Reddit mentions of Hostess Twinkies 20 individually wrapped twinkies.

Ah, see, you didn't specify that processed foods were banned -- just that you wanted a healthy diet. Pasta is certainly a processed food, but it's not unhealthy.

Twinkies are processed and quite high in sugar and fat, granted, but I'm not advocating eating Twinkies.

I can get a 770 calorie bag of lima beans for $1.89 at Safeway. That's 4cal/cent

A small Big Mac meal at McDonalds: Big Mac, 540 calories, small French fries, 230 calories, small coke 150 calories. I just called my local McDonalds' -- that's $5.78. That's 1.59cal/cent. That Big Mac meal isn't cost/calorie cheaper than those lima beans. Admittedly, that's prepared and served food.

Let's look up a Twinkie, for an example of non-healthy, non-served food. A Twinkie has 150 calories. I can get a 20 Twinkie pack on Amazon for $14 (without free shipping, but I'll be generous and pretend that it has zero shipping). That's 2.14cal/cents.

Let's grab some other stuff I have lying around -- spaghetti. I can get 20 boxes of spaghetti with zero shipping for $27.65. First hit on Amazon, no searching around. That's 1680 calories/box, and 12.15 cal/cent.

I'm eating, right now, a tin of Crown Prince sardines in Lousiana hot sauce. I got a box of 24 of these from Amazon for $25.95, free shipping. Each has 230 calories, so 2.127cal/cent. It's probably not the cheapest form of fish I could get, but I happen to like spicy sardines. It is true that the sardines are slightly more expensive than the Twinkies (I get 6% more calories per penny with the Twinkies).

I'm just not seeing this "prohibitively expensive" bit.

Amazon is a good website for purchasing anything, here's a link for some twinkies: http://www.amazon.com/Hostess-Twinkies-individually-wrapped-twinkies/dp/B0027AR7RU/ref=sr_1_1?ie=UTF8&qid=1331015276&sr=8-1