What is TDEE?

TDEE stands for total daily energy expenditure: every calorie your body burns in a day. It’s your resting burn, plus the cost of digesting food, plus every step and workout. It comes to 1.2 to 1.9 times your resting burn, depending mostly on how much you walk. It’s the number you eat against, and it’s best treated as a range.

Calculators call it TDEE, maintenance calories or your daily burn. They all mean the same thing. What trips people up is that a calculator prints one exact number, like 2,347, when your real burn sits somewhere in a band a few hundred calories wide. The formula behind it lands within 10% of a lab measurement for about four people in five, and the activity level you pick adds its own error.

The simple version

Think of a house’s energy bill. The fridge, the heating and the lights on timers run all day, with or without anyone home. That’s your resting burn. Cooking dinner and running the dryer are the extras. In a body, the always-on part is the biggest line on the bill.

Where the calories go

• Resting burn (BMR). The biggest part of the day. It keeps your heart, brain, liver and kidneys running. Our calculators multiply it by 1.2 for under 5,000 steps a day, up to 1.9 for 12,500 and more, so resting is about 83% of a sedentary day and still more than half of a very active one.
• Digesting food. 5 to 15% of the day, in a 2004 review. Protein costs the most to process.
• Moving. The rest. For most people workouts are the small part, and everyday movement is the big one: standing, walking, fidgeting. In a 2005 study of 20 people who didn’t exercise, the 10 with obesity sat about 2 hours a day longer than the 10 lean ones. Moving like the lean group would burn about 350 more calories a day, the authors estimated.

What to do

• Get your range from the calories from your steps calculator, which starts from your steps instead of a guess at “moderately active”.
• Eat at the middle for four weeks, weigh in most mornings, then measure your real TDEE.