What is Meant by a "Balanced Diet"?

CharlieLopez2005

"Balance" is usually thought of as a positive adjective, but I've never been clear what it means specifically in the context of food choices. Whenever I ask this question of those who recommend a "balanced diet," I receive some of the following responses:

1. Literally, 33% each of the macronutrients--carbs, fat, and protein--or some similar ratio.

2. Following the USDA/Gov't-approved Food Pyramid (i.e. high-carbs, low-fat)--though based on response #1, this is not anywhere close to "balanced" in terms of macronutrient ratio.

3. Portion-controlled cafeteria diet--i.e. there are no "bad" foods per se, only bad portions.

There are probably many more interpretations of "balanced diet," but it just seems to be one of those buzz phrases that a lot of people will think of as solid advice at first blush, but upon closer examination, I get fuzzy as to what it could possibly mean. Thoughts on what "balanced diet" means, or should mean?

Rilke

Eat food. Not too much. Mostly plants.
-Michael Pollan