How important is it to "eat clean"

We need a new definition of food. Instead of clean or junk or whatever, we need a nice shiny word that means compatible with a particular person's health, calorie goals, and satiety signals. Someone invent a new term!

Individually Optimal?

Nah, sounds silly and too many syllables. Humans don't like too many syllables.

Healthy works for me. I try to eat a healthy diet. I try to eat in a way that meets my health goals. (I'd say "healthy and balanced," but some people can intentionally eat unbalanced (i.e., low carb, 80/10/10) and still be healthy and meet their goals, so I'll leave it out.

What everyone means by that will be individual, but that's fine.

I use the term "healthy and balanced" to mean "nutritionally adequate," not "equal macro ratios."

Yeah, I guess I do too. I can just see someone thinking a diet really low in some macro is being excluded by the term.

As long as you are getting the minimums within your calorie goals...and there is no minimum for carbs. While I would never do Keto, it's nutritionally balanced.

Except it's a known fact that these foods are created to manipulate our body and brain chemistry to find them most pleasurable.

Most food is created in an effort to make it most pleasurable. That's what learning to cook teaches you how to do. That's every bit as true about traditional home-cooked meals as marketed stuff, and most people will agree with me that really good home-cooked or restaurant food, cooked to their taste using fresh, whole ingredients (and, sure, butter) is much tastier and harder to resist than packaged stuff or fast food, I expect, although obviously taste is subjective.

It just sounds scarier if it's some big corporation doing that, vs. mom or Julia Child.

If anything, a lot of the additives in packaged food and fast food is because they are trying to make them tasty on the cheap, and as indicated above they still generally don't taste as good. Compare a frozen pizza to a pizza cooked at a really good local pizza place or home-cooked by someone with the right equipment.

If you are claiming that transfats or HFCS or whatever are as addictive as truly addictive drugs, provide the evidence. It's certainly not my experience.

Ignorance is bliss. I'd go into more details but you obviously don't care so fine. You're absolutely right in every way.

Ignorance definitely is bliss. Having survived an actual drug addiction, I can say, hand on heart, that anyone claiming food is as addictive as drugs is ignorant. Yes, they may be contrived to tick all the right pleasure boxes, but they are not addictive like drugs are. Ever seen anyone try and peel the skin off their own face because they can't get their hands on mars bar? No, me neither.

Nicotine is a drug, too, though, and I've never heard anyone claim it isn't addicting, yet some foods are definitely harder for some people to avoid than cigarettes.