Finding could help the elderly or sick who lose interest in food, researchers say.

Laughing can boost the appetite in the same way that exercise does, a finding that could help people eat more when they're sick or depressed, a researcher says.

"The value of the research is that it may provide those who are health-care providers with new insights and understandings and thus further potential options for patients who cannot use physical activity to normalize or enhance their appetite," Dr. Lee S. Berk, a preventive care specialist and psycho-neuro-immunology researcher at Loma Linda University's Schools of Allied Health and Medicine in California said in a news release from the Federation of American Societies for Experimental Biology.

Berk and a colleague have studied laughter and contend that "Laughercise" -- their term for repetitive "mirthful laughter" -- boosts the immune system.

In the study, Berk and colleagues recruited 14 volunteers to watch different kinds of videos -- funny or distressing -- over a three-week period.

Those who watched funny videos experienced changes in hormone levels that are linked to greater appetite. The changes are similar to those experienced by people when they exercise moderately.

"We are finally starting to realize that our everyday behaviors and emotions are modulating our bodies in many ways," Berk said.

The study was to be presented at the annual Experimental Biology meeting, April 24 to 28, in Anaheim, Calif.