Shedding weight can knock down levels of inflammatory cells and proteins in the body, a new study shows. Since chronic inflammation is a risk factor for many cancers, the new findings suggest weight loss might reduce cancer risk.
But the inflammation reduction only came with weight loss from dieting. People who embarked on an exercise-only program failed to lower their inflammatory load substantially, despite losing several pounds in many cases. The report appears in the May 1 Cancer Research.
“This is very promising,” says Gloria Ho, a cancer epidemiologist at the Albert Einstein College of Medicine in New York City. “This is a good study showing that if you reduce body weight you can actually lower these inflammatory markers.”
A three-way link between inflammation, obesity and cancer risk has been previously established, says study coauthor Anne McTiernan, an internist and epidemiologist at the Fred Hutchinson Cancer Research Center in Seattle. For instance, obesity has been linked to increased blood levels of a protein called C-reactive protein; those increased levels are also associated with an increased risk of breast, colon and lung cancers.
The new findings indicate that the obesity-inflammation segment is modifiable, McTiernan says, but it doesn’t address the cancer risk.
McTiernan and her colleagues randomly assigned 399 overweight and obese postmenopausal women to one of four groups — dieting plus exercise, dieting only, exercise only or a control group not required to do either.
People assigned to the dieting groups lost 8.5 to 10.8 percent of their body weight on average during the study, while those assigned to an exercise-only plan lost an average of just 2.4 percent.
Blood tests before and after the 12-month trial showed that women assigned to dieting who lost at least 5 percent of their body weight, with or without exercise, had substantially greater decreases in levels of inflammatory proteins and cells than the control group. That group showed no change in the inflammatory markers.
Scientists’ understanding of the role of fatty tissue in the body has grown as the obesity epidemic has spread. “We now know that fat isn’t just passive energy storage,” says Russell Tracy, a biochemist at the University of Vermont in Burlington. “It’s an active endocrine organ” that affects other aspects of the body; for example, fatty tissue contributes to chronic inflammation.
“Anything you can do to decrease your inflammatory status is probably a good thing overall,” he says, because the association between obesity and inflammation plays out in many conditions, including atherosclerosis and type 2 diabetes.
“If you can tone all that down,” Tracy says, “you’re better off. And losing weight is a good way to do it.”