An unhealthy body can be many shapes. Think of the starving people in Ethiopia. They are very unhealthy but they are not fat. I also know many fat people who are very healthy. So being fat or not fat is separate from being healthy.
It's not just your energy levels that suffer. It's your brain. Your brain needs certain nutrients to work properly. If it doesn't have them, it does all sorts of wild things. You might not even realize how "unhealthy" your brain is behaving, if you don't know how it could be when healthy.
It might be that a key reason you feel sad, pathetic, and lonely - which is a shame!! - is because of the low health levels of your brain. It could be that you'd be happier, content, and more at peace if your brain had the nutrients it needed to run smoothly.
Bad food isn't better tasting. In most cases it's worse tasting. And it doesn't make you feel better. It most cases it makes you feel worse, because it sends you on highs and lows. So there's no "benefit" to eating bad food, and there's many down sides. I.e. if I looked at a boring bowl of spaghetti or a delicious fresh-herb eggplant parm dinner, I would avidly go for the eggplant parm because it is so much tastier.
So maybe we could brainstorm about why the things you currently eat seem to be your only options, when there are so many delicious things in the world to eat.