system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can people live on an all or almost all junk food diet without getting really sick?

Some people don't even gain weight while living this way. Mostly or even all nutritionless and high sugar/fat/sodium etc. diet, and usually not much exercise. How come you don't see a whole bunch of college students keeling over from heart attacks after living a year on ramen noodles and cheetos?
gpt
You say "nutritionless", but modern processed foods are *extremely* nutritious when compared to anything but a modern balanced diet. They have vitamins and minerals and stuff dumped into them; not perfectly, but enough so that it's hard to get any nutrient deficiency.