A word about “healthy” food. I have no idea what that means. To be honest, I’d love for that term to disappear altogether. The World Health Organization describes health as “a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.” If “being healthy” is the equivalent of “being well,” then it is easy to see that the phrase “healthy food” makes little sense. It’s hard to be “well” and be “food” at the same time!
Think about it for a minute from your own perspective in the food chain. Becoming food is not a healthy thing to have happen to you. This is why the antelope runs away from the lion and why many plants, which can’t run away, have developed a number of biochemical toxins to defend themselves.
This looks like healthy kale:
This looks like yummy kale:
But this is not “healthy” kale; it’s dead kale. It might be delicious, and it might help make you a healthy person, but it definitely not “healthy” kale. It isn’t going to grow or propagate. It is—I hope–going to get eaten.
The term “healthy” is appropriately applied to things that live and grow: people, plants, animals, environments, communities, economies. Food—i.e. something about to be eaten—isn’t living and growing. The things we consume as food may or may not allow us to become healthy (well) people in a healthy community with a healthy economy and environment.
Why am I splitting hairs over an over-used term like “healthy food”? Why does it even matter whether or not we refer to food as “healthy” or not? And aren’t some foods always “healthy”—for everyone? Y’know, like spinach, and chocolate?
To answer the first two questions: How we speak reflects how we think. When we use the phrase “healthy foods” there is an underlying assumption that
1) we know and are in agreement about how to define “healthy” foods
2) there exists a specific set of foods that fit this definition, while the rest do not.
Which brings me to the last question, aren’t some foods always “healthy/unhealthy”? Hmm. For someone whose current health status requires a low-fiber diet, kale is not “healthy.” For a kid surviving on a subsistence diet who needs the calories and the 8 essential vitamins and minerals in a bowl of Lucky Charms (not to mention the marshmallow surprises!) cereal is “healthy” (not optimal, not perfect—but better than nothing).
Note that I am not saying “Everything in moderation.” I am saying “Everything in context.”
I can tell you what foods contain the nourishment that humans require; I can tell you what foods frequently create health problems for many people. I can look back on our recent history and tell you what has happened in our food system that has not worked to create a healthy environment, economy, or society. But I cannot determine what foods or what lifestyle will create a state of health or wellness for you right now and certainly not 30 years down the road—no one can but you, and you can really only do that through educated guesswork and listening to the expert within. Nutrition experts can (if properly trained) help you with both of those things, but they can’t if they’ve already determined that they “know” what “healthy” food—for you and everyone else—is.
Eathropology 
Ok, my pet peeve is the word “balanced”. As in, you should eat a balanced diet. Does that mean that the food on my plate should be such that I can balance my plate on my finger or maybe my nose? Or is it taking one food from each aisle of my local convenience store? Or as a diabetic am I forced to eat sugar and candy to balance all of the non-sugary foods?
“Balanced” is a word that lacks any scientific underpinnings whatsoever, although I really like the idea of the trained seal approach to “balancing” your diet. In reality, “healthy food” has no scientific basis either, to the extent that the DGAC 2015 report has to footnote the word “healthy” as soon as they use it (see Chapter 1). Their supplied definition is delightfully Orwellian: “… the term “healthy” is used to represent the concept of “health-promoting” as well as to refer to foods or dietary patterns that are consistent with the Dietary Guidelines.”
So first of all, “healthy” does not actually mean “health-promoting,” but “represents the concept of health-promoting” (whatever that actually does mean).
Even better, “healthy” and “consistent with the Dietary Guidelines” are apparently synonymous and self-defining. 🙂
And if I am eating a low carbohydrate diet and there is sugar in the relish I use, that sugar is “healthy”, if only because the amount of fructose and the total carbohydrate after its addition is too low to ever register in any experimental study as harmful.
But if that same intake of sugar then caused me to crave sugar and eat a sweet desert I hadn’t planned to, and didn’t really want, then it might well be “unhealthy”.
Even though it would be exactly the same thing.
I suppose I’d rather eat healthy food than food that died of disease before it was slaughtered or harvested.
“I suppose I’d rather eat healthy food than food that died of disease before it was slaughtered or harvested.” Perfect! That’s the only definition of “healthy food” we should care about.