Isn't it weird how fast food is cheaper than healthy foods

I've been thinking on this a-lot and its strange to me. What if it was the other way around? Would we not have as much obesity? I think that would be the case since families who are struggling financially are most likely to pick the cheaper option. Then again maybe it would stir up an even worse possibility like for instance what if people just started wasting even more money on fast food. Then we would not only have obesity but poverty too. I really don't know much about debt or the amount of obesity in the USA but I just think that would be an interesting topic to discuss.