Why does weight loss plateau after several weeks in a deficit?

As you lose mass, your BMR decreases (a smaller body requires fewer calories to run). Additionally, your subconscious NEAT tends to drop to conserve energy. Recalculating your TDEE every 4 to 5 kilograms lost gets progress moving again.

Does 3,500 calories always equal one pound of fat?

The classic 'Wishnofsky rule' assumes pure fat tissue loss, but in reality weight lost consists of a mix of adipose tissue, water, glycogen, and some lean mass. Weight loss is rarely a smooth, linear mathematical slope.

Is it better to create a deficit through diet or cardio?

A combination works best. Creating the entire deficit through exercise is exhausting (running 5 km burns only about 300 kcal), while creating it purely through extreme food restriction can lead to micronutrient deficiencies. A 300 kcal dietary reduction paired with 200 kcal of light daily activity is easier to sustain long-term.

How to calculate TDEE and set a safe calorie deficit

Health7 min readPublished 23 September 2026

Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour cycle. Every weight-management strategy — whether fat loss, muscle gain, or weight maintenance — depends on where your daily calorie intake sits relative to this single baseline number.

This guide breaks down the four physiological components of energy expenditure, works through the standard BMR formula by hand, and explains how to establish a sustainable calorie deficit without triggering muscle loss or severe metabolic adaptation.

The four components of energy expenditure

People often equate 'burning calories' with exercise, but deliberate workouts account for the smallest fraction of daily energy use for most non-athletes. Your TDEE is split into four distinct buckets:

Basal Metabolic Rate (BMR, ~60–70%): The baseline energy needed to sustain involuntary vital functions (cellular respiration, heartbeat, brain function, liver metabolism) at complete rest.
Non-Exercise Activity Thermogenesis (NEAT, ~15–20%): Calories burned during unconscious daily movement — walking to work, fidgeting, typing, climbing stairs, cleaning.
Thermic Effect of Food (TEF, ~8–10%): The metabolic cost of chewing, digesting, absorbing, and storing nutrients. Protein has the highest TEF (20–30% of its calories are burned during digestion), while fats and refined carbohydrates require only 2–5%.
Exercise Activity Thermogenesis (EAT, ~5–10%): Structured workouts, sports, and cardio sessions.

Calculating BMR using the Mifflin-St Jeor equation

Clinical nutrition relies predominantly on the Mifflin-St Jeor formula, recognized as the most accurate estimation tool for individuals without clinical metabolic disorders:

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

Worked example: A 30-year-old male weighing 80 kg and standing 178 cm tall has a BMR of (10 × 80) + (6.25 × 178) − (5 × 30) + 5 = 800 + 1,112.5 − 150 + 5 = 1,767.5 kcal/day. That is what his body burns simply staying alive in bed.

Activity multipliers and TDEE

To translate BMR into TDEE, multiply by a Physical Activity Level (PAL) factor. The most common mistake is overestimating activity — an hour of lifting weights three times a week does not make a sedentary desk worker 'very active'.

Activity Level	Multiplier	Description
Sedentary	1.2	Desk job, little to no structured exercise, under 5,000 steps/day
Lightly active	1.375	Desk job with 1–3 light workout sessions or 6,000–8,000 daily steps
Moderately active	1.55	3–5 moderate workouts per week or active job (teacher, server)
Very active	1.725	6–7 heavy workouts per week or manual construction labor

When in doubt, start with the lower activity bracket. It is far easier to adjust calories upward after two weeks of tracking than to wonder why weight isn't moving.

How to set a sustainable deficit

Determine your baseline TDEE using our Calorie Calculator.
Target a modest deficit of 15% to 20% below TDEE (typically 300 to 500 kcal/day). This yields roughly 0.3 to 0.6 kg of fat loss per week.
Keep protein intake at 1.6 to 2.2 grams per kilogram of body weight to prevent muscle breakdown while in a calorie deficit.
Never drop below your raw BMR for extended periods without medical supervision. Extreme deficits trigger biological starvation defenses: spontaneous NEAT plummets, hunger hormones surge, and sleep quality degrades.

Frequently asked questions

Why does weight loss plateau after several weeks in a deficit?: As you lose mass, your BMR decreases (a smaller body requires fewer calories to run). Additionally, your subconscious NEAT tends to drop to conserve energy. Recalculating your TDEE every 4 to 5 kilograms lost gets progress moving again.
Does 3,500 calories always equal one pound of fat?: The classic 'Wishnofsky rule' assumes pure fat tissue loss, but in reality weight lost consists of a mix of adipose tissue, water, glycogen, and some lean mass. Weight loss is rarely a smooth, linear mathematical slope.
Is it better to create a deficit through diet or cardio?: A combination works best. Creating the entire deficit through exercise is exhausting (running 5 km burns only about 300 kcal), while creating it purely through extreme food restriction can lead to micronutrient deficiencies. A 300 kcal dietary reduction paired with 200 kcal of light daily activity is easier to sustain long-term.