I spent three months eating 1,500 calories a day and barely lost any weight. Turns out, my TDEE was about 2,800 calories — meaning a 1,500-calorie diet was a 46% deficit, which my body interpreted as starvation. My metabolism cratered, I felt terrible, and I was actually gaining fat while losing muscle.
The fix was stupidly simple: calculate my TDEE properly, eat at a moderate 20% deficit (about 2,240 calories), and the weight came off steadily without feeling like death. Here's everything I wish I'd known from the start.
What is TDEE?
TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in a single day. It includes everything:
- BMR (Basal Metabolic Rate) — calories burned just keeping you alive: breathing, pumping blood, maintaining body temperature. This accounts for 60-70% of your TDEE.
- TEF (Thermic Effect of Food) — calories burned digesting food. About 10% of your TDEE. Protein has the highest thermic effect (~25%), meaning a quarter of the calories from protein are burned just digesting it.
- NEAT (Non-Exercise Activity Thermogenesis) — calories burned through daily movement that isn't formal exercise: walking, fidgeting, standing, doing chores. This varies hugely between people and can account for 15-50% of TDEE.
- EAT (Exercise Activity Thermogenesis) — calories burned during intentional exercise. Surprisingly, this is usually the smallest component — maybe 5-10% for most people.
When you see your TDEE number, it represents all four of these combined.
How to calculate your TDEE
You can calculate TDEE in three steps using a TDEE calculator:
Step 1: Calculate your BMR
The most common formula is the Mifflin-St Jeor equation:
- Men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) + 5
- Women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) – 161
Example: A 30-year-old man who weighs 80 kg and is 180 cm tall has a BMR of about 1,780 calories.
Step 2: Multiply by your activity level
Your BMR is what you'd burn lying in bed all day. Multiply it by an activity factor to get your TDEE:
- Sedentary (desk job, no exercise): BMR × 1.2
- Lightly active (exercise 1-3 days/week): BMR × 1.375
- Moderately active (exercise 3-5 days/week): BMR × 1.55
- Very active (exercise 6-7 days/week): BMR × 1.725
- Extremely active (physical job + daily exercise): BMR × 1.9
Our example guy with a BMR of 1,780 who exercises 3 times a week would have a TDEE of about 2,760 calories.
Step 3: Adjust for your goal
- Lose weight: eat 15-25% below TDEE
- Maintain weight: eat at TDEE
- Gain muscle: eat 10-15% above TDEE
A 20% deficit for our example: 2,760 × 0.80 = 2,208 calories per day. That's a deficit of about 550 calories per day, which works out to roughly 1 pound of fat loss per week. Sustainable, healthy, and you won't feel like you're starving.
Why TDEE matters more than arbitrary calorie targets
The biggest mistake I see people make is picking a calorie target out of thin air. "I'll eat 1,200 calories because that's what the magazine said." But 1,200 calories for a 5'10" active man is a 60% deficit — that's a crash diet, and your body will fight it with everything it has.
TDEE gives you a personalized number. A 5'2" sedentary woman and a 6'1" active man have vastly different energy needs. Eating the same number of calories makes no sense for them.
The right deficit is one you can maintain for months without misery. For most people, that's 15-25% below TDEE. Any more aggressive and you risk:
- Muscle loss — your body burns muscle for energy when the deficit is too large
- Metabolic adaptation — your body reduces BMR to conserve energy, making further weight loss harder
- Hormonal disruption — thyroid, testosterone, and leptin levels drop with extreme diets
- Binge cycles — extreme restriction leads to binge eating, which leads to guilt, which leads to more restriction
TDEE and macros
Once you have your calorie target, the next question is what to eat. This is where macros come in. A common starting point:
- Protein: 0.8-1g per pound of body weight (the most important macro for preserving muscle during a cut)
- Fat: 25-30% of total calories (essential for hormones)
- Carbs: whatever's left (fuel for workouts and daily activity)
You can calculate your exact macro split with a macro calculator after you know your TDEE-based calorie target.
How accurate is TDEE?
Honest answer: it's an estimate, not a measurement. The activity multipliers are averages, and individual variation is real. Two people with the same height, weight, age, and exercise routine can have TDEEs that differ by 300+ calories due to genetics, NEAT differences, and metabolic efficiency.
Use your calculated TDEE as a starting point. Weigh yourself under consistent conditions (same time, same clothes) for two weeks while eating at your target calories:
- Losing weight too fast (more than 1-1.5 lbs/week) → eat slightly more
- Not losing weight → eat slightly less (reduce by 100-200 calories)
- Losing at a steady, comfortable rate → you've found your actual TDEE
The calculator gets you to the right neighborhood. Two weeks of tracking gets you to the right house.
Related calculators
- TDEE Calculator — calculate your total daily energy expenditure
- BMR Calculator — find your basal metabolic rate
- Calorie Calculator — daily calorie needs based on your goals
- Macro Calculator — protein, carbs, and fat targets based on your calories
Start with TDEE, set a moderate deficit, track for two weeks, and adjust. It's not sexy, it's not fast, and it won't sell magazines. But it works — consistently and sustainably.