For anthropology, see sedentism.

Sedentary lifestyle is a type of lifestyle most commonly found in modern (particularly Western) cultures. It is characterized by sitting or remaining inactive for most of the day (for example, in an office), without any (or little) exercise. It is believed to be a factor in obesity, and, in doing so, may contribute to other diseases, such as type II diabetes, heart disease, depression and even hemorrhoids. Lack of exercise causes muscle atrophy, shrinking and weakening of muscles, which in turn increases susceptibility to injury. Physical fitness is correlated with immune system function, and a reduction in physical fitness is generally accompanied by a weakening of the immune system.

The term sedentary in biology applies to organisms and species that are not migratory but rather remain at a single location (permanently fixed or otherwise). Examples in zoology include such sessile organisms as barnacles, corals and mussels.

Examples can include the change in telephones. Previously they were connected to cords forcing individuals to get up, but now with cell phones and cordless phones, inactivity and remaining seated occur more regularly.