What is TDEE and how do you use it?

What TDEE actually means

Total Daily Energy Expenditure is the sum of all the energy your body uses over a 24-hour period. It includes the calories burned keeping you alive, digesting food, moving deliberately, and fidgeting or standing throughout the day. Knowing your TDEE helps you work out how many calories to eat to lose weight, maintain it, or gain weight in a controlled, gradual way.

Rather than a single fixed figure, think of TDEE as a reasonable estimate that fluctuates slightly day to day depending on sleep, stress, activity, and even the weather.

The four components of TDEE

TDEE is typically broken into four parts:

• BMR (Basal Metabolic Rate) – the energy your body needs at complete rest to keep organs functioning, maintain body temperature, and support basic cellular processes. This usually makes up 60-70% of TDEE.
• TEF (Thermic Effect of Food) – the energy used to digest, absorb, and process what you eat. This accounts for roughly 10% of daily expenditure, with protein requiring more energy to digest than fats or carbohydrates.
• EAT (Exercise Activity Thermogenesis) – calories burned through structured exercise, such as running, cycling, or resistance training.
• NEAT (Non-Exercise Activity Thermogenesis) – everything else: walking, fidgeting, standing, household chores, and general movement. NEAT varies enormously between individuals and can significantly affect total calorie burn.

Estimating BMR: the Mifflin-St Jeor equation

Several equations estimate BMR, but the Mifflin-St Jeor equation is one of the most accurate for the general population and is commonly used in nutrition apps and by dietitians.

For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5

For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161

This gives you an estimate of the calories your body needs at rest, before factoring in any movement or activity.

Turning BMR into TDEE with activity multipliers

Once you have your BMR, multiply it by an activity factor that reflects your typical week:

• Sedentary (little to no exercise, desk job): BMR × 1.2
• Lightly active (light exercise 1-3 days/week): BMR × 1.375
• Moderately active (moderate exercise 3-5 days/week): BMR × 1.55
• Very active (hard exercise 6-7 days/week): BMR × 1.725
• Extremely active (physical job plus intense training): BMR × 1.9

Most people overestimate their activity level, so it's worth being honest when choosing a category. A dedicated TDEE calculator, like the one built into Nutari, can do this maths for you and adjust for your specific stats.

Using TDEE to set your calorie target

Once you know your estimated TDEE, you can set a calorie target based on your goal:

• Maintenance: eat roughly at your TDEE to keep your weight stable.
• Fat loss: create a modest deficit, typically 300-500 calories below TDEE, to support gradual, sustainable loss of around 0.25-0.5 kg per week.
• Muscle or weight gain: eat in a small surplus, generally 200-300 calories above TDEE, combined with resistance training to support lean gains rather than excess fat.

Large, aggressive deficits or surpluses are rarely necessary and can be harder to sustain, so starting conservatively tends to work better long term.

Why TDEE is an estimate you need to adjust

No equation can perfectly predict your individual metabolism. Genetics, muscle mass, hormone levels, sleep quality, and even gut health all influence how many calories you actually burn. This means your calculated TDEE might be off by a few hundred calories in either direction.

The most reliable approach is to use the calculator as a starting point, then track your food intake and body weight consistently for two to three weeks. If your weight isn't changing as expected at your target calories, adjust intake up or down by around 100-200 calories and reassess. Tracking with an app makes this process much easier, as it removes the guesswork from logging food and monitoring trends over time.