Calculator
How it works and when to use it
The calculator first estimates your basal metabolic rate with the Mifflin-St Jeor equation from weight, height, age and sex, then multiplies it by an activity factor to estimate the calories that keep your weight where it is.
To lose or gain it takes away or adds about 7700 kcal per kilogram a week, about 550 kcal a day for half a kilo a week, a rough figure because energy needs fall as weight comes down.
It never goes under 1200 kcal for women or 1500 kcal for men, the lower end of the low-calorie diets in obesity guidelines, and going lower is for medical supervision.
Reference: Mifflin MD, St Jeor ST et al. Am J Clin Nutr 1990;51:241-7 (BMR) × activity factor; ~7700 kcal per kg (3500 kcal/lb, Wishnofsky M. Am J Clin Nutr 1958;6:542-6), an approximation that overstates long-term loss (Hall KD et al. Lancet 2011;378:826-37); floors: 2013 AHA/ACC/TOS obesity guideline, Jensen MD et al. Circulation 2014;129(25 Suppl 2):S102-38 (1200-1500 kcal/day women, 1500-1800 men)
Frequently asked questions
How much can I safely lose a week?
Guidelines usually aim at half a kilo to one kilo a week, the first weeks can be faster because of water loss, then it slows.
Why does weight loss stall even when I stick to the plan?
A lighter body burns fewer calories, so the deficit shrinks over time, recalculating with your new weight and moving more help it go on.
Can I use it in pregnancy or while breastfeeding?
No, needs rise in pregnancy and breastfeeding, and a weight-loss diet is only for your doctor to decide.
Do I need a dietitian?
The calculator gives a starting point, a dietitian fits the plan to your health, medicines and day, especially with diabetes, kidney or heart disease.
Tools you may also need
- Ideal weight calculator The lowest and highest healthy weight for your height, and what to lose or gain.
- Body fat percentage calculator Body fat from a tape measure, and fat mass in kilograms.
- Macro calculator Grams of carbs, protein and fat a day and per meal.
- Water intake calculator Total water a day, and the share to drink.
- Protein calculator Grams of protein a day and per kilogram of your weight.
- Body mass index (BMI) calculator Your BMI, its class and the healthy weight for your height.
Clinic software for this specialty
Try Clinicato for your clinic
These calculators are free here for everyone, and in Clinicato 49 medical tools work inside the patient's file with the "Medical tools" add-on: filled from the visit and the vital signs, with the result added to the visit's plan, next to appointments, prescriptions and invoices.