At a glance
Metabolic rate is the total number of calories burned each day. It includes calories burned by your resting metabolism, the energy required for digestion, and the energy used in physical activity. Each person has a unique metabolic rate influenced by lifestyle, genetics, and body composition. Increasing daily movement, building muscle mass, practicing intermittent fasting, and adopting a supportive diet are effective ways to burn more calories and support weight loss.
Total metabolic rate is how much energy your body uses each day to function. It influences how your body burns fat, maintains muscle, and how it responds to changes in diet and activity.
Discover what determines your metabolic rate and learn how lifestyle changes can affect how many calories your body burns each day, even at rest.
What is total metabolic rate?
Total metabolic rate is the number of calories your body uses in a day to sustain all its functions and activities. In clinical nutrition and exercise science, total metabolic rate is often referred to as total daily energy expenditure (TDEE).
TDEE is the sum of three distinct components: basal metabolic rate (BMR), the thermic effect of food (TEF), and the thermic effect of physical activity (TEPA).
Basal metabolic rate (BMR)
BMR represents the body’s rate of energy consumption at complete rest. Basal metabolism powers everything from breathing and repairing cells to pumping blood, synthesizing proteins from amino acids, and regulating body temperature.
BMR is often used interchangeably with resting metabolic rate (RMR), which is acceptable in most cases, though technically they’re slightly different.
BMR is measured under specific conditions in which the body has been fasted and rested for a set period. RMR, or resting energy expenditure, is more of an approximation of BMR measured under less strict conditions, but it can serve as a reasonable estimate.
Both account for the largest portion of TDEE, often 60 to 70 percent, making them the primary drivers of how many calories the body burns each day.
Thermic effect of food (TEF)
Breaking down food and forming new molecules requires energy. TEF refers to the energy the body expends digesting, absorbing, and processing nutrients.
TEF accounts for around 5 to 15 percent of TDEE, though this varies by macronutrient. For example, protein requires the most energy, with up to 30 percent of its caloric value expended during digestion, whereas carbohydrates require 5 to 10 percent, and fat requires 0 to 3 percent.
Thermic effect of physical activity (TEPA)
TEPA measures all the energy spent through physical movement. This includes structured workouts, such as aerobic exercise or resistance training, which are classified as exercise activity thermogenesis (EAT).
TEPA also accounts for everyday movements, such as walking, working a physical job, or even fidgeting in your chair. This type of movement is called non-exercise activity thermogenesis (NEAT).
EAT and NEAT combined are estimated to account for roughly 15 to 30 percent of TDEE, depending on personal factors.
Watch the video below to learn about natural ways to encourage fat burning.
What determines your metabolic rate?
An individual’s energy needs are highly variable and influenced by several personal factors, including body type, environment, diet, and lifestyle.
Here are six primary determinants that shape your body’s metabolic rate.
1. Body size and body weight
Larger bodies contain more cells and tissue to maintain and therefore have higher energy requirements at rest.
Total body weight is a primary input in most predictive equations for calculating metabolic rate, though the ratio of lean body mass to fat mass is more informative than weight alone.
2. Muscle mass
Having more lean muscle can increase the amount of calories you burn per day. Muscle is three times more metabolically active than fat even at rest, and burns roughly 6 to 10 calories per pound daily, whereas fat consumes only about 2 to 3 calories per pound.
3. Hormone levels
Hormones act as the body’s chemical messengers, and several, such as thyroid hormones, cortisol, insulin, leptin, and growth hormone, directly regulate metabolic functions.
Changes in hormone levels due to age, pregnancy, medications, lifestyle, or environmental factors can therefore directly affect metabolic rate and body weight.
4. Physical activity and movement
Higher rates of movement lead to a greater demand for energy in the body. Physical activity can account for a difference of up to 2000 calories in daily energy expenditure between individuals of similar body size and living conditions.
5. Age and metabolic adaptation
With age, metabolism naturally slows down due to declining hormone levels, loss of muscle mass, and less daily activity. This shift explains why older adults generally require fewer calories to maintain their weight.
Interestingly, research published in Science shows that while metabolism remains fairly stable from age 20 to 60, it gradually declines after age 60, even after accounting for body size and composition.
6. Environmental and lifestyle factors
Environmental temperature, sleep quality, and chronic stress all modulate metabolic rate. Exposure to extreme temperatures increases the energy expended to maintain body temperature, while poor sleep and high stress can elevate cortisol, which suppresses fat-burning hormones and promotes fat accumulation.
