How it works
First we calculate your resting energy with the Mifflin–St Jeor formula — this is the energy your body uses at complete rest. Then we multiply it by your activity level. The result is your maintenance: the calories that keep your weight stable.
For fat loss we subtract 5–20%, for muscle gain we add 5–15%. Smaller changes are easier to keep up and protect your muscles. We never go below 1500 kcal for men and 1200 kcal for women.
Protein, fat and carbs
- Protein: 1.6 g per kg of body weight to keep weight, 1.8 g to gain muscle and 2.0 g during fat loss (ISSN guidelines).
- Fat: about 27% of calories, but not less than 0.6 g per kg — fat is needed for hormones.
- Carbs: the rest. They are the main fuel for training.
How to use the result
Eat at this level for 2–3 weeks and weigh yourself 3 times a week in the morning. If the average weight does not change in the direction you want, adjust by 100–200 kcal. A safe pace of fat loss is 0.5–1% of body weight per week.
Questions and answers
How many calories do I need to lose weight?
Usually 10–20% less than your maintenance. For most people this is 300–500 kcal a day less. The calculator shows your number and the expected weekly change.
How accurate is the calculator?
Formulas give a good starting point, usually within about 10% for most people. Your real needs show in practice: track your weight for 2–3 weeks and adjust.
Do I have to count macros?
No. If counting is hard, keep two rules: eat enough protein every day and keep calories close to the target. Fat and carbs can vary.
Is the calculator suitable for teenagers?
No. It is made for adults. Teenagers need extra energy for growth, so their needs should be discussed with a doctor or coach.
How it is calculated: sources
- Mifflin MD, St Jeor ST et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51:241–247.
- Jäger R et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.
- EFSA Panel on Dietetic Products. Scientific Opinion on Dietary Reference Values for water. EFSA Journal. 2010;8(3):1459.
Gymvert gives general information for healthy adults. It is not medical advice. If you have a health condition, are pregnant, or are unsure, talk to a doctor before changing your training or diet.