Conventional wisdom is that you should pack your lunch from home to save money. I've never done this. There are enough lunch options near my office that I've always just gone out and bought whatever I happened to be craving every particular day.
However, I've been working from home since April, so I'm not buying lunches, and I think I'm spending slightly more money.
I don't keep track of money super closely, but I know that I typically use cash for groceries, household and personal care items, and buying my lunch when I'm at work. I always withdraw the same amount when I go to an ATM, and I find I'm going to an ATM an average of one more time a month since I started working at home, which means I'm going through cash faster.
I have a certain core set of groceries that I always keep my kitchen stocked with, and a few other core items that I keep in stock under specific conditions. I'm still doing this the same. I have a system to determine what my "main" meal will be most days, to be purchased either in the form of groceries or take-out, and I still follow the same system. I'm actually impulse purchasing less now that I'm working at home, because I'm never hungry or cranky when I do my grocery shopping.
When I worked in the office, I had a standard breakfast at home before I left for work, bought whatever I wanted for lunch, had my main meal when I got home from work, and grazed from the other food I had on hand if I was still hungry.
Now I start my day with the standard breakfast (which I end up eating later in the morning), don't eat a lunch per se, eat my main meal in the early evening (earlier than when I worked in the office), and grace from the other food I have on hand if I'm still hungry. As far as I can tell, I'm eating either less food or the same amount of food depending. And yet I'm spending a bit more on food.
Apart from the fact that I like eating exactly what I'm craving that particular day, I also theorized that I wouldn't save any significant amount of money
by packing my lunch, because I spent so little on lunches. It was very rare for my lunch bill to exceed $5 and often it was under $3, and I figured that even if I packed my lunch at home, I'd still have to pay for that food. (Not to mention that it's not worth it under a time=money calculation.) I guess that turned out to be right.