The modern world encourages a lifestyle defined by sitting, from desk jobs and long commutes to evenings spent on the couch. This sedentary pattern often leads people to question how much energy their body uses when they are not actively moving. The body burns energy constantly, even when motionless. Understanding this baseline expenditure requires looking beyond physical activity to the fundamental processes that keep the body functioning. This breakdown provides a clearer picture of the body’s continuous calorie consumption during a seated day.
Calculating Calories Burned While Still
The primary source of energy expenditure when sitting still is the Basal Metabolic Rate (BMR), which represents the minimum number of calories the body requires for life-sustaining functions. This energy powers unconscious processes such as breathing, blood circulation, and the maintenance of body temperature and organ function. BMR accounts for the majority of a person’s total daily calorie burn, typically making up 60% to 70% of the energy used in a day.
A closely related measure is the Resting Metabolic Rate (RMR), which is often used interchangeably with BMR but is slightly higher because it includes the minimal energy needed for minor, low-effort activities. Predictive equations, such as the Mifflin-St Jeor equation, estimate RMR based on sex, weight, height, and age. A person who is entirely sedentary will burn calories at a rate roughly 1.2 times their BMR or RMR. This base rate translates to a seated energy burn of 60 to 80 calories per hour for an average person.
How Personal Metrics Influence Energy Use
The exact calorie expenditure calculated from BMR or RMR is highly individualized, changing based on specific biological and physical characteristics. Body weight is a significant factor, as a larger body mass requires more energy to maintain the volume of tissue and fluids. Individuals with greater overall body size have a higher BMR simply because there is more tissue to maintain.
Body composition is another determinant, with lean muscle tissue being far more metabolically active than fat tissue. Muscle requires more energy to maintain itself, even at rest, compared to fat cells. Consequently, two people of the same weight may have different metabolic rates if one has a higher percentage of muscle mass.
Age also plays a role in decreasing the RMR over time, primarily because the body tends to experience a loss of muscle mass starting around the age of 30. This reduction in metabolically active muscle tissue slows the overall rate at which the body burns calories. Gender contributes to metabolic differences as well, since men generally have a faster metabolism and higher BMR due to typically having a greater amount of muscle mass.
Adding Movement Through Low-Level Activity
While RMR provides the baseline for sitting, the total calories burned is increased by Non-Exercise Activity Thermogenesis, known as NEAT. NEAT is the energy expended for all physical activities that are not sleeping, eating, or structured exercise. This category includes unconscious movements, such as fidgeting, shifting posture, standing briefly, and walking short distances.
Even subtle movements have a measurable impact on the total energy equation during a sedentary day. For example, a person who fidgets their hands while sitting can burn more calories per hour than a person sitting completely still. These small, non-intentional actions can add a substantial amount to the daily calorie total. The NEAT component can vary by as much as 2,000 calories per day between individuals of similar size based on their job and lifestyle. Incorporating small changes like standing instead of sitting for a portion of the workday can increase the daily calorie burn significantly over a year.