Let me address the constipation issue. I think Im familiar with that. When Ive gone on diets that are atkins-like with hi protein and nothing else, I know exactly what youre talking about... Even with some greens there isnt much difference. Going number 2 becomes an exhausting painful experience.. I think its simply a matter of bulk in the diet. I would recommend you going to walmart, buying a container of 'Konsyl' psyllium husk.. Its like metamucil but better. Eat some of this at every meal.. If youre going to eat mashed potatoes, mix this in, etc. And you should find in a couple days no more cement painful like experience.
Also, if you stick to higher fiber foods like sweet potatoes or cruciferous, this also will never happen..