energy so that you don't loose weight.
One aspect of the "carnivore" diet that is often overlooked, a "human carnivore in the stone age" will not have lived off of chicken breast and lean beef cuts, but easten the entire animal, i.e. the fat cuts as well that are surprisingly hard to get in a western country.
1) That's per 250 kcal. A plate of pasta has significantly fewer calories than a plate of steak. Sauces on either can alter this, but they'll likely have their own indices to pay attention to.
2) The low ends are equal. The high ends are off by a factor of 1.5.
I think that the real question is "What will happen to my insulin if I eat a meal of pasta vs, a meal of steak?". To that, I think that the steak will in fact spike your insulin much higher than the pasta.
That said the beef has a higher satiety score (by almost exactly the same ratio as the high end insulin ratio).
Again, sauces, what your body needs right now, what you'll eat for your next meal,... lots of things can alter the overall health perspective.
This also depends on eating frequency. If someone has a very low eating frequency, like a single meal every 72 hours, even a meal of lean meat may not knock a person out of ketosis, at least for very long. I've fasted that long and eaten a huge meal of lean meat, multiple times, and my keto testing strips always remain dark purple.
As much as I think keto and carnivore are lightyears past the average American's diet, I've found them difficult to maintain because they're very restrictive and I lack the energy to be effective when working out, which is common. Fasting in combination with a low carb diet, even one that incorporates things like berries, has been much more effective and easy to maintain in my experience. Combining macronutrition with eating frequency reduces the penalty of eating carbs or lots of protein by making it much easier to get back into ketosis. When you force your body to burn through its glycogen stores, and you give it no choice but to use your fat store, ketosis will come back in no time.
So you are definitely correct that fatty cuts are better, most of the time, but with fasting the protein to fat ratio almost becomes a non-issue.
