I monitor my daily intake of calories, salt and sugar. Normally I prefer to cook myself for lunch and dinner as I will then be able to control the amount of salt and sugar to be used.
I calculate the individual food calories so that every day intake will not exceed the amount I took the day before. This way, I will not likely to increase weight. At the same time, I take supplement like amino acids, protein, etc when I am doing weight strengthening exercises. This will help to maintain my muscle to be lean. So I will only gain muscle weight instead of fats.