The condition is called fibromyalgia. It consists of a complex array of symptoms that include widespread muscle and joint pain along with overwhelming fatigue. And none of it goes away, no matter how much rest you get.

Fibromyalgia affects up to 4% of the population -- mostly women. And there is still no known cause or recognized treatment that works for everyone. That's one reason, say experts, that so many people have turned to diet as a way to relieve some of the symptoms.

The fact is there's little scientific evidence to support any single eating plan as a way to deal with fibromyalgia. Nevertheless, a trip around the Internet will show that dietary approaches to fibromyalgia abound. The variety is so diverse it's hard to imagine they are all aimed at treating the same disease.

Eat more whole grains. Don't eat any whole grains. All fruit is good. Some fruit is bad. Tomatoes are healthy. Tomatoes are harmful. Sugar is bad. Sugar has no impact. Avoid meat. Eat. . . .

Confused? Don't be. Experts say diversity is another hallmark of fibromyalgia.

"This is because fibromyalgia is not a specific illness," says Michael McNett, MD. McNett directs the Fibromyalgia Treatment Centers of America, headquartered in Chicago. "Fibromyalgia is more like a symptom complex, and different people appear to have different reasons why they get this symptom complex," he says. "So what works for one person very frequently does not work for another."

And this, say experts, includes dietary measures.

Kent Holtorf, MD, is the medical director of the Holtorf Medical Group Center for Endocrine, Neurological and Infection Related Illness in Torrance, California. He says, "We're at the point now where we know diet plays a role in this disease -- it's just not the same diet for everybody. And not everybody is helped in the same way."

Assess Your Symptoms: Take the WebMD Fibromyalgia Health Check