By Stuart Qualtrough
It's no match for running, cycling or pumping iron but scientists claim laughing out loud for up to 15 minutes a day burns 10 to 40 calories.
It's no match for running, cycling or pumping iron but scientists claim laughing out loud for up to 15 minutes a day burns 10 to 40 calories, the amount in a small piece of chocolate.
"We calculated that this is equal to 2 kilograms a year if you do it every day," Dr Maciej Buchowski, of Vanderbilt University Medical Center in Nashville, Tennessee, told participants at an obesity conference last week.
Laughing makes people feel good and has been described as the best medicine. Buchowski believes he and his colleagues are the first to measure how much energy it takes to laugh.
"We discovered that laughter produces energy," he said.
They recruited 100 students who were friends or couples and measured the energy expenditure of each pair while they watched television comedy clips in a metabolic chamber.
The sealed room enabled scientists to measure how much energy the laughter produced while a heart monitor also tracked their heart rate.
Buchowski and his team did not tell the students, who were advised not to talk or move, the goal of the experiment.
"It's not easy to catch genuine laughter because if you tell people you are going to measure laughter they will force the laugh," said Buchowski.
To measure the students' resting metabolic rate the scientists showed them scenes of the English countryside.
They taped them as they watched 10 minutes of comedy interspersed by 5 minutes of the country scenes for longer than one hour.
After analysing the tapes second by second to look for waves of laughter they found that the male students laughed more than the females.
"We found that when people were laughing the increase was about 20% above the basic metabolism rate," Buchowski explained.