As an approx 18 month long carnivore, I am drawn to eating nose to tail, for the variety, the nutrition, and out of respect for what I am eating. My Western squickability currently precludes me eating brawn, tripe and eyes. The rest is fair game. I eat roe (lumpfish, salmon and cod), marrow and add butter to compensate for lack of brawn.
The days I eat liver, I feel physically and emotionally better, but cannot pin down why.
Several consecutive days of eating liver and my appetite for it switches off.
Sorry, I know this is somewhat off topic, because this is a discussion of the science, not appetite.
However, before we had measuring scales, studies and names for the different minerals, we were all eating to appetite (and availability). I think we have some very deep instinctual guidance on nutrition - and that is going to vary from person to person, depending on age, food quality, and our own personal needs. Of course, the trick is to listen to it, and not obsess about numbers.
My question is whether people who ‘just eat muscle meat’ are listening to their own bodies? Or have they switched the volume down to zero because they are fixated on some ideal of dietary purity? Not for me to judge. The best indication is their long term health, and hopefully IF there are pitfalls and malnutrition, then they will identify and adapt before the damage is irreversible. If, after 20+ years they are still thriving, well, it obviously works for them.