This TDEE calculator will estimate how many calories you burn daily and your food energy requirements. It uses formulas developed by the Institute of Medicine of the National Academies and covers all age groups, including pregnant and nursing mothers. For children, pregnant and lactating women, it includes the energy needs associated with the deposition of tissues and milk production.
For individuals having average weight (BMI between 18.5 and 25), the calculator calculates EER (Estimated Energy Requirements). EER estimates the average amount of calories you need daily to balance out your body's expenditure of energy to maintain body size and composition at a level of physical activity consistent with long-term good health.
For overweight and obese individuals, the calculator calculates TDEE (Total Daily Energy Expenditure). Consider it as the maintenance energy needed to maintain your current weight. Energy is required to support your body's autonomic systems and to perform physical activities. To lose weight, create an energy deficit by eating fewer calories than your TDEE. In this way, you burn more energy than you take in, resulting in weight loss.
The chemical bonds in the foods you eat get broken down through oxidation. The elements that combine with oxygen produce mainly carbon dioxide, water, and heat to maintain body temperature. Energy gets transferred to an intermediate chemical form - ATP, the primary energy source for most cellular processes and is considered the body's "energy currency."
Your energy balance depends on the amount of food energy you take in and the amount of energy your body expends. Imbalances between these two amounts will result in gains or losses of mostly body fat, muscle, and some other components. They determine changes in your body weight.
Your TDEE Changes with Body Weight
TDEE, your total daily energy expenditure, consists of 3 primary components; RMR, TEF, and TEPA.
Your RMR, Resting Metabolic Rate, is the daily energy required to support your body's autonomic systems such as breathing, the nervous system, circulation, and regulation of body temperature while at rest. Energy is also required to support your muscles and fat tissues even while at rest. When you lose weight, you lose some muscle mass along with body fat. Since it takes a lot more energy to maintain muscle than fat, a decrease in muscle mass is associated with a noticeable reduction in your RMR. RMR contributes around 60 to 75% of your TDEE.
The TEF, Thermic Effect of Feeding, is the energy required to digest, absorb, transport, metabolize, and store consumed food. It accounts for approximately 10% of daily calorie burn. Decreasing your daily calorie intake for weight loss also reduces your TEF because of less food to process.
TEPA, the Thermic Effect of Physical Activity, can account for 15 to 30% of daily calorie burn depending on your physical activity level. TEPA includes structured exercises as well as non-structured activities such as fidgeting and shivering. The lower your body weight, the less energy it takes for your muscles to move your body around.
These three components taken together explain why your TDEE decreases with weight loss. In contrast, your TDEE increase with weight gain.
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