Rice can be part of a healthy diet. Globally, the three top countries for life expectancy, in order, are Japan, Singapore, and South Korea. Care to guess what the staple of all three diets is? In the US, we eat 12.3 kg of rice per capita per year, compared to 56.7 in Japan and 67.4 in Korea.
It's all a matter of making sure it's in good proportion with other things. The day's meal plan I laid out got 59% of its calories from carbs, 26% from fat, and 15% from protein, which is within the Dietary Guidelines put out by the US government (which say no more than 65% from carbs). And it contained about three times as much fiber as what is recommended, so it wouldn't be spiking your insulin, since all that rice would take a looooong time to digest when paired with so much fiber (e.g., in a Cuban-style beans-and-rice mix).
What are you eating the rest of the week, or is this an every day, every meal thing?
I talked about this above, but there are comparable options for each of the staples I chose -- like pasta instead of rice, chickpeas instead of black beans, sardines instead of tuna, yogurt instead of milk, canola oil instead of olive oil, etc. The next day, bread, black eyed peas, eggs, cheese, flaxseed oil. The next, barley, pinto beans, chicken thighs, cabbage, and lard. That's four days without a repeated ingredient.
Flour is even cheaper than rice (like around 4,500 calories per dollar). Oats are comparably cheap (2,100 calories per dollar). Peanut butter is also economical (around 1,500 calories per dollar). Barley's another good one, at around 1,400 calories per dollar. Protein tends to be the expensive bit, but you can get eggs at Costco for around 802 calories per dollar. And since beans have a bunch of protein, you don't need to add much if you're including some kind of bean as one of your staples already.
And it's worth remembering the "blue zones" where people live long are almost all places with diets heavy in beans (Okinawa, Loma Linda, Sardinia, etc.)
Sometimes these substitutions will be a little more expensive than my original menu (canned sardines cost a bit more than canned tuna). Sometimes they'll be a bit cheaper (flour's cheaper per calorie than rice). But there are infinite combinations that'll get you $5/day or less, with decent nutrition.
And my calculations were based on buying fairly small amounts from Walmart, without coupons, and without waiting for specials, etc. If you are willing to buy in bulk, things get even cheaper. Like a small bag of black beans at Walmart is 8 cents per ounce. Buy a few 20 pound bags (which will keep forever) from a bulk retailer, and it's 7 cents per ounce. Rice can be 6 cents per ounce in bulk.
Fresh vegetables and fruit are more expensive than the box of Mac and cheese. Go organic and the prices increase.
Yes. To be affordable, you've got to mostly stick to in-season fresh veggies and fruit, and even then treat it more as a garnish than a staple. Like a big bowl of bean chili, with a single cayenne pepper chopped up for flavor. And organic is basically out of the question.