Calorie needs formula: work out your maintenance yourself

Your calorie needs are the number of calories you burn per day: your resting metabolism plus everything you move. For an 80 kilo man who trains three times a week, that often sits around 2,700 kcal. Work it out and you have a starting point, not an exact truth.

I see athletes calculate that one number endlessly. Waste of energy. The calculator gives an estimate, your body gives the answer.

How many calories do you need per day?

Most adults sit between 2,000 and 3,000 kcal per day. Your exact number depends on your weight, height, age, sex and how much you move. An active 90 kilo strength athlete burns far more than a 60 kilo office worker. So calculate with your own figures, not with an average.

The Voedingscentrum, the Dutch nutrition authority, keeps about 2,500 kcal for an average man and about 2,000 kcal for an average woman. Those are population guides, not a number for you as an athlete.

Train seriously and your needs sit higher. Movement counts for more than people think.

How do you calculate your calorie needs?

You calculate your calorie needs in two steps. First your resting metabolism (BMR) with the Mifflin-St Jeor formula, then you multiply it by an activity factor (PAL). The result is your total daily energy use, or TDEE. For a man of 80 kilo, 180 cm and 30 years, the BMR is about 1,780 kcal.

The formula by Mifflin and St Jeor (1990) still counts as the most accurate estimate for healthy adults. Your activity factor runs from 1.2 (sedentary) to 1.9 (very heavy activity). Read more about that resting metabolism in our piece on BMR and resting metabolism.

The table below works it out at that BMR of 1,780 kcal.

If you would rather not do the maths, use our calorie needs calculator. It runs the same sum in a few taps.

Why is the calculator not always right?

A calculator gives an estimate with a margin of about 10 percent. Two people with the same weight and the same training can differ by hundreds of calories. Your muscle mass, your hormones and even how restless you sit all play a part. So treat the number as a departure point, not a final stop.

Take two lifters of 85 kilo. One fidgets and moves all day, the other sits still behind a screen. That same little formula puts them on the same number, but their real burn can differ by 300 kcal.

On top of that, your body adapts. Eat less for a while and your burn drops a little. How you adjust a starting number in practice is in our piece on counting and tracking calories.

How many calories for fat loss, maintenance or gaining?

Your goal decides whether you eat below, at or above your calorie needs. For fat loss, take about 300 to 500 kcal less per day. For maintenance, you eat at your needs. To build muscle mass, you sit 200 to 400 kcal higher. Change one knob at a time and give it weeks.

The maintenance number is your anchor. Know it and you simply add or subtract. How to find your maintenance exactly is in how many calories per day you need.

If you want to lose fat but it is not working, more than calories is usually at play. Then read our piece on weight loss and your blood values.

Pick your direction and hold it for a few weeks. Bouncing between bulking and cutting gets you nowhere.

How do you see in your blood whether your metabolism plays along?

Your blood does not directly tell your calorie needs, but it does show whether your metabolism runs normally. A slow thyroid can lower your burn and frustrate your fat-loss efforts. Values like TSH, glucose and HbA1c give context to a number that will not move. Always discuss a deviation with your GP.

If the scale stalls while you do everything right, your thyroid is worth a check. More on that in thyroid and weight.

If you want a starting point, our 360 health blood test measures your thyroid and blood sugar among others. That way you know your base is right before you tinker with calories.

My advice: calculate your calorie needs once, eat at that number for two weeks and weigh yourself. If your weight does not move as expected, adjust by 100 to 200 kcal. That way you steer on real data. The full approach to nutrition around your training is in our plan for muscle growth and recovery.

References

1. Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 1990. PMID: 2305711.
2. Gezondheidsraad. Dietary reference values: energy. 2021.
3. Voedingscentrum. How many calories do I need per day? 2024.

Disclaimer

Every blood test result includes a professional assessment by a BIG-registered doctor. This article gives general information and is not a substitute for medical advice. A blood test is a tool to walk into the conversation with your GP better informed, not a diagnosis in itself. For treatment decisions, discuss your results with your GP.