When it comes to food, your day-to-day does NOT have to be the same in variety or amount, even if you're trying to lose weight. You've got to eat according to your plans for the day.
To give you an idea: my eating choices are for the most part quite premeditated. I eat according to my goal/schedule for the day. If I know I'm going to have a busy day of meetings, running around, or teaching, then I know I have to eat more for the right kind of energy to keep me going and alert.
If I plan to do one of my intense short workouts in the morning, then I'll eat a little more (carb) and good fats the night before to provide my body the best fuel for a quality workout. Then after, I'll make sure to get a little more protein that day to help my body recover after the workout.
If I know I'm going to have an easy day or may be sitting around on my butt for the most part, I'll lessen my food intake and try to keep portions small and clean.
However, if I should decide I want to eat whatever, or if an unexpected event takes place, no problem! I don't beat myself up. I just go with the flow. I will allow myself to enjoy (with mindful awareness), and I would plan to clean up my eating tomorrow; I could do a quick intense workout, or clean up my eating, or do both if I felt it was necessary.
I make an effort to be mindful of my actions (from what I eat, how I move, to what I think, say or do). I choose to make a conscious effort to restore balance and harmony in my body. This way of living for me did not happen overnight. I had to slowly rid of old habits that were not serving me well in order to get to a healthier lifestyle.
Maintaining a healthy weight requires a holistic approach that combines proper rest, good workouts, being mindful of when and what you eat, and how much; and take action when it's time to clean up your act.
If you take care of your body, it will take care of itself.