Your maintenance calories are the total number of calories your body burns in a full day, often called your Total Daily Energy Expenditure (TDEE). Eat this amount consistently and your weight stays roughly the same. For most adults, this falls somewhere between 1,600 and 3,000 calories per day, depending on your size, age, sex, and how active you are. The only way to find your specific number is to estimate it with a formula, then refine it with real-world tracking.
Where Your Calories Actually Go
Your body burns calories in three main ways, and understanding the split helps explain why two people of the same weight can have very different maintenance numbers.
Your resting metabolic rate (RMR) is the biggest piece, accounting for roughly 60 to 70 percent of everything you burn. This is the energy your body uses just to keep you alive: pumping blood, breathing, maintaining body temperature, running your brain. Even if you stayed in bed all day, this baseline burn would still happen.
Physical activity makes up the second largest share, typically 20 to 30 percent. This includes formal exercise like running or lifting weights, but also all the smaller movements throughout your day: walking to your car, fidgeting, standing while cooking, carrying groceries. That non-exercise movement varies enormously between people and is one reason someone with an active job burns far more than someone at a desk.
The remaining roughly 10 percent goes to digesting food itself. Your body spends energy breaking down, absorbing, and transporting nutrients. Not all foods cost the same to digest, though. Protein requires the most energy, boosting your metabolic rate by 15 to 30 percent of the calories in that food. Carbohydrates cost 5 to 10 percent, and fats cost the least at 0 to 3 percent. This is one reason higher-protein diets can slightly raise your daily burn.
How to Estimate Your Number
The most widely used method is a two-step process: first calculate your resting metabolic rate, then multiply it by an activity factor.
The Mifflin-St Jeor equation is considered the most reliable formula for most people. It uses your weight in kilograms, height in centimeters, and age in years:
- For men: (10 × weight) + (6.25 × height) – (5 × age) + 5
- For women: (10 × weight) – (6.25 × height) – (5 × age) – 161
To convert: divide your weight in pounds by 2.2 for kilograms, and multiply your height in inches by 2.54 for centimeters. A 35-year-old woman who weighs 150 pounds (68 kg) and stands 5’6″ (167.6 cm) would get a resting metabolic rate of about 1,367 calories per day.
If you know your body fat percentage (from a DEXA scan, for example), the Katch-McArdle formula can be more accurate because it accounts for how much of your weight is muscle versus fat. It uses a single equation for everyone: 370 + (21.6 × lean body mass in kg). You calculate lean body mass by subtracting your fat mass from your total weight. This formula is particularly useful for people who are very lean or very muscular, since those body compositions throw off standard equations.
Adjusting for Your Activity Level
Your resting metabolic rate only tells you what you burn at complete rest. To get your actual maintenance calories, you multiply that number by a physical activity level (PAL) factor. These factors, based on long-term research into sustainable activity patterns, range from about 1.4 to 2.4:
- Sedentary or lightly active (PAL 1.4 to 1.69): Desk job, little intentional exercise, mostly sitting or standing during the day.
- Moderately active (PAL 1.7 to 1.99): Regular exercise several times per week, or a job that involves a fair amount of walking or physical tasks.
- Vigorously active (PAL 2.0 to 2.4): Hard daily training, a physically demanding job, or both. Sustaining a PAL above 2.4 over time is extremely difficult for most people.
Using the example above, that 35-year-old woman with a resting rate of 1,367 calories would multiply by 1.55 if she exercises moderately a few times per week. Her estimated maintenance would be about 2,119 calories per day. If she were sedentary, it would drop closer to 1,900. If she trained hard daily, it could reach 2,700 or more.
Most people overestimate their activity level. If you work out three or four times a week but sit for most of your working hours, a multiplier around 1.5 to 1.6 is usually more realistic than the “active” category.
Why Formulas Are Only a Starting Point
No equation will nail your exact number. Prediction formulas can overestimate true energy expenditure by 10 to 15 percent or more, depending on the population studied. Some research has found overestimations as high as 17 to 27 percent when standard methods are compared against laboratory measurements. This means a formula might tell you 2,400 calories when your real maintenance is closer to 2,100.
The practical solution is to use a formula as your starting estimate, eat that amount for two to three weeks, and watch the scale. Weigh