What is the difference between REE and TEE nutrition?

According to the National Institutes of Health, your resting metabolic rate (part of REE) accounts for 60 to 75% of your daily energy expenditure. Understanding the difference between REE and TEE nutrition is crucial for anyone looking to accurately manage their calorie intake, whether for weight loss, maintenance, or gain.

Quick Summary

This article defines and contrasts Resting Energy Expenditure (REE) and Total Energy Expenditure (TEE) by breaking down their components and practical applications in nutrition. It also explains how various factors influence these metrics and how they are used to estimate daily caloric requirements.

Key Points

• REE vs. TEE: REE is your baseline metabolism at rest, while TEE is your total daily calorie burn, including activity and digestion.

• Largest Component: REE typically makes up the largest portion (60-75%) of your total daily energy expenditure.

• Variable Factor: The activity energy expenditure (AEE), a component of TEE, is the most variable part of your daily calorie burn.

• Calculation Method: To find your TEE, you calculate your REE and then multiply it by an activity factor that represents your daily movement.

• Weight Management: For weight loss, your calorie intake should be less than your TEE; for maintenance, it should equal your TEE.

• Influencing Factors: Your REE is affected by age, gender, and body composition, whereas your TEE is primarily affected by your physical activity level.

Understanding the Fundamentals: REE and TEE Explained

In the world of nutrition and weight management, calculating daily calorie needs is a fundamental step. The process, however, can be confusing, largely due to two acronyms: REE and TEE. While often discussed together, they represent two distinct measures of energy expenditure with different roles in determining your nutritional requirements.

What is Resting Energy Expenditure (REE)?

Resting Energy Expenditure (REE) is the amount of energy your body burns to perform basic, involuntary physiological functions to sustain life while at complete rest. This includes essential processes such as breathing, blood circulation, cell production, nutrient processing, and maintaining body temperature. REE is the largest component of your daily calorie burn, typically accounting for 60 to 75% of your total energy expenditure. It is slightly higher than the Basal Metabolic Rate (BMR) because it is measured under less strict conditions, usually a few hours after a meal.

Key factors that influence an individual's REE include:

• Body Composition: Lean body mass (muscle) is more metabolically active than fat mass, meaning individuals with more muscle burn more calories at rest.
• Age: REE naturally declines with age, primarily due to a reduction in lean muscle mass.
• Sex: Due to differences in body composition (men generally have a higher proportion of lean muscle mass), men typically have a higher REE than women.
• Genetics: Your genetic makeup can influence your natural metabolic rate.
• Medical Conditions: Illnesses like hyperthyroidism or fever can increase REE, while hypothyroidism and starvation diets can decrease it.

What is Total Energy Expenditure (TEE)?

Total Energy Expenditure (TEE), also known as Total Daily Energy Expenditure (TDEE), is the total number of calories your body burns in a 24-hour period. It is a more comprehensive measure than REE because it includes three main components that contribute to your daily calorie burn:

1. Resting Energy Expenditure (REE): The calories needed for baseline bodily functions.
2. Thermic Effect of Food (TEF): The energy used to digest, absorb, and process the nutrients in your food. This typically accounts for about 10% of your total calorie expenditure.
3. Activity Energy Expenditure (AEE): The energy expended during any form of physical activity. This is the most variable component of TEE and includes everything from planned exercise to non-exercise activity thermogenesis (NEAT), like fidgeting or walking.

Comparison Table: REE vs. TEE

Feature	Resting Energy Expenditure (REE)	Total Energy Expenditure (TEE)
Definition	Energy burned at complete rest for basic life functions.	Total calories burned in a 24-hour period, including all activity and digestion.
Components	Sustaining vital organ function, respiration, and circulation.	REE, Thermic Effect of Food (TEF), and Activity Energy Expenditure (AEE).
Variability	Relatively stable and influenced by factors like age, sex, and body size.	Highly variable, dependent on daily physical activity levels and food intake.
Measurement	Measured using indirect calorimetry or estimated with predictive formulas (e.g., Mifflin-St Jeor).	Typically estimated by multiplying REE by an activity factor (PAL).
Primary Use	Establishes a baseline for metabolism; ensures minimum nutritional needs are met.	Determines a person's total daily calorie requirement for weight management.
Contribution to Total	The largest component, usually 60-75%.	The overall sum of all energy expenditures.

