Do you want to save money, don't eat in restaurants every meal, and if you do, eat Breakfast, it is the cheaper meal.
During the day, I go to the markets and shop, just yesterday here in Lima, Peru I entered this huge super market and purchased some Bananas, Apples, Bread, Butter and Cheese. Later in the day, I cooked a Cheese Sandwich for Dinner. I spend every day purchasing food for my dinner, and in the morning, I go to Breakfast.
If go to Dinner, it is normally because I am with other people and want to socialize, however when I am alone, I eat in the Hotel.
I am in a Hotel presently that has a guest kitchen, this make cooking at home easy. PrettyHousePeru.com, a truly great family ran Hotel in the Jesus Maria area of Lima for 50 Soles per night.