Remember the old cliche, "Unhealthy is cheaper?" To prove this, I recently played the computer game "Spent." (Look up "spent poverty game" on your search engine and you'll see what I mean.) It made me play the role of somebody who has lost her job and has to work minimum wage while keeping a $1000 budget in a month.
One challenge in the game was buying something when I forgot my lunch. I have to either buy a $6 dollar salad or that burger from the "dollar menu," I obviously chose the latter, remembering my role as somebody who is one of the working poor. The results say that low-income workers are likely to become overweight or obese. I knew that even before playing that game.
So, there's one of the reasons why we eat unhealthy. It's often cheaper. I'd rather start a home-based business and grow my own food than get a low-paying job with fast food meals!