Ultimately, the thing that matters is calories. By eating strictly lowcarb we can eat more calories (since our body doesn't use calories from fat as efficiently as calories from carbs) and we can control cravings since our blood sugar stays stable. However, even with the extra carbs in the evening you must have been eating few enough calories that you were able to lose weight -- probably because you weren't eating any junk food during the rest of the day. You're not very overweight at 5'7" and 160 pounds, so you probably don't have as many problems from carbohydrates as some of the rest of us do. You may well be able to continue what you are doing through another 10 pounds or so. My guess is, however, that to get to your goal weight you are going to have to get very strict with your eating for the last 10 or 15 pounds.