Smiling for 10 to 15 minutes in a day burns 10 to 40 calories, according to Calorie Count. Researchers at Vanderbilt University showed that laughing burns 1.3 calories per minute depending on the intensity of the laughter and the weight of a person.
Laughing or smiling causes the heart rate to rise by about 10 to 20 percent, explains WebMD. An increase in heart rate causes an increase in metabolism, which results in a continuous burning of calories even after laughing ceases. Besides burning calories, researchers have verified that laughter also provides a workout for the muscles in the abdomen, shoulders, diaphragm and back.