> 2000 calories in Big Macs: $17.87 at a US McDonalds

How did you get that?

According to McDonald's own nutritional information [1], you'd consume 1,070 calories per medium meal. Via:

Big Mac: 530 calories

Medium Fries: 340 calories

Medium Drink: 200 Calories

In order for your maths to work each meal has to cost $8.94. The most expensive medium big mac meal I can find is $8.03 in DC, or $16 for your 2K calories.

[0] http://www.fastfoodmenuprices.com/mcdonalds-prices/

[1] http://www.mcdonalds.com/us/en/food/full_menu/full_menu_expl...

I divided 2000 calories by the calories in a Big Mac and multiplied by the average price of a Big Mac in the US in July 2015. This calculation does not depend on the cost of foods that aren't Big Macs.

Or – for a more traditional comparison – cooking.

I live in a house of 8 where we order food communally, last month my food bill was £93.35 ($145.50), so $4.85/day for three (subjectively very healthy) meals.

Not your typical setup, but still perhaps of interest.