This is true. This is a matter of discussion between paleo
diet shcolars, where some state the "lean meat" approach
that you refer to and others prefer a diet more high in
fats. It is an interesting fact that Eskimos were known to
discard a killed caribou if it was not fatty enough!!

 One should still take into consideration a few things:
 
 - Stone age man had to move their bodies so much more than
the average Western person does today.

 - Game was raised on grass food and much more trimmed from
freely moving around than today's factory farmed animals.

 - They did have certain periods where fatty animals
could not be caught for various reasons.

 One does not have to be scared of animal fat on a paleo
man diet. However, it would be naive not to exercise and just
blindly eat fat all the time for the above stated reasons.
Even  Dr. Atkins pointed that out in his books.

 Thank you for your post.

Thats interesting..and yes  the real life of a paleo man would have been calorie high..even in medieval times the average man ate 9000 calorie if he was in the fields etc and a paleo man would be very physical, but not every day. I would think the diet would alter to season, migrations and what you were doing just as in modern "cave men" societies.

However fat was and is important...due to the seasonality of produce and like bears and other large mammals we would need to stock up in fat reserves.

Very true..EAT ONLY ORGANIC meats and eggs. The modern reared animals are fat adn unhealthy and have all sorts of vaccinations and anti biotics in their systems. when you see the diference in the meat between an organic chicken and a barn intensive raised one its amazing. The meat colour is different and theres solid fat  not this running white stuff on the mdern hens have. An orgnic chick runs about and eats all kinds of stuff, and tastes better too.

The common broiler chicken is 50% fatter than 30 years ago and the eggs have lost 70% of their omega oils..its shocking ! and as you say fish have mercury and other nasties..unless farmed.

Also we cant possibly be as active as a paleo man or woman so eating fats like they did wouldnt be a clever thing to do if we have a sedentary life.

The veggie version and a little meat would be healthier for us modern cave people !! LOL unless you run to work and back and have a physical active job.

even in medieval times the average man ate 9000 calorie if he was in the fields etc

Do you have a source for that?  It seems high to me.  9000 kJ rather than 9000 kcalories, perhaps?

Actually, many types of farmed fish contain MORE mercury than wild, so that is absolutely NOT a good rule of thumb

Not only that, but some farmed fish - salmon for example - has a fat profile more like factory farmed beef than like the wild version of the fish.  Granted, that's still a lot better than most vegetable oils - or than factory farmed eggs, even, but for those who are really picky, there is a lot of information to digest, as you say.

Also in the US they still use ground up animal matter in the feed, and feed the animals on GM soya and other crops that we dont do in the UK ...The fat would only be of good quality if the animal has a lot of exercise anyhow and has a healthy liver and is OLDER than the birds or other animals we eat today, they are ALL forced with hormones.

I think we all need to go back to crofting to have a proper diet...and eat far more veggetales, greens, and berries as they would have done..I am in a flat (apartment) so cant do that but I advise any one with a back garden or yard to grow more...as ALL our fruit and veg is nuked before it gets to the shelves, and is irradiated.