What TDEE is made of
TDEE, total daily energy expenditure, is the calories you burn in a day. It has four parts:
- BMR: the energy to keep you alive at rest, usually the biggest share
- Thermic effect of food: energy used to digest, about 10% of intake
- Exercise: planned workouts
- NEAT: everything else, from walking to fidgeting
The two main formulas
Mifflin-St Jeor (1990), using weight in kg, height in cm and age in years:
- Men: 10 x weight + 6.25 x height - 5 x age + 5
- Women: 10 x weight + 6.25 x height - 5 x age - 161
Katch-McArdle uses lean body mass instead: 370 + 21.6 x lean mass in kg. It can be more accurate if you know your body fat percentage reliably.
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- Your body burns energy even at rest. That's your BMR: about 1,528 kcal a day for a 35-year-old woman who is 5 ft 6 in and 180 lb.
- Daily movement multiplies it. Light activity is × 1.375, so 1,528 becomes about 2,101 kcal. That's your TDEE.
- Eat about 500 kcal less than your TDEE and you're in a deficit: around 1,601 kcal a day.
- That's roughly 1 lb a week at first. Loss slows as your body adapts, so treat the number as a starting point and adjust.
Activity multipliers
| Level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little exercise | 1.2 |
| Lightly active | Light exercise 1 to 3 days a week | 1.375 |
| Moderately active | Moderate exercise 3 to 5 days a week | 1.55 |
| Very active | Hard exercise 6 to 7 days a week | 1.725 |
| Extra active | Physical job plus hard training | 1.9 |
Most people overestimate their activity. If unsure, pick the lower level and adjust after a few weeks of tracking.
A worked example
A 40-year-old woman, 5 ft 5 in (165 cm) and 180 lb (81.6 kg):
- BMR = 10 x 81.6 + 6.25 x 165.1 - 5 x 40 - 161 = about 1,487 calories
- Sedentary TDEE = 1,487 x 1.2 = about 1,785 calories
- Moderately active TDEE = 1,487 x 1.55 = about 2,305 calories
If she knew her body fat was 35%, Katch-McArdle would give a BMR of about 1,516, close to the Mifflin result. Run your own numbers in the TDEE calculator, which shows the formula with your values filled in.
Why calculators disagree
Studies comparing Mifflin-St Jeor with measured resting energy found it was usually within about 10% for most people, but less accurate for some, including people with obesity. Add a guessed activity level and two calculators can easily differ by 200 to 300 calories.
Treat any result as a starting point. Track your weight trend for 2 to 4 weeks, then adjust.
Adjusting after 3 weeks
Your weight trend is the best test of any estimate. After 2 to 4 weeks of steady eating and tracking:
| What your trend shows | What it suggests | Try |
|---|---|---|
| Weight steady | You're eating near your TDEE | Use your average intake as your TDEE |
| Losing about 1 lb a week | About a 500-calorie daily deficit | Your TDEE is roughly intake plus 500 |
| Losing much faster than planned | Your TDEE is higher than estimated, or water loss | Give it another 2 weeks before changing |
| Gaining | Intake is above TDEE, or logging misses some food | Recheck portions and drinks first |
The first week of any new plan often shows a quick drop from water and stored carbohydrate, so don't judge your TDEE on week 1 alone. Log weights in the weigh-in tracker to see the trend line.
TDEE on a GLP-1
A GLP-1 doesn't meaningfully change your TDEE; it changes how much you eat. The risk is eating far below your needs. The GLP-1 TDEE calculator shows a sensible floor, and the protein calculator keeps muscle in view.
Run the numbers
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Common questions
What is the most accurate TDEE formula?
Mifflin-St Jeor is the most widely validated for the general population. Katch-McArdle can be better if you know your lean body mass accurately.
Why is my TDEE different on every calculator?
Different formulas and activity multipliers give different answers, and the activity guess alone can swing the result by hundreds of calories.
How do I find my real TDEE?
Eat a consistent, tracked amount for 2 to 4 weeks and watch your weight trend. If weight is steady, your intake is close to your TDEE.