For the most part, eating out is more expensive. It really depends on where you go and what you cook.
The grocery store is my downfall. I usually can't leave without spending less than $30 for one meal. It turns into a "I need this" adventure
Also, sometimes I need spices that aren't available in the 99 cent bag, so I have to shell out $6 for a container of something like Poppy Seeds. I tend to keep my spice rack stocked, but sometimes it's a new spice I've never used. Luckily when I spend that $6, it lasts a while.
When it comes to fast food, yeah, it can be cheaper. My bf and I went to Bakers Drive Thru yesterday and got a bunch of food for $7.71. I didn't have to get the soda, so it could have been $6. The fries were optional too, so it could have been $5. Since its not a restaurant, we didn't have to tip (which is another problem with eating out... I was a server, I have to tip at least $4).
When my bf and I eat out at restaurants, we usually just get waters and share an entree. We can leave spending $13 after tip. Often we even have leftovers from our 1 meal. Not bad for 2 people.
The other day, I made vegan chili. I used almost everything I already had (which I had to pay for at one time, but it was pretty cheap stuff like onion, canned tomato, spices, canned beans, bottle of beer). Probably cost $2 a serving compared to $6 at a restaurant.Here's a tip
for people who dine out: Ever been to a restaurant that has a survey you can fill out through the internet or on the phone (on the receipt) where they send you a gift certificate or coupon? USE THOSE! I started doing it and ended up with: free $9 guacamole at El Torito, $10 gift card from Cheesecake Factory, a free dessert or appetizer from CPK... and some other stuff.