Here is a post from a forum I sometimes haunt. There is a surprising list of health and life improvements that people report.
A big surprise for me was that I stopped snoring within a few weeks of going low carb. PaleoPathologistMate was incredibly delighted with this and when the Mate is happy (and ahem rested,) so am I. My reflux disease stopped being a problem fairly quickly as well. (It returns if I eat too many carbs or have wine with dinner. Kind of a bummer but for me the benefits of no GERD are huge.) I also got my first case of sinusitis in a long time this year after a week in smoke, dust, wind, heat, humidity in Managua, Nicaragua; first real sickness in a good while, seems like my sinuses are a lot healthier. And last spring was supposed to be a heavy pollen load, and my usual hay fever actually seemed better controlled.
I know of people who claim that depression has decreased, digestive problems improved, skin healthier, increased perceived energy level, and many other things. One young woman told me she is completely off antidepressants and no longer has terrible irritable bowel symptoms.
Don't know what to do with all this as yet; as a doc I'm FULLY aware of the power of the placebo effect and suggestion. I also know the word "anecdotal."
On the other hand...if it IS all anecdotal and placebo...and I feel better...who really cares? These are good hypotheses for someone to test (if they can overcome their biases, and the funding organizations' biases--see previous post.)