TDEE: the whole calories-out story (and how Burnie simplifies it)
TDEE is every calorie you burn in a day. It has three parts: BMR, food digestion, and movement. Burnie folds movement into one active-calories number and keeps the maths simple.
TDEE means Total Daily Energy Expenditure. In plain words, it is every single calorie your body burns in one whole day. Think of it as your body's total daily bill. If you eat fewer calories than this bill, you lose weight. If you eat more, you gain weight. That is the whole game. The bill has three main parts, and knowing them helps you see where your calories actually go.
The three parts of your daily burn
Your TDEE is made of three parts. First is BMR (Basal Metabolic Rate), the calories you burn just to stay alive, heart pumping, lungs breathing, brain thinking, even if you lie still all day. This is the biggest part, about 60 to 70 percent. Second is the thermic effect of food, or TEF, the calories your body spends digesting what you ate. That is about 10 percent. Third is activity, your walks, chores, stairs, gym, and even little fidgeting. This part swings the most, about 15 percent for very still people up to 50 percent for very active people.
The TDEE components, side by side
TDEE is one fixed number you must calculate exactly.
mostly falsemostly false — explained simply. Your TDEE changes every day. Move more and the activity slice goes up. Eat more protein and TEF rises a little. Build muscle over months and BMR shifts a touch. You do not need a perfect number. A good estimate plus tracking the trend, lighter weeks vs heavier weeks, is enough. That is why Burnie shows your deficit day by day instead of locking in one rigid target.
How Burnie's maths maps to full TDEE
Burnie keeps things simple. Every day it works out your deficit as food_total_kcal minus (bmr + active_calories). So Burnie's 'calories out' is bmr plus active_calories. The bmr number is your big rest slice, about 60 to 70 percent of TDEE. The active_calories number comes from your phone, through Android Health Connect (like Samsung Health), or you can type it in yourself with a manual override. That one number captures your movement, your walks, chores, stairs, gym, all the daily activity and NEAT-like movement in one tidy figure. What about TEF, the digestion slice? Burnie does not add it separately. This is honest, not a trick. TEF is small, around 10 percent, and it roughly follows how much you eat, so leaving it out keeps the maths clean without changing the plan much. Burnie never reads your heart rate, your sleep, your blood pressure, or your location. It is free, with no paid tier and no upsell.
Use the full TDEE picture the easy way
The bottom line
TDEE is your body's whole daily calorie bill, made of BMR (about 60 to 70 percent), TEF (about 10 percent), and activity (15 to 50 percent, the part you can move most). Burnie simplifies this honestly: calories out equals bmr plus active_calories from your phone, and it does not add TEF separately because TEF is small and tracks your food intake. You do not need a perfect TDEE number. Log your food, let your phone fill the movement, and watch the weekly trend. That is the Burnie way.