I'm no expert, but from the receiving end i believe that acupuncture breaks up energy blockage at the chi sites in the body (chi means energy). Chi is believed to be a primary element, like fire or water. Once any blockages are removed, the healthy flow of energy can resume in the body, and health in general is restored.

I've used acupuncture for years to stop the swelling of osteoarthritis & most of the pain associated with it, and to control headaches that only Vycodin +prednisone could knock out.

My acupuncture doctor uses needles of widely varying diameters & lengths. He also prescribes various herbs, teas, extractions, & other plant-base concoctions. I have as much fait in him, after 20 yrs, as in my AMA doc & for the same sorts of reasons. They work together now.