Let's say that you retire at age 65 and live until 85.
That's 20 years in retirement

20 years times 365 days/year = 7300 days in retirement

I'm going to assume that you like to eat three times a day
I tend to eat more but that's a personal problem that I'm working on

7300 days times 3 meals a day = 21900 meals during retirement

If the average meal cost $5.00 today and include inflation,
in 20 years an average meal could run about $10.00

21900 meals time $10 per meal = $219,000.

Another assumption - if you are married
I would have to assume your spouse would like to eat as well

$219,000 each time 2 people = $438000

$438,000 - and ALL you done is eat

This does not include gifts for the grand kids, traveling, medicine, clothes, etc

If you had $1,000,000 for retirement

$1,000,000 - $438,000 = $562,000

$562,000/20 years = $28,100 per year

$28,100/12 months = $2,341 per month