The process of weight management is governed by the balance between energy consumed and energy expended. Achieving weight loss requires the body to burn more calories than it consumes, a state known as an energy deficit. Many people wonder if the calories burned simply by existing contribute to this goal. Understanding how the body expends energy throughout the day provides the answer.
Defining Resting Energy Expenditure
The calories the body burns at rest are formally referred to as Resting Energy Expenditure (REE). This energy represents the minimum number of calories required to power the body’s most basic, life-sustaining functions. These unconscious processes include breathing, circulating blood, regulating body temperature, and maintaining organ function.
For most individuals, this resting burn accounts for the largest fraction of their daily energy output, typically 60% to 75% of total calories burned. REE is often used interchangeably with Basal Metabolic Rate (BMR), though BMR is technically measured under stricter laboratory conditions. The term REE is frequently used to describe the baseline metabolic rate for practical purposes. This energy expenditure continues around the clock, regardless of activity level.
Understanding Total Energy Expenditure
To determine the total number of calories burned in a day, it is necessary to consider the Total Energy Expenditure (TEE), which is the sum of all energy used by the body. REE is one of three main components of this daily total. The second component is the Thermic Effect of Food (TEF), which is the energy required to digest, absorb, transport, and store consumed nutrients. TEF typically accounts for a small portion of daily calorie burn, usually around 10% of the total calories consumed.
The third component is Activity Energy Expenditure (AEE), which is the most variable part of the TEE equation. AEE covers all physical movement, from structured exercise to daily, low-intensity movement. This includes energy burned during deliberate workouts and Non-Exercise Activity Thermogenesis (NEAT). NEAT includes activities like fidgeting, standing, and carrying groceries, and it can vary significantly between individuals.
Calculating the Calorie Deficit
The answer to whether resting calories count toward a deficit is yes, because REE is the largest part of the TEE. A calorie deficit is achieved when the energy consumed (Calories In) is less than the total energy expended (TEE). Since TEE is calculated by adding REE, TEF, and AEE, resting calories are inherently included in the body’s daily energy requirement.
For example, if an individual’s TEE is 2,500 calories per day, achieving a 500-calorie deficit requires consuming 2,000 calories. The deficit is created by consuming fewer calories than the total burned, meaning the body must draw on stored energy, such as body fat, to cover the gap.
The body does not prioritize burning activity calories over resting calories; all components of the TEE represent a single total pool of energy needed. Every calorie burned at rest contributes to the total daily expenditure that must be surpassed by a lower caloric intake to initiate weight loss.
Factors that Influence Resting Calorie Burn
While resting calories are consistently included in the deficit calculation, the actual number varies widely from person to person. Body composition is a primary factor, as muscle tissue is more metabolically active than fat tissue. People with more lean muscle mass burn more calories even at rest, making strength training an effective strategy for increasing daily calorie burn.
Key Influencing Factors
Age also plays a role, as REE tends to decrease due to a natural loss of muscle mass. Biological sex influences the burn rate, with men generally having a higher REE than women of the same age and weight because they typically carry a greater percentage of muscle mass. Additionally, genetics and the function of the thyroid gland can affect an individual’s resting energy needs.