Food · lesson 1 of 11
Energy balance — the calorie equation
What a calorie is, where your daily burn comes from, and why counting is an estimate.
6 min read · reviewed October 2026
A calorie (technically a kilocalorie) is just a unit of energy. Eat more energy than you spend and your body stores the surplus, mostly as fat; eat less and it draws on reserves. That balance — energy in versus energy out — is what ultimately governs body weight.
But "weight" and "health" aren't the same thing. Calories decide the direction of the scale; the quality of those calories decides how you feel, perform, and age. You can lose weight on junk and gain it on whole food. This track holds both ideas at once.
Calories govern weight, quality governs health
Energy balance sets whether you gain, hold, or lose. Food quality and macro composition set your body composition, energy, hunger, and long-term health. Optimise both — they answer different questions.
Where your daily burn (TDEE) comes from
Your total daily energy expenditure (TDEE) is everything you burn in a day. It's mostly just being alive, plus a chunk for moving, plus a small cost for digesting food.
How it works →
TDEE = BMR + activity + the thermic effect of food (TEF). BMR (basal metabolic rate) is the energy to keep you alive at rest — heart, brain, kidneys, cell maintenance — and is typically 60–70% of TDEE. Activity splits into deliberate exercise plus NEAT (non-exercise activity thermogenesis: fidgeting, walking, standing) and varies enormously between people. TEF is the energy spent digesting and processing food, roughly 10% of intake — but it's not flat across macros: protein costs ~20–30% of its own calories to process, carbs ~5–10%, fat ~0–3%.
What the studies show →
BMR is estimated with equations like Mifflin-St Jeor from height, weight, age, and sex, then multiplied by an activity factor (~1.2 sedentary to ~1.9 very active). These predictions carry real error — individuals can differ from the estimate by 10–20% — so any calculated number is a starting hypothesis, not a fact. NEAT in particular varies several hundred calories per day between people and adapts when you over- or under-eat, which is part of why the body resists simple energy manipulation.
How many calories does one gram of FAT provide?
Somewhere between 0 and 12 kcal/g.
Reveal the answer →
9 kcal per gram
Fat packs 9 kcal per gram — more than double protein and carbohydrate, which each provide about 4 kcal/g. (Alcohol sits in between at ~7 kcal/g.) This energy density is why a splash of oil or a handful of nuts adds up fast, and why fat is a useful lever for hitting — or trimming — a calorie target.
Which is the LARGEST component of most people's daily calorie burn?
- Deliberate exercise
- The thermic effect of food
- BMR — the cost of just staying alive at rest
- Digestion of protein
Show the answer →
C.BMR — the cost of just staying alive at rest
BMR is typically 60–70% of total daily expenditure. Exercise is usually a smaller, more variable slice than people assume — which is why you can't reliably out-train a poor diet, and why what you eat matters more than most workout plans admit.
Formulate estimates your targets and shows today's intake against them — the fastest way to turn the calorie equation from theory into a habit.