Short time periods being the operative phrase. Judging by observation, I'd say things work best when you have a range of intakes. Carb cycling for diet is, of course, well known. I think the same thing applies if you want to get big- not just carbs, but proteins and fats as well. Also if you vary the sources of these. I used to be a very dogmatic eater until actual experience made me realize that much like shocking your muscle for actual growth, the same can be done with your nutritional uptake. I realize you can't correlate involuntary/voluntary systems, but I've noticed worthwhile improvement. I don't know if the same holds true for everyone, but it works for me and makes eating more fun.