I developed ulcerative colitis and had to stop eating grains, other starches and sugar, since they make me much sicker. I also had to give up most vegetables, but hopefully that is temporary. I had stopped eating meat years ago, but added fish, poultry and eggs to my meals. My primary fat source is nut butter. Now after 4 months I'm feeling much better and I've lost the 15 pounds that I attributed to middle age. I run and lift weights and can't say that the change in diet has made either harder. My long run at this time is only about 8 miles, so I can't claim to have the nutritional needs of an endurance athlete. I can tolerate a small amount of white rice, so I'm using that to support the running. When I was younger I did sucessfully compete in power-lifting and agree that the amount of protein consumed by the average guy in the gym may be excessive. Before getting sick I would not have wanted to change to this sort of diet!
Hopefully I will figure out this diet as an Orthodox before Great Lent arrives, any good advice?
We had a separate thread about how to eat this way during fasts but we can take this up here too.
The trick is to keep your fat intake up. Since we cant eat butter ( though I have not heard of Nut Butter but it sounds Lenten) I suggest Coconut Oil. While you can certainly use it to cook with, I think that is not enough to satiate your hunger during fasts.
I make it into a tea. Boil a cup of water and add a large tablespoon of coconut oil and then drink it down.. Yes it's a greasy solution that is borderline disagreeable but you will get used to it. I would drink this three times per day before regular meals. At the minimum once per day.
Your hunger should be under control if you do this. Then lots of leafy vegetables cooked or raw, some fruit, salads, and all the lenten seafood you can eat without getting sick of it (Shrimp, Calamari, etc). There is also a product called "Quorn" which is a mushroom that they fashion into ersatz chicken patties and similar, like they do with soy ( I would stay clear of soy). It is a great protein substitute and pretty tasty.
And to drink, Almond Milk or even better Coconut Milk which is now available at most groceries these days.
There is also stuff like Almond Flour that you can make into pancakes and also No Carb Bread made from Almond or Coconut flour that you can get online. A slice of No Carb bread with a smear of your Nut Butter sounds like a winner.