How many calories you need, worked out.
Calories a day from Mifflin–St Jeor and an FAO activity level, what to take off to lose weight, and why the old 3,500-calorie rule overpromises.
By Suraj Kumar3 min read
A calorie calculator multiplies two things: what your body uses at rest, and how active your days are. Both are estimates, and the page names where each comes from.
At rest.
Resting energy comes from the Mifflin–St Jeor equation of 1990: 10 × kilograms + 6.25 × centimetres − 5 × age, plus 5 for men or less 161 for women. A woman of 35, 165 cm and 65 kg uses about 1,350 kcal a day at rest.
In a day.
That is multiplied by a physical activity level. The FAO/WHO/UNU report on human energy requirements gives 1.53 as an example for a sitting life, 1.76 for an active one and 2.25 for a vigorous one, and those are the page's three answers.
To lose or gain.
The old rule says a kilogram of body weight is about 7,700 kcal, so half a kilogram a week is about 550 kcal a day less. The body uses less as it gets lighter, so real loss slows over time, as Hall and colleagues showed in The Lancet in 2011; the page says so beside the number.
Further reading
- Mifflin and others, A new predictive equation for resting energy expenditure in healthy individuals, Am J Clin Nutr 1990 (opens in a new tab)
- FAO/WHO/UNU, Human energy requirements (2004), energy requirements of adults (opens in a new tab)
- Hall and others, Quantification of the effect of energy imbalance on bodyweight, The Lancet 2011 (opens in a new tab)
Topics: calorie calculator · how many calories should i eat · calories to lose weight · maintenance calories · daily calorie needs
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