"I used to have it at dinner but with all you can eat places springing
up like Starbucks, I now have lunch as the big meal".

I dont bother with lunch at all.
It's cheaper since I cannot eat any more at dinner time than at lunch
time.

Cheaper to not eat out.

Lunch is usually 40% cheaper than dinner. True, dinner might have some
premium choices such as crab legs or shrimps, I think lunch is the
better deal.
Also I wonder if eating a big dinner makes weight gain easier.
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I presume you are relating this to being "frugal".  I do not know if
you're retired or not either.    Lots of us are on a fixed income and it
is a hellof alot cheaper to fix a meal at home.  I eat my big meal
around 1PM...and snack in the late evening.

  Those of us who take cholesterol-lowering meds are usually asked to
take a little something on your tummy with that kind of med.

I only eat out if I have a friend who wants to go out.  If I have a
choice on time of day, I prefer breakfast.  Lots of places have a senior
breakfast.

     I find lots of places, where you sit down and are served, are
cheaper than fast food.  Use to be you went where the truckers eat..now
it's eat where the seniors eat.  If you live near a hospital, their
cafeterias are usually the cheapest any where.

       But being retired we have all the time in the world to prepare a
meal.  Another reason I like a noon meal is because I clean the mess up
then and do not have dirty dishes sitting around in the
afternoon/evening hours.  

      I also prefer eating at home because I have low tolerance for
'waiting' in lines, waiters/waitresses who act like you're interrupting
their social life, and at home, you can eat in your boxer shorts and
post in groups and check your email, while you're eating and you don't
have to figure out what the tip should be.