I used to be just like that LOL. I lost 40 lbs in 6 months in 2011 after joining this forum. Initially eating the identical food everyday but also over trained. I purchased a smaller clothes and discarded or donated my fatty pants so when I do gain a few pounds, I feel it in my clothes. I refuse to buy a larger size. Call me stubborn.

Now I just try to eat cleaner. Egg whites, chicken and fish and when gain a few pounds, it's time to pull out the scales and track in my fitness pal. Before I go on vacation, I loose 5 lbs so I am not so crazy about macros when I am traveling.
Being consistent is best. I used to gain and loose same 20 lbs. I think you are more disciplined then I am in this moment. I will be back to measuring and tracking in a couple weeks. New cut coming up!