I used to go out for lunch, and I was spending about $50 a week, not counting weekends.
I need to reduce expenses as much as I can now though. Luckily, I only live about two miles from work so I go home every day. I can buy a can of Chunky soup or chili for about $3, and that is about the most expensive thing I eat now.
Otherwise, I make sandwiches (pb&j, egg salad, tuna, spam salad, grilled cheese), with or without condensed soup, crackers, chips, or raw vegetables, and just water to drink.
I've already started losing weight. People don't realize how many calories plus other crap is in those fast food (or even restaurant) meals, not to mention sodas.
Plus, now I can watch TV while I eat, rather than just sitting in a restaurant or staring at my computer at work.