The biggest thing I have realized when it comes to staying on the slim side, is that portion control plays a big part. Aside from healthy eating of course. I used to eat until I was stuffed to the brim. I thought since it was a clean meal then it was okay. After doing this for some time, I realized I wasn't really leaning out like I wanted to. Now I just eat until I am satisfied. There really is no reason to eat to where you have to unbutton your pants. Your tummy just needs to say, "Yep, that's good right there. I'm done."
I started eating smaller portions and started leaning out. Portion size is huge in this process. This chart provides a great visual for how much to eat of what. Try it out!