I do egg and meat fasts in fits and spurts and I don't think I could tell you how long my longest one was since meat and eggs are the primary components of my diet. Cheese is the only non-meat/egg thing I'll notice I'm purposefully avoiding. When I'm eating 100% on plan, I'll only eat salads when we go out to dinner (typically 1x to 3x per week). Right now I'm on my third day of that. Probably the longest I've ever given up dairy is about 2 weeks. And During those times, I may have eaten a salad or some veggies if we went out to dinner. Who knows?

Cutting out dairy is good for about 2 to 3 pounds on me. It might be what you have going on?

Chef Ron - This is one of those things that seems to be individual. I find any fiber makes me retain water, but not fat, but with all that water hanging on, the scale will not go down, and it may even go up! The other thing is that I find artificial sweeteners, while not causing me to gain weight, don't allow me to lose weight either. And they give me cravings. I'm better off sticking to meat. YMMV.