The discovery that laughing may have the same effect on appetite as exercise could lead to ‘laughter treatment’ for patients who have lost their interest in food
A hearty laugh can unleash some of the same changes in the body’s chemistry as a quick bout of physical exercise, scientists claim.
People who watched funny movies or comedy acts experienced the same hormonal changes that follow exercise and that are thought to boost appetite, they say.
The finding could lead to the development of better ways to encourage healthy eating among patients who have gone off their food because of depression or other medical conditions.
The study builds on previous work in which the same scientists claimed prolonged laughter can lower blood pressure and boost immune activity. “It may indeed be true that laughter is a good medicine,” said Lee Berk, a preventative care specialist who led the latest research at Loma Linda University in California.
In the study, 14 volunteers were assigned at random to watch either a stressful or a humorous 20-minute video. The stressful video was the brutal opening sequence of Steven Spielberg’s 1998 movie Saving Private Ryan, which depicts a group of US soldiers landing on Omaha beach during the second world war. Participants assigned to watch a humorous video could choose among a variety of comedy movies and stand-up acts.
A week after watching their first video volunteers were shown the opposite genre video so their reaction to both could be compared.
Berk’s team measured levels of two hormones in the volunteers’ blood called leptin and ghrelin, both of which are linked to appetite. While stressful movies had no clear effect on the hormones, mirthful videos caused leptin levels to fall and concentrations of ghrelin to rise. A similar effect is seen after physical exercise and is believed to stimulate appetite.
The study does not prove that laughing improves appetite or fitness, but Berk said “it may provide … further potential options for patients who cannot use physical activity to normalise or enhance their appetite.” The research was announced at the annual Experimental Biology conference in Anaheim, California, today.
The work could improve treatments for people in chronic pain and elderly patients, who can lose their appetites and develop wasting diseases, the researchers said. “We are finally starting to realise that our everyday behaviours and emotions are modulating our bodies in many ways,” said Berk.
Robert Provine, a psychologist at the University of Maryland and author of Laughter: A Scientific Investigation, said it is difficult to untangle whether the physiological effects are caused by the act of laughing or something else.
“An essential consideration about laughter is that it is a vocalisation that evolved to change the behaviour of other people, like talking. We do not have discussions about the health benefit of talking. Laughter did not evolve to make us healthy, although it may do so in indirect ways,” he told the Guardian.