> Trial and error led to eventually getting on the lion diet (only red meat. no veg, fruit, grain)

Of course, if one is subscribed to any or many of the various general anti-red-meat narratives, from environmental to medicinical, they won't be interested in taking this up anyway, so the below advices is for the others really, any potential quick-adopters.

It's a mighty fine regime but: for starters, this better be fatty red meats, not overly lean, since this WoE usually (by prescription or just general satiety dynamics of meat-to-satiation) tends to dial down carbs severely or cut them completely, and you want plenty of your 2X00 kcal / day to come from not proteins but either fats or (if you still think them desirable or necessary after a while) carbs, and trust me you'll soon-enough rather gobble extra helpings of butter or yolks (or the copious meat fats that usually get trimmed off) than drink tablespoons of oils.. burning proteins for fuel energy is an emergency measure, they're not an ideal "calorie source for burning". (Search terms: "protein poisoning" or "rabbit starvation" in the absence/lowness of both carbs and fats.)

The second caveat is that pork is generally categorized as red-meat just like the ruminant kinds (in the modern world, beef and lamb, but everywhere humans evolved had their own variants, whether gazelles or caribou) but while I can vouch for years of daily satisfaction with a ruminant-meat+butter+eggs setup with no sense of lack or deficiency, I somehow deep down wouldn't trust the non-ruminant, only-so-labelled "red meat" of pork to deliver a like track record (and I have no cultural/religious imperative to be either halal or kosher). I like me a good piece of salami or bacon every once in a blue moon just fine, but the "lion diet" or sustainable human carnivory regime isn't about thriving-on-cold-cuts-and-pork-chops, without even having tried I think that quite impossible.

The third reminder is to mind nutrition completeness: fresh fatty ruminant meat and soft-boiled / sunny-side-up eggs (ie. with runny yolks but cooked whites) are "nutritionally complete" as far as a human cares (ignoring the modern notion of roughage aka "fiber" as some sort of nutrient, what's by-definition undigestable/unabsorbable is not simultaneously nutritive as-in nourishing). BUT processed meats incl. cured / smoked hams, sausages, patés and all that jazz aren't, neither is a roast that has been baking away in the oven for 2+ hours. Slightly pink and still-quite-juicy and you're good for sure. Whether that's steak or just mince. (And for that aspect, another good reason to emphasize ruminants over pork, fowl or seafoods. Doesn't mean the latter are taboo or "bad food", just perhaps in-the-long-run not "the staple" for max well-being.)

So to sum up: 1. ensure sufficient non-protein kcal inputs still (I can only speak for animal fats myself), 2. mostly-ruminants is likely superior on a basically-meat-only regimen, 3. for full nutrition ensure absolute dominance of fresh-not-processed meats and of rare-or-medium-rather-than-over-cooked meat.

Also, listen to appetite and fullness signals much more alertly and trust them. There'll be days of gorging and feasting as well as lean days this way, but they're directed by something better informed about your body than current science: namely, your body.