I just try to correlate my higher carb days with my heavy lifting days. High carb for me is 150 grams, since I normally float anywhere from 20 to 60 grams a day, and im just kind of a smaller person. I have no idea if this is right for you, but thats just what has felt natural for me. I'm a big yam eater, so most of the higher carb days are fueled with a japanese yam(s), or sweet potatoes, banana, lotsa asparagus, etc and lower emphasis on fat. Then my lower carb days have a higher emphasis on fat. I usually do longer low-impact movement like jogging or short interval training in the morning on the low carb days, to capitilze on fat burning. The high carb days are when Im usually in the gym.