The Most (In)efficient Way to Complete the Taco Bell $20 Challenge

The Taco Bell $20 Challenge is "a game in which a participant or participants must consume twenty US dollars worth of food items from Taco Bell restaurant in one sitting." The goal then should be to get to $20 in the most inefficient way possible: in other words, maximize cost while minimizing the amount of food.

First, a couple of caveats in order to maintain the spirit of the challenge:

1. The $20 has to be food only, no drinks
2. I removed all dessert items. Otherwise it would be pretty easy: order 20 orders of Cinnamon Twists and/or Cinnabon Delights

I used the weight of each item (in grams) as a proxy for its respective size (since we ultimately care about volume), and then aimed to minimize this within the constraint of spending at least $20. I used a Simplex Linear Program to do so, and found the following optimal order:

Data sources: Prices - Fast Food Menu Prices, Weights - Calorie Count

For contrast, choosing 20 Cinnabon Delights and/or Cinnamon Twists (both are the same price and weight) would be a clearly superior strategy:

But this is banned under my caveat. What if we make things a bit more interesting, and don't allow more than 1 of the same item?

This results in a 19% increase in weight, but adds a bit of variety to the order.