The etymology of the low or no carb diet stems from the paleo diet - the diet of humans during the palaeolithic period. It's premise is that the human diet evolved from a foraging lifestyle, and that our dietary switch with the advent of agriculture is ill-suited to our evolutionary biology.
Is this true? Perhaps. There seems to be some evidence for it. And certainly the food pyramids we all remember as children may well have been influenced by industry/market factors as opposed to health science.
However, I think it's dangerous to swallow any supposed diet whole. Unsurprisingly, given how controversial it is, the science is conflicting. To avoid risky health affects from major diet changes, for me, you're better simply having a balanced diet. Of course it can be beneficial to include or remove certain things from your diet to see how it affects you. This is infact a common practice for identifying food allergies.
On top of this, even if you believe the words behind a given diet, how easy it is to apply in practice can be a major issue. Unless you're living rurally where you can possibly source/grow/hunt your own food, it's likely you'll be spending a bit of money for this diet. The fact is, something like bread is cheap. Personally, I'd like to reduce the amount of carbs in my diet, but honestly, it ain't happening to quickly.
[formerly Cthenthar]
Revolutionaries don't spend all day on a messageboard. Action is realisation of the polemic.
"When the lie returns to the mouth of the powerful, our voice of fire will speak again." - quote EZLN
“Development develops inequality.” ― Eduardo Galeano, Open Veins of Latin America: Five Centuries of the Pillage of a Continent