An interesting thought let's work it out.

Breakfast:
Roughly 1/20 of a $3 cereal bag: $0.15
Piece of fruit: ~$0.5
Total: $0.65

Lunch:
Eating in the cafeteria $5-6
or
Packed Lunch
1/12 $2 bread loaf: $0.17
1/10 of $2 cheese: $0.2
1/8 of $4 deli meat: $0.5
1/8 of $2 chip/pretzel/crackers bag: $0.25
1/10 of $3 carrot bag: $0.3
Piece of fruit: ~$0.5
Total: $1.92

Dinner:
Eating out: $8-9
or
Cooking
...
...
Too many possibilities, but let's assume $3-4

Daily average low: $5.57
Daily average high: $15.65

Hmm...
I don't eat out for dinner very often, but I should definitely pack my lunch on a regular basis.

It varies a lot. Like, today I ate 2 lemons (squezed like juice), a spoon of honey, some slices of panetone (a sweet bread), cooked white rice and chicken. In a day like this, 5 dollars at the most.
I cook most of the times, so, it is very cheap.

I do grocery and I spend like 20 bucks a week lol

Being vegie is cheap lol

In 45 years time that good rural house will be $400,000

I used to spend around $3 a day on food.

But ever since I have been eating healthier I spend around $6-$8 a day on food now.

I go to Costco and buy my food there and make my meals at home then take it to work, so I say $2 to $5 a day.

I spend about 20 a day to feed a family of four. We are frugal with preparing meals. That's an average fromy groceries. We try to eat out only twice a month and thats usually Taco Bell and it's about 12 bucks each trip.

I also eat 200 grams of protein each day. Chicken is cheap.

When I go to uni about $5 - $10 AUD

About 20 € for 3 people.