On average, a 155-pound person burns 42 calories while sitting for 30 minutes, according to Harvard Medical School. The number of calories burned varies based on weight and activities conducted while sitting.
Depending on what types of activities are performed while sitting, calorie burn will differ. Sitting in a meeting at work is estimated to burn 60 calories in 30 minutes for a person who weighs 155 pounds. On the other hand, sitting in class is estimated to burn 65 calories in 30 minutes for a person who weighs the same amount.
Weight as well as muscle mass will determine how rapidly an individual burns calories. People who have more muscle compared to others of the same weight with more fat will burn more calories because it takes a greater amount of energy to fuel muscles.