A number of studies conclude that depression and fibromyalgia are closely connected.

A person with fibromyalgia is more likely to have depression than a person who does not have fibromyalgia. And some of the most effective drugs to treat fibromyalgia are anti-depressants.

Studies linking obesity and fibromyalgia are more limited:

• A study published in December 2008 found that 45% of people with fibromyalgia were obese. Another 28% were overweight. A smaller study from April of 2009 had similar results.
• Both of these studies found that obesity was associated with more severe symptoms of fibromyalgia.
• A 2005 study found that overweight and obese people with fibromyalgia improved when they lost weight.

These studies shed little light on the cause of fibromyalgia or why obesity and depression are associated with it. Many of the symptoms of these disorders overlap. For example, a person may have fatigue due to depression or fibromyalgia or from both.

It's possible that fibromyalgia actually leads to depression. Having a long lasting, painful condition with no known cause and no ideal treatment, such as fibromyalgia, could trigger depression.

But it's also possible that depression comes first. Having fibromyalgia and depression could make a person less likely to exercise, which increases the risk of becoming obese.

There is reasonably good evidence suggesting a link between obesity, depression and fibromyalgia. The challenge is figuring out what these links mean and what to do about them. Clearly, we have much to learn about fibromyalgia and the conditions that often accompany it.