What is TDEE?: The Essentials Behind Your Daily Burn

Written by

Kagetora Kevin Miyamoto

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Ever wondered why some people can indulge in pizza regularly without gaining weight, while others feel like they gain weight just by looking at a slice? The key often lies in each person’s unique daily calorie target, closely tied to something called Total Daily Energy Expenditure (TDEE). But have you ever questioned how meal-tracking apps—like FoodEye, MyFitnessPal, or FatSecret—determine the ideal calorie targets for you based on TDEE? In this article, we’ll dive into how these apps estimate your daily calorie needs using TDEE, why these numbers might not always be accurate, and how you can practically use this knowledge to better achieve your nutrition and fitness goals. Ready to unpack this?

1. What Exactly is TDEE?

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Your Total Daily Energy Expenditure (TDEE) is composed of three primary components:

  • Basal Metabolic Rate (BMR): Calories burned at rest—breathing, heartbeat, maintaining body temperature, etc.
  • Physical Activity: Calories used during planned exercise and everyday movements like walking, standing, and even fidgeting.
  • Thermic Effect of Food (TEF): Energy required to digest and process the food you consume.

Professionals typically calculate BMR using equations like the Harris-Benedict Equation[1] (first published in 1918, revised in 1984) or the Mifflin-St Jeor Equation[2] (published in 1990). After calculating BMR, it’s multiplied by an activity factor (sedentary to highly active) to estimate TDEE.

2. How Meal-Tracking Apps Estimate Your Calories

Apps such as MyFitnessPal, FatSecret, and the upcoming FoodEye typically use similar methodologies to estimate your daily calorie goals:

  • Personal Details: Age, height, weight, and gender are used to calculate your BMR with equations like Mifflin-St Jeor.
  • Activity Levels: You choose an activity level (sedentary, lightly active, moderately active, very active), which multiplies your BMR to give your TDEE estimate.
  • Your Goals: Depending on your weight-loss, maintenance, or gain goals, the app will recommend a calorie deficit or surplus, typically ranging from ±250 to ±500 kcal/day.

For example, if your calculated TDEE is 2,500 calories and your goal is weight loss, the app might recommend around 2,000 calories daily to safely lose approximately 0.5 kg (1 lb) per week.

3. Why App Estimates Aren’t Always Perfect

Although these estimates provide an excellent starting point, they aren’t perfect. Research has shown that even the best formulas can deviate from real-world calorie burn, as measured by methods like indirect calorimetry[3]. Key factors causing variation include:

  • Body Composition: More muscle equals higher calorie burn at rest.
  • Genetics & Hormones: Individual metabolic rate variations influenced by genetics and hormonal fluctuations.
  • Daily Movement Variability: Your actual activity may differ day-to-day from the initial chosen “activity level.”
  • Adaptive Thermogenesis: Your metabolism may decrease slightly during dieting, or temporarily rise when you overeat[4].

4. Real-Life Tracking Makes the Difference

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This is exactly why real-world meal tracking—like logging your food intake using FoodEye’s simple, photo-based method—can dramatically enhance accuracy:

  • Photo Logging: Quick and intuitive visual records of meals help monitor portions and consistency without cumbersome calorie-counting.
  • Easy Adjustments: Spot patterns, adjust portions, or tweak activity levels based on real-world observations.

5. Fine-Tuning Your Approach

Photo by Lindsay Henwood on Unsplash

Regularly monitoring your progress—like weekly weigh-ins, progress photos, or noticing energy levels—allows you to refine your calorie intake. If results stall, slightly decrease intake or add more movement. Losing weight too quickly or feeling low-energy? Gradually add calories back or reduce exercise intensity.

6. Final Thoughts

TDEE calculators—used by popular meal-tracking apps—provide valuable starting points for your calorie targets. But remember, they’re not infallible. Think of TDEE as your compass, not your GPS. Combining these estimates with real-world meal tracking, like with FoodEye, helps you discover your unique calorie needs, making your fitness goals realistic and achievable.

Note: This post is informational only and does not replace medical advice. Consult a professional for personalized guidance.

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