Why is Resting Energy High? The Science Behind Elevated Metabolism

December 6, 2025 •

5 min read

Resting energy expenditure (REE) accounts for approximately 60–70% of your total daily energy expenditure, fueling your body’s most basic functions at rest. A high resting energy can be caused by various factors, from genetics and high muscle mass to specific medical conditions and environmental influences. Understanding the reasons behind an elevated resting metabolism is key to managing your health and energy levels effectively.

Quick Summary

An elevated resting metabolic rate, also known as high resting energy, is influenced by several factors. Learn about how body composition, genetics, hormones, and certain health conditions can increase the body's energy needs while at rest. This article explains the science behind high resting energy and its implications for your overall well-being.

Key Points

Body Composition is Key: The most significant factor is lean body mass, as muscle tissue burns more calories at rest than fat tissue.
Hormones Control Speed: Hormonal imbalances, particularly hyperthyroidism, can accelerate your metabolism significantly.
Genetics Play a Role: Your resting metabolic rate is partly determined by genetic factors, inherited from your parents.
Illness and Recovery Increase Demands: Acute illness, fever, or recovering from trauma like surgery requires extra energy for the body to heal itself.
Stimulants and Environment Have an Effect: Consumption of stimulants like caffeine or exposure to extreme temperatures can temporarily increase metabolic rate.
High REE Isn't Always Positive: Unexplained high resting energy could indicate hypermetabolism, which can cause symptoms like fatigue, unexplained weight loss, and increased heart rate.
Lifestyle Factors Matter: Regular exercise, a balanced diet, and sufficient sleep are critical for managing your metabolic health.

Understanding Resting Energy Expenditure (REE)

Resting energy expenditure (REE), also known as resting metabolic rate (RMR), is the amount of energy your body burns to maintain basic physiological functions while at complete rest, including respiration, circulation, and temperature regulation. A high REE means your body requires more calories to perform these functions than an average person of the same size, age, and sex. This can be influenced by a complex interplay of physiological and lifestyle factors. While a high metabolism might sound like an advantage for weight management, it can also indicate underlying health issues that need attention.

The Impact of Body Composition and Genetics

One of the most significant determinants of a high resting energy is body composition.

High Muscle Mass: Muscle tissue is far more metabolically active than fat tissue. This means that individuals with a higher percentage of lean muscle mass naturally have a higher REE. Athletes and those who regularly engage in strength training will burn more calories at rest due to their greater muscle density.
Body Size: Simply put, larger bodies require more energy to operate. A person with a greater body weight and surface area will have a higher REE because there is more tissue to maintain.
Genetic Predisposition: Genetics can play a significant role in determining your metabolic rate. Some individuals are born with a naturally faster metabolism due to inherited traits that influence their body's cellular functions and energy use. While lifestyle choices have an impact, your genes lay the foundation for your metabolic speed.

Hormonal and Endocrine Factors

Your endocrine system, which includes your thyroid gland, is a major regulator of metabolism. Hormonal imbalances or overactivity can cause a significant spike in resting energy.

Hyperthyroidism: An overactive thyroid gland produces an excess of thyroid hormones, which can dramatically increase metabolic rate. Symptoms often associated with hyperthyroidism include unexplained weight loss, increased appetite, rapid heart rate, and excessive sweating.
Stress Hormones: The body's stress response can also influence REE. The release of hormones like epinephrine (adrenaline) can increase cellular activity and energy expenditure, even at rest. Chronic stress and emotional excitement can lead to a sustained, elevated metabolic rate.

Acute Illness, Recovery, and Environmental Influences

Certain temporary conditions and environmental factors can also drive up your resting energy.

Fever or Infection: When your body is fighting off an infection, your metabolic rate increases to fuel the immune response. For every degree Fahrenheit of fever, REE can increase by 7% as the body works harder to repair tissues and combat the illness.
Post-Trauma and Surgery: The body's healing process after an injury, burn, or surgery requires a substantial amount of energy. The increased demand for tissue repair and recovery results in a temporarily elevated REE.
Environmental Temperature: Extreme temperatures, both hot and cold, force the body to expend more energy to maintain a stable internal temperature. In very cold conditions, the body increases metabolism to generate heat through shivering. In very hot conditions, it works harder to cool itself down through sweating.

The Role of Stimulants and Diet

Some dietary choices and substances can temporarily increase your metabolic rate.

Caffeine and Nicotine: These stimulants can cause a short-term increase in REE. However, the effect is often minimal and not a sustainable way to influence your metabolism in the long run.
Thermic Effect of Food (TEF): This is the energy expended during the digestion, absorption, and storage of nutrients. Protein has a higher thermic effect than carbohydrates and fats, meaning you burn more calories digesting it.

Comparison of Causes for High vs. Low Resting Energy


Factor	Impact on Resting Energy	Explanation
Muscle Mass	High: More muscle mass	Muscle tissue is more metabolically active, burning more calories at rest.	Low: Less muscle mass	Less muscle means fewer calories burned for maintenance.
Age	High: Younger people	Metabolism naturally slows with age due to decreased muscle mass.	Low: Older people	The natural decline in lean body mass over time leads to a lower REE.
Thyroid Function	High: Hyperthyroidism	An overactive thyroid produces excess hormones that boost metabolism.	Low: Hypothyroidism	An underactive thyroid gland leads to a slower metabolic rate.
Illness / Stress	High: Acute illness, fever, or trauma	The body expends more energy for healing and immune response.	Low: Prolonged malnutrition or restrictive dieting	The body enters a "conservation mode" to save energy during calorie deprivation.
Genetics	High: Inherited traits	Some individuals are naturally predisposed to a faster metabolism.	Low: Inherited traits	Other individuals inherit a slower metabolic rate.
Gender	High: Men generally	Men typically have more muscle mass than women, leading to a higher REE.	Low: Women generally	Women tend to have less muscle and more fat, resulting in a lower REE.

Can a High Resting Energy be a Problem?

While a high metabolism may seem like a desirable trait, especially for weight management, it can be an indicator of other issues if it's abnormally high and unexplained. Hypermetabolism, where the metabolism is excessively fast, can have several negative health consequences, including:

Fatigue and Exhaustion: Burning calories too quickly can deplete energy stores, leading to chronic tiredness.
Unintentional Weight Loss: Significant, unexplained weight loss can be a symptom of hypermetabolism caused by a medical condition.
Nutritional Deficiencies: A high metabolic rate requires a greater intake of nutrients. Without adequate fuel, the body can develop deficiencies.

Conclusion

High resting energy is a complex physiological state influenced by a variety of factors, including genetics, body composition, hormones, and environmental stimuli. For most people, a high REE is a natural result of higher lean muscle mass or other non-pathological factors. However, an abrupt or unexplained increase could signal an underlying medical issue, such as hyperthyroidism or an acute illness. Understanding the factors contributing to your metabolic rate can provide valuable insight into your overall health and energy balance. For any significant changes in resting energy or associated symptoms, it is always recommended to consult with a healthcare professional.

What to do if you suspect a high REE

Assess lifestyle factors: Consider recent changes in diet, exercise, or stress levels. Have you increased your strength training? Are you experiencing more stress than usual?
Monitor symptoms: Take note of accompanying symptoms like unusual fatigue, heart rate changes, or unexplained weight loss, as these can point toward potential medical causes.
Talk to a doctor: A healthcare professional can evaluate your overall health, and run tests if necessary to rule out underlying conditions.
Use tracking tools: Modern fitness trackers provide an estimate of resting calorie burn. While not as precise as clinical tests, they can help identify a trend if your resting energy seems to be changing.

For those who have a naturally high REE, maintaining a sufficient caloric intake is important to avoid unintentional weight loss or fatigue. Conversely, if high REE is due to an underlying condition, treating that condition will typically normalize metabolic function. In all cases, a balanced diet, adequate sleep, and managing stress are fundamental to supporting metabolic health.

Frequently Asked Questions

Resting energy, or resting metabolic rate (RMR), is the amount of energy your body uses to perform basic, involuntary functions while at rest, such as breathing, circulation, and cell repair.

Yes, muscle tissue is more metabolically active than fat tissue. Therefore, having a higher percentage of lean muscle mass will increase your resting energy expenditure.

Yes, an overactive thyroid gland (hyperthyroidism) produces excess hormones that can significantly speed up your metabolic rate and cause high resting energy.

Yes, genetics can play a role in determining your metabolic rate. Some individuals are naturally predisposed to a faster or slower metabolism due to inherited traits.

When you are sick or have a fever, your body increases its metabolic rate to produce energy for the immune response and tissue repair. This causes a temporary increase in resting energy.

Not necessarily. It can be due to natural factors like high muscle mass. However, if it is sudden, significant, and unexplained, it could be a sign of a medical condition like hyperthyroidism or cancer and should be checked by a doctor.

The most accurate way to measure resting energy is through indirect calorimetry, where a person's oxygen consumption and carbon dioxide production are measured. It can also be estimated using predictive equations, though these are less accurate.

No, weight loss typically leads to a decrease in resting metabolic rate because a smaller body requires less energy to function. Restrictive dieting can also cause the body to conserve energy, further slowing metabolism.

Yes, regular exercise, particularly strength training that builds lean muscle mass, can lead to a sustained increase in your resting metabolic rate over time.

Resting Energy Expenditure (REE) and Basal Metabolic Rate (BMR) are very similar, but BMR is a more restrictive measurement taken under very specific, controlled conditions (e.g., after 12 hours fasting, immediately upon waking). REE is a slightly less restrictive measurement that is more commonly used.