By Pat Anson, Editor

Those of us who made a New Year’s resolution to lose weight have a little more incentive to keep our pledge – thanks to new research showing that even a small weight loss reduces overall body pain, as well as fatigue and depression.

The University of Michigan study, published in The Journal of Pain, involved 123 obese participants who were put on a low-calorie liquid diet for 12 weeks and asked to gradually increase their physical activity. The goal was to lose at least 10 percent of their body weight.

“It’s been known for some time that people who are obese tend to have higher levels of pain, generally speaking,” says Andrew Schrepf, PhD, a research investigator at Michigan Medicine’s Chronic Pain and Fatigue Research Center. “But the assumption has always been the pain is going to be in the knees, hips and lower back — parts of the body that are weight-bearing.”

Schrepf and his colleagues found that losing weight not only lowered pain levels in the knees and hips, but in unexpected areas such as the abdomen, arm, chest and jaw. Study participants who could reach the goal of losing 10% of their weight also reported better mental health, improved cognition and more energy. Men in particular showed improvements in their energy levels.

The results are significant because previous research hasn’t shown how weight loss affects widespread pain throughout the body.

“We know when people lose a lot of weight they tend to feel better,” Schrepf says. “But astonishingly, no one ever looked at where in the body the pain gets better.”

Researchers surveyed participants about their pain and other symptoms before and after the 12 week diet, using fibromyalgia assessment criteria to make their determinations. Participants were also evaluated and counseled by physicians and dietitians who specialize in endocrinology and obesity medicine.

Of the 123 participants, 99 were able to lose 10 percent or more of their body weight.

“The focus in the program is on calorie restriction and long-term weight loss, although all patients are encouraged to get more physically active for the other health benefits that exercise provides,” says Amy Rothberg, MD, an associate professor of endocrinology nutritional sciences at U-M. “The truth is people are, paradoxically, far more energetic on a low-energy diet and find after they begin losing weight that they can do more and are more physically active.”

Participants who met the weight loss goal reported widespread improvement in pain compared to those who did not. Their blood samples also showed a spike in anti-inflammatory molecules — a key weapon in fighting many types of pain. Researchers say the widespread improvement in body pain suggests that joints aren’t the only conduit of chronic pain.

“What we think that means is this process of losing weight may be affecting the central mechanisms of pain control related to the brain and spinal cord,” said Schrepf.

In future research, the team hopes to better understand why losing 10% of body weight was the dividing line for reduced pain.

“Some of your earliest weight loss isn’t all fat; it could be water,” Schrepf says. “Somewhere around 10 percent we’re reaching some kind of critical mass, but it’s hard to know exactly what that means.”