Calorie calculator

Your BMR (basal metabolic rate) is what your body burns if you lie still all day: for your heart, your breathing, your brain and your temperature. For most people that is already more than half of everything they burn in a day.

Your TDEE (total daily energy expenditure) is your total burn per day: your BMR plus everything you move, from taking the stairs to your workout, and the energy it takes to digest your food. Eat exactly your TDEE and your weight stays the same. Eat less and you lose weight; eat more and you gain.

We calculate your BMR with the Mifflin-St Jeor equation from 1990. In comparison studies it estimated the resting burn of most adults best among the common equations.

Male: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5

Female: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

We multiply that BMR by an activity factor. These are the factors almost every TDEE calculator uses; they come from a textbook on exercise and nutrition, not from a single study. Example: a 30-year-old man of 180 cm and 80 kg has a BMR of 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 1,780 kcal. If he trains 3 to 5 times a week (factor 1.55), his TDEE is about 2,760 kcal per day.

So do not add your workouts on top of your TDEE: they are already in the factor. If you are torn between two levels, pick the lower one; most people rate themselves as more active than they are.

To lose weight you eat less than your TDEE. The Dutch Nutrition Centre (Voedingscentrum) calls about half a kilo per week a good pace, and advises against eating less than 1,500 kcal per day (women) or 1,800 kcal (men). A deficit of 250 to 500 kcal per day is a common example to start with: you lose weight gradually and keep enough energy to train. A bigger deficit is faster, but harder to stick to and more likely to cost muscle.

If you want to build muscle, eat slightly more than your TDEE, such as 300 kcal, and make sure you get enough protein. Eating more does not build muscle faster, it just makes you heavier faster.

Every equation calculates for an average person. Your real burn can be a few hundred kcal higher or lower. So use the result as a start: eat to your goal for two to three weeks, weigh yourself a few times a week at the same time of day and look at the average. If it goes faster or slower than you want, adjust your goal by 100 to 200 kcal.