Maintenance calories are the total number of calories your body burns in a day, the amount you’d need to eat to keep your weight exactly where it is. Eat more than this number consistently and you gain weight; eat less and you lose it. For most adults, maintenance falls somewhere between 1,800 and 3,000 calories per day, though the exact number depends on your size, age, body composition, and how active you are.
Understanding this number gives you a starting point for any goal, whether that’s losing fat, building muscle, or simply eating in a way that keeps you feeling steady.
Where Your Calories Actually Go
Your body spends energy on three main things, and they’re not equally demanding.
Resting metabolism is the biggest piece by far, accounting for 60 to 70 percent of everything you burn. This is the energy it takes just to stay alive: keeping your heart beating, your lungs expanding, your brain running, your cells dividing. Even if you stayed in bed all day, this baseline cost would still exist. Your brain and internal organs are especially expensive to run, burning 15 to 40 times more energy per pound than muscle tissue does.
Physical activity is the most variable piece. For someone who sits at a desk most of the day, movement might account for only 15 percent of total calorie burn. For a very active person, it can climb to 50 percent. This includes everything from formal exercise to fidgeting, walking to the kitchen, and standing at your desk.
Digesting food takes about 10 percent of your daily calories. Your body has to break down, absorb, and process everything you eat, and that costs energy. Not all foods are equal here: protein costs the most to digest (20 to 30 percent of the calories in protein get used up just processing it), carbohydrates cost a moderate amount (5 to 10 percent), and fat is the cheapest to process (0 to 3 percent). This is one reason high-protein diets can have a slight metabolic edge.
How to Estimate Your Number
The most common approach is a two-step process: first estimate your resting metabolism, then multiply it by an activity factor.
The Mifflin-St Jeor equation is the formula most recommended by dietitians today. A systematic review comparing the four most widely used equations found it was the most reliable, predicting resting metabolism within 10 percent of the actual measured value more often than any competing formula. Here’s how it works:
- Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
That gives you your resting calorie burn. To get your full daily total, multiply the result by an activity factor:
- Sedentary (desk job, little exercise): multiply by 1.4 to 1.5
- Lightly active (some walking and standing): multiply by 1.6 to 1.7
- Moderately active (standing or walking job, regular workouts): multiply by 1.8 to 1.9
- Very active (heavy physical work or intense daily training): multiply by 2.0 to 2.4
So a 35-year-old woman who weighs 68 kg (150 lbs), stands 165 cm (5’5″), and exercises a few times a week would calculate: (10 × 68) + (6.25 × 165) − (5 × 35) − 161 = roughly 1,380 calories at rest. Multiplied by 1.6 for light activity, her estimated maintenance comes to about 2,200 calories per day.
Keep in mind that any formula is an estimate. The Mifflin-St Jeor equation can be less accurate for older adults and certain ethnic groups, and most people misjudge their activity level (usually overestimating it). Treat the number as a starting point, not a verdict.
Finding Your True Maintenance by Tracking
Calculators get you in the ballpark. To find your actual maintenance calories, you need a few weeks of real-world data.
The process is straightforward. Weigh yourself every morning under the same conditions (after using the bathroom, before eating) and track your food intake as accurately as you can for two to three weeks. Look at the weekly trend in your weight, not daily fluctuations, since water, salt, and digestion can swing the scale by a pound or two on any given day. If your average weight stays stable over two to three weeks, the average number of calories you ate during that period is very close to your true maintenance.
If your weight is drifting up, your maintenance is slightly below what you’ve been eating. If it’s drifting down, you’re eating below maintenance. Adjust by 100 to 200 calories and observe for another week or two. This trial-and-error process takes patience, but it gives you a personalized number that no equation can match.
Why Maintenance Calories Change Over Time
Your maintenance number isn’t fixed. It shifts with your life circumstances, and a few factors matter more than people realize.
Age
A landmark 2021 study published in Science tracked energy expenditure across more than 6,400 people and found that metabolism doesn’t slow down when most people think it does. From age 20 to about 60, adjusted metabolic rate holds remarkably steady. The real decline begins around age 60, dropping at roughly 0.7 percent per year after that. So if you’re in your 30s or 40s blaming a “slowing metabolism” for weight gain, the more likely culprit is reduced activity or gradual changes in eating habits.
Body Composition
A pound of muscle burns roughly 5 to 7 calories per day at rest. A pound of fat burns far less, about 50 to 100 times less per pound than your organs do. Gaining muscle does raise your resting metabolism, but the effect is modest. Adding 10 pounds of muscle might increase your resting burn by 50 to 70 calories daily. The bigger payoff from strength training is the calories burned during the workout itself and the recovery afterward.
Weight Loss History
This one catches people off guard. After losing 10 percent or more of your body weight, your daily calorie burn drops by 20 to 25 percent. Part of that is expected because a smaller body needs less fuel. But 10 to 15 percent of the decline goes beyond what the change in body size explains. This is metabolic adaptation: your body becomes more efficient to resist further weight loss. In practical terms, someone who has lost significant weight needs about 300 to 400 fewer calories per day to maintain the same weight as someone who was never heavier. This adaptation is one of the main reasons weight regain is so common, and it means recalculating your maintenance after any major weight change is essential.
Putting the Number to Use
Once you have a solid maintenance estimate, it becomes the anchor for your nutrition. To lose fat at a moderate, sustainable pace, eating 300 to 500 calories below maintenance per day produces roughly half a pound to one pound of loss per week. To gain muscle, a surplus of 200 to 300 calories above maintenance supports growth without excessive fat gain.
Your maintenance number also helps explain plateaus. If you’ve been dieting for months and progress has stalled, your maintenance has likely shifted downward through a combination of lower body weight and metabolic adaptation. A period of eating at your new maintenance for a few weeks can help reset hunger signals and give you a more accurate baseline before continuing.
The most useful thing about knowing your maintenance calories isn’t precision. It’s perspective. It gives you a framework to understand why your weight is doing what it’s doing, and a concrete lever to adjust when you want it to change.