What are maintenance calories, and how do I find mine?
Your maintenance calories are the number of calories you can eat each day without gaining or losing weight. Eat at that number and your weight holds steady. To find yours, work out your BMR (the calories your body burns just staying alive) with the Mifflin-St Jeor equation, then multiply by an activity factor between 1.2 and 1.9 depending on how much you move. That gives your TDEE, and your TDEE is your maintenance number. Here is how to get there step by step.
What maintenance actually means
Every day your body burns a certain amount of energy. Some of it keeps your heart beating, your lungs working and your cells ticking over. Some of it powers walking, typing, fidgeting and exercise. Add all of that up and you get the calories you burn in a day.
Eat exactly that many calories and your weight stays put. Eat fewer and you lose weight. Eat more and you gain. Maintenance is the balance point in the middle.
Knowing your maintenance number is the foundation for everything else. Want to lose weight? Eat below it. Want to build muscle? Eat a little above it. Want to hold steady after a diet? Sit on it. You cannot aim properly until you know where the centre is.
Step one: work out your BMR
BMR stands for basal metabolic rate. It is the energy your body burns at complete rest, doing nothing but staying alive. It is the biggest chunk of your daily burn, usually around 60 to 70% of the total.
The most trusted way to estimate it is the Mifflin-St Jeor equation. It uses your weight in kilograms, height in centimetres and age in years.
For men: BMR = (10 x weight) + (6.25 x height) - (5 x age) + 5
For women: BMR = (10 x weight) + (6.25 x height) - (5 x age) - 161
Take a 30-year-old woman who weighs 70kg and stands 165cm tall:
- 10 x 70 = 700
- 6.25 x 165 = 1,031
- 5 x 30 = 150
- 700 + 1,031 - 150 - 161 = 1,420 kcal
So her body burns roughly 1,420 kcal a day just existing. That is her BMR, but it is not her maintenance number yet, because she does not spend all day lying still.
Step two: add your activity
To get from BMR to the calories you actually burn, you multiply by an activity factor. This accounts for everything you do on top of resting: walking to work, standing, cleaning, training, all of it.
The scale runs from about 1.2 to 1.9:
| Activity level | Factor | Roughly means |
|---|---|---|
| Sedentary | 1.2 | Desk job, little or no exercise |
| Lightly active | 1.375 | Light exercise 1 to 3 days a week |
| Moderately active | 1.55 | Moderate exercise 3 to 5 days a week |
| Very active | 1.725 | Hard exercise 6 to 7 days a week |
| Extra active | 1.9 | Physical job or twice-a-day training |
Multiply your BMR by the factor that fits your week and you get your TDEE: total daily energy expenditure. That is your maintenance number.
Putting it together
Back to our 30-year-old woman with a BMR of 1,420 kcal. Say she has a desk job but gets to the gym three or four times a week. That puts her around moderately active, so a factor of 1.55.
1,420 x 1.55 = 2,201 kcal
So she burns roughly 2,200 kcal a day. That is her maintenance. Eat around that and her weight holds. Drop to 1,700 and she loses. Push to 2,600 and she gains.
If she were sedentary instead, it would be 1,420 x 1.2 = about 1,704 kcal. The activity factor makes a real difference, which is why picking an honest one matters. Most people overrate how active they are.
Treat the number as a starting point
The maths gives you an estimate, not a fixed truth. Two people with identical stats can burn different amounts. The equation gets you close, usually within a couple of hundred calories, and that is close enough to start.
The real test is the scale over time. Eat at your calculated maintenance for two or three weeks and watch the trend. If your weight is drifting up, your true maintenance is a bit lower than the estimate, so nudge your intake down. If it is drifting down, nudge it up. After a few weeks of tracking, you will know your real number better than any equation can tell you.
This is where logging earns its keep. Fettle (stayfettle.com) works out your BMR and TDEE from your details, sets your daily target, and adds up what you eat as you go, so you can compare the estimate against what actually happens on the scale. It has UK foods and barcode scanning, it is free, and there is no account needed.
One honest note
These figures are general guidance, not medical advice. The Mifflin-St Jeor equation suits most healthy adults, but if you have a health condition, are pregnant, or follow a specific eating plan for medical reasons, check with your GP or a registered dietitian before changing how you eat.