Strategies to increase metabolic rate
Many people want to know how to improve their metabolic rate to help them burn fat and lose weight. Fortunately, while some factors like age and genetics are fixed, your metabolic rate is largely influenced by daily choices.
Here are four strategies to help maintain and support a healthy metabolism.
1. Strength building
Resistance training is one of the most reliable ways to increase resting metabolic rate in the long term. Strength training exercises build lean muscle mass, which raises the body’s baseline energy requirements at rest—helping it burn calories more effectively.
Research published in the Journal of Applied Physiology found that resistance training increased lean muscle mass and spontaneous physical movement in older adults, resulting in about a seven percent increase in resting energy expenditure and a 12 percent increase in total energy expenditure.
2. Stay physically active throughout the day
Adding short movement breaks throughout the day can be an extremely efficient way to help increase TDEE. It typically requires no recovery time or equipment and is often easier for most individuals to adhere to.
While structured exercise is important for building and maintaining lean muscle mass that supports healthy metabolism, individuals who work out but have low NEAT are still at risk of metabolic imbalances and weight gain.
Research published in Mayo Clinic Proceedings highlights that “Sitting time is independently associated with an increased risk of diabetes and total mortality, regardless of physical activity level.” This underscores the importance of incorporating everyday physical movement alongside planned exercise.
You can increase NEAT in several convenient ways, such as walking and standing more often, doing housework, or even pursuing hobbies like gardening, dancing, or cooking.
3. Dietary support
Diet influences metabolic rate through several interconnected mechanisms, including its effects on TEF, cellular energy production, and hormone levels.
Getting enough protein is essential to maintain and build muscle mass. It also expends the most energy during digestion, supporting enhanced thermogenesis.
In addition, reducing carbohydrate intake, specifically through the adoption of a very low-carbohydrate or Healthy Keto® diet, has been associated with enhanced mitochondrial health and increased fat burning by promoting ketone production and supporting balanced insulin and blood glucose responses.
Mitochondria are the cellular structures responsible for converting fuel into usable energy, and their efficiency and density directly influence how much energy the body can produce and sustain.
Evidence published in the Journal of Health, Population and Nutrition highlights that a ketogenic diet has been associated with reductions in fat mass and increased fat oxidation, with no significant adverse effects on muscle mass or strength.
Watch the video below to learn which foods may contribute to a slower metabolism.
4. Intermittent fasting
Many people turn to calorie restriction to encourage the body to burn fat. While too many calories can cause the body to gain weight, extreme calorie restriction can often backfire. This approach can trigger adaptive thermogenesis—a survival response where the metabolism slows to conserve energy in the face of perceived starvation. This often leads to intense food cravings, muscle loss, and frustrating weight-loss plateaus.
Intermittent fasting (IF), specifically time-restricted eating, offers a different approach. Rather than focusing solely on how much you eat, it prioritizes how often you eat. By maintaining a 16-hour fasting window, you can help give the body a break from the hormone that dictates fat storage: insulin.
Most meals and snacks trigger insulin release. When insulin levels are high, the body is in fat storage mode. When they are low, the body can more easily access and burn stored fat for fuel. This hormonal shift allows you to eat adequate, nutritious calories to support your metabolism while still promoting fat loss—a balance that continuous snacking and extreme restriction often fail to achieve.
“Many people cut calories but end up snacking all day, triggering insulin and thereby encouraging fat storage,” explains Dr. Berg. “Reducing meal frequency helps keep insulin low, and encourages the body to start burning its own fat for fuel.”
Key takeaways
- Metabolic rate is the speed at which your body converts nutrients into energy to power vital functions and physical movement.
- Your total metabolic rate is the sum of your basal metabolic rate, the thermic effect of food, and physical activity.
- While age and genetics play a role in metabolism, other factors, such as body composition, diet, lifestyle, and activity levels, are also major drivers of your metabolic rate.
- You can support a healthy metabolism through resistance training, consistent daily movement, intermittent fasting, adopting a Healthy Keto® diet, and eating enough protein.
FAQ
- 1. What is the difference between basal metabolic rate and resting metabolic rate?
- 2. Can you actually increase your metabolic rate?
- 3. What is the most accurate way to measure metabolic rate?
- 4. How do I calculate my metabolic rate?
