This argument has been rehashed several times here on HN. Do a site search (use Google or searchyc) for Gary Taubes, or pretty much any nutrition-related subject, and there will be a thread about why a calorie-balanced diet is only a very small part of the nutritional picture.

> Don't consume carbs? This sounds insane. What about a balanced diet of caloric value inline with one's caloric output?

What about it? It's not necessary. If you look for it, you can find lots of examples of societies that were quite healthy on diets that weren't "balanced". One popular example is the Inuit, who got 75% of their energy intake from fat (largely seal and whale blubber) because that was what was available to them whereas fruits and grains and vegetables were not.

http://en.wikipedia.org/wiki/Inuit#Diet