How to Calculate How Many Calories You Burn in a Day Without Exercise

An estimated 60-75% of your total daily energy expenditure is used simply for basic bodily functions like breathing and blood circulation. Understanding this basal metabolic rate (BMR) is the first step to accurately calculating your total daily calorie burn, even on days with little to no formal exercise.

Quick Summary

This guide outlines the process for estimating your daily calorie burn without formal exercise. It covers the Mifflin-St Jeor formula for determining your basal metabolic rate (BMR) and explains how to adjust this number to reflect your daily activity level, including non-exercise activity thermogenesis (NEAT).

Key Points

• Start with BMR: Your Basal Metabolic Rate (BMR) is the foundation, representing calories burned at complete rest for basic survival functions.

• Use the Mifflin-St Jeor Equation: This formula is widely regarded as one of the most accurate for estimating your BMR based on your sex, age, weight, and height.

• Account for NEAT: Don't forget Non-Exercise Activity Thermogenesis (NEAT), which includes all non-structured movement like standing, walking, and fidgeting.

• Apply the Sedentary Activity Factor: For no-exercise days, multiply your BMR by 1.2 to get your estimated Total Daily Energy Expenditure (TDEE).

• Manage Expectations: Understand that while metabolism is a factor, significant weight changes often relate more to lifestyle habits and diet than a slow metabolism, particularly in mid-adulthood.

• Use Consistent Data: For reliable results, use consistent and accurate measurements for your weight, height, and age when applying the calculation formulas.

Understanding Your Basal Burn: Basal Metabolic Rate (BMR)

Your Basal Metabolic Rate (BMR) is the minimum number of calories your body needs to perform essential, life-sustaining functions at rest. This includes everything from breathing and blood circulation to cell production and temperature regulation. It is the largest component of your daily energy expenditure and forms the foundation for any calorie burn calculation. The closely related term, Resting Metabolic Rate (RMR), is often used interchangeably but can be slightly higher as it accounts for the energy used during low-effort daily activities like eating. For most practical purposes, BMR serves as the reliable starting point.

The Mifflin-St Jeor Equation: A Modern Standard

While older formulas exist, the Mifflin-St Jeor equation is often considered one of the most accurate predictive equations for estimating BMR in modern lifestyles. It takes into account your sex, weight, height, and age to provide a solid baseline figure.

How to use the Mifflin-St Jeor Equation

First, you will need your weight in kilograms, height in centimeters, and age in years. You can perform the calculation using one of the following formulas:

• For Men: $BMR = 10 imes ext{weight (kg)} + 6.25 imes ext{height (cm)} - 5 imes ext{age (y)} + 5$
• For Women: $BMR = 10 imes ext{weight (kg)} + 6.25 imes ext{height (cm)} - 5 imes ext{age (y)} - 161$

For example, a 30-year-old woman, 168 cm tall, and weighing 65 kg would calculate her BMR as: $BMR = 10 imes 65 + 6.25 imes 168 - 5 imes 31 - 161 = 1384$ kcal/day.

Beyond BMR: Accounting for Everyday Movement (NEAT)

While your BMR covers the basics, your day isn't spent in a state of complete rest. The energy you use for non-exercise activities is known as Non-Exercise Activity Thermogenesis (NEAT). This includes all the energy expended for everything that isn't formal exercise, such as:

• Standing up and walking around
• Fidgeting or tapping your feet
• Typing on a keyboard
• Cooking or cleaning
• Shopping or running errands

NEAT can vary significantly between individuals, with some naturally moving more than others, and it accounts for a large portion of daily energy expenditure beyond your BMR.

Calculating Your Total Daily Energy Expenditure (TDEE)

To get a complete picture of your daily calorie burn without formal exercise, you must combine your BMR with an activity factor that includes NEAT. This combined number is your Total Daily Energy Expenditure (TDEE).

Using Activity Multipliers

For a sedentary lifestyle (meaning little to no formal exercise), you can use a conservative activity multiplier.

• Sedentary: Little to no exercise, desk job: Multiply BMR by 1.2.
• Lightly Active: Light exercise/sports 1-3 days/week: Multiply BMR by 1.375.
• Moderately Active: Moderate exercise/sports 3-5 days/week: Multiply BMR by 1.55.
• Very Active: Hard exercise/sports 6-7 days/week: Multiply BMR by 1.725.

For someone calculating their calorie burn without exercise, the 'Sedentary' multiplier of 1.2 is the most appropriate. Taking the example woman's BMR of 1384 kcal, her sedentary TDEE would be: $1384 imes 1.2 = 1660.8$ kcal/day.

Factors Influencing Your Resting Calorie Burn

Your calorie burn isn't static; it's influenced by several factors that the BMR equation already accounts for.

