Nitpick: US per-capita calorie consumption is 3782kcal/person/d (source). Some of that is waste and pet food which can be reduced in a disaster scenario, but most of it isn’t. Use of 2000kcal/d as a placeholder number for typical dietary intake is a pet peeve of mine; for most adults, 2000kcal/d is a mild weight-loss diet. A lot of people get tripped up by this when they first start trying to quantify their intake, and falsely assume that the 2000kcal/d number is typical and normative when in fact none of the careful sources are using it that way. (Actual needs vary based on height, activity level, age, weight, and other factors; the way to get a real estimate for the calorie requirements of a specific adult is to use the Harris-Benedict equation to get a BMR and multiply it by an activity factor.)
Nitpick: US per-capita calorie consumption is 3782kcal/person/d (source). Some of that is waste and pet food which can be reduced in a disaster scenario, but most of it isn’t. Use of 2000kcal/d as a placeholder number for typical dietary intake is a pet peeve of mine; for most adults, 2000kcal/d is a mild weight-loss diet. A lot of people get tripped up by this when they first start trying to quantify their intake, and falsely assume that the 2000kcal/d number is typical and normative when in fact none of the careful sources are using it that way. (Actual needs vary based on height, activity level, age, weight, and other factors; the way to get a real estimate for the calorie requirements of a specific adult is to use the Harris-Benedict equation to get a BMR and multiply it by an activity factor.)
I might think daily expenditure per person could even increase after a large scale nuclear war as more people need to engage in more physical labor.