How to Calculate and Apply REE and TEE in Nutrition

To effectively manage your weight, you must first understand both REE and TEE. Here's a step-by-step guide:

1. Estimate Your REE: You can use a formula to get an estimate. The Mifflin-St Jeor equation is often recommended for its accuracy. For men: REE = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5. For women: REE = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161.
2. Determine Your Activity Factor (PAL): Select a physical activity level (PAL) based on your lifestyle:
   • Sedentary (little or no exercise): 1.2
   • Lightly Active (light exercise 1-3 days/week): 1.375
   • Moderately Active (moderate exercise 3-5 days/week): 1.55
   • Very Active (hard exercise 6-7 days/week): 1.725
   • Extremely Active (very hard daily exercise): 1.9.
3. Calculate Your TEE: Multiply your estimated REE by your activity factor. This gives you your total daily calorie needs. TEE = REE x Activity Factor.
4. Apply TEE for Weight Goals: Once you have your TEE, you can adjust your calorie intake to achieve your goals:
   • Weight Maintenance: Consume calories equal to your TEE.
   • Weight Loss: Consume fewer calories than your TEE.
   • Weight Gain: Consume more calories than your TEE.

The Role of TEF and Activity in Your Energy Budget

The other two components of TEE—TEF and AEE—are also critical. The Thermic Effect of Food (TEF) is the energy cost of digestion. Protein has a higher TEF than carbohydrates or fats, meaning your body uses more energy to process it. A high-protein diet can therefore slightly increase your overall TEE. Activity Energy Expenditure (AEE) is the most flexible component, which is why increasing physical activity is a highly effective method for changing your TEE and influencing body weight. Even non-exercise activities like fidgeting, walking to your car, or doing household chores contribute to your AEE.

Conclusion

In summary, the key difference between REE and TEE nutrition is their scope: REE is a measure of your baseline, at-rest metabolic needs, while TEE is a holistic measure encompassing all daily energy expenditures, including rest, digestion, and physical activity. By first calculating your REE and then multiplying it by an activity factor, you can accurately estimate your TEE, providing a powerful and personalized tool for managing your nutritional intake. Understanding and leveraging both of these figures is a foundational step toward achieving your specific health and fitness goals. For further information on energy expenditure, the NCBI offers extensive resources.

Frequently Asked Questions

What is the primary difference between REE and TEE?

The primary difference is that REE measures the calories your body needs at complete rest for basic functions, while TEE measures the total calories you burn in a day, including resting, digesting food, and all physical activity.

Why is REE lower than TEE?

REE is lower than TEE because it only accounts for the energy expended while resting. TEE includes REE plus the energy used for physical activity and the digestion of food, making it a higher overall number.

Which is more important for calculating my daily calorie needs?

TEE is the more important number for calculating daily calorie needs for weight management because it provides a complete picture of your total energy expenditure throughout the day, not just at rest.

How is REE measured?

REE is most accurately measured using a lab test called indirect calorimetry, where your oxygen consumption and carbon dioxide production are analyzed. It can also be estimated using predictive equations, like the Mifflin-St Jeor formula.

Does eating food affect REE or TEE?

Eating food does not affect REE, as it is a resting measurement. However, it does affect TEE through the Thermic Effect of Food (TEF), which is the energy required to digest and process the food you eat.

Can I use REE for weight loss?

You should not consume fewer calories than your REE for weight loss, as this can be dangerous. Your REE is the minimum energy your body needs to function. Instead, you should create a calorie deficit relative to your TEE, under the supervision of a doctor if necessary.

How can I increase my REE?

You can increase your REE by building more lean muscle mass through strength training, as muscle tissue is more metabolically active than fat tissue at rest.