• Age: As people age, metabolism gradually slows, partly due to the natural loss of muscle mass. However, a 2021 study in Science suggests this decline is less dramatic than previously thought, remaining stable between ages 20 and 60.
• Body Composition: Muscle tissue burns more calories at rest than fat tissue. This is why individuals with more lean muscle mass often have a higher BMR.
• Sex: Generally, men have a higher BMR than women due to higher average muscle mass and body size.
• Thyroid Hormones: Conditions like hyperthyroidism can increase BMR, while hypothyroidism can decrease it.
• Dietary Habits: Restrictive dieting or starvation can cause your BMR to slow down as your body attempts to conserve energy. Conversely, adequate protein intake can support a higher metabolic rate.

BMR vs. TDEE for a Sedentary Lifestyle: A Comparison

To solidify the distinction, here is a quick comparison table outlining the two key calculations for someone not engaging in formal exercise.

Feature	Basal Metabolic Rate (BMR)	Total Daily Energy Expenditure (TDEE)
What it Represents	Calories burned at complete rest.	BMR plus calories from all daily activities.
Primary Calculation	Use a formula like Mifflin-St Jeor.	Multiply BMR by an activity factor.
Typical Use Case	Baseline calorie needs, used as the start for TDEE.	Total estimated calorie burn for a given day.
For a Sedentary Person	Represents the bulk of their daily burn.	Represents the total burn, including minor movements.

The Three-Step Calculation Process

1. Calculate Your BMR: Use the Mifflin-St Jeor formula, gathering your weight in kilograms, height in centimeters, and age in years. Choose the appropriate formula for men or women.
2. Determine Your Activity Factor: For calculating calories burned without exercise, the most suitable activity factor is 1.2, representing a sedentary lifestyle.
3. Multiply for TDEE: Multiply your BMR by the sedentary activity factor (1.2) to get your final estimated TDEE. This represents your total daily calorie burn on a non-exercise day.

Example Calculation

• Your Details: A 45-year-old male, 180 cm tall, and weighing 85 kg.
• BMR Calculation: $BMR = 10 imes 85 + 6.25 imes 180 - 5 imes 45 + 5 = 850 + 1125 - 225 + 5 = 1755$ kcal/day.
• TDEE for Sedentary: $TDEE = 1755 imes 1.2 = 2106$ kcal/day.

Conclusion

Calculating how many calories you burn in a day without formal exercise is not as mysterious as it may seem. By understanding the concept of Basal Metabolic Rate and accounting for Non-Exercise Activity Thermogenesis (NEAT) through a reliable activity multiplier, you can arrive at a practical estimate of your Total Daily Energy Expenditure. Using a validated formula like Mifflin-St Jeor provides an accurate starting point, allowing you to manage your health goals effectively. Remember that consistency and a holistic view of your daily activity, even small movements, are key to understanding your true energy needs. For more details on the Mifflin-St Jeor equation and its development, you can consult various health and nutrition resources.

References

Mifflin-St Jeor equation calculator. Omni Calculator. (n.d.). https://www.omnicalculator.com/health/bmr

Calorie Intake and Weight Loss Calculator. NASM Bodyweight Tool. (n.d.). https://www.nasm.org/resources/calorie-calculator

BMR (Basal Metabolic Rate): What It Is & How To Calculate It. Cleveland Clinic. (2024, May 17). https://my.clevelandclinic.org/health/body/basal-metabolic-rate-bmr

Frequently Asked Questions

What is the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is the energy your body burns at complete rest, while TDEE (Total Daily Energy Expenditure) is your BMR plus the calories you burn from all your daily activities, including movement and digestion.

How accurate are online BMR calculators?

Online BMR calculators that use formulas like Mifflin-St Jeor provide a reliable estimate for most people. However, they are not as precise as a clinical test like indirect calorimetry and do not account for individual muscle mass variations.

Can your metabolism be different from someone else's?

Yes, metabolism rates are unique to each individual. Factors like age, sex, weight, height, genetics, and especially body composition (muscle mass vs. fat mass) all influence your metabolic rate.

Does metabolism actually slow down with age?

Research suggests that metabolism remains relatively stable between ages 20 and 60, with a more noticeable decline beginning around age 60. Many people experience midlife weight gain due to other factors like reduced activity and muscle mass loss, not a drastic metabolic crash.

What is NEAT and how does it affect calorie burn without exercise?

NEAT stands for Non-Exercise Activity Thermogenesis and includes all calories burned from non-formal movement, such as walking, fidgeting, and standing. It is a significant component of your daily calorie burn on non-exercise days, included in the TDEE calculation via the activity multiplier.

Does eating spicy food or drinking coffee increase calorie burn?

Yes, stimulants like caffeine and compounds like capsaicin in spicy foods can provide a small and temporary boost to your metabolic rate. However, the effect is modest and should not be relied upon as a primary weight management strategy.

How can I increase my resting calorie burn without exercising?

The most effective way to increase your resting calorie burn is to build and maintain lean muscle mass, as muscle is more metabolically active than fat. While this typically involves strength training, some factors like eating enough protein and getting quality sleep can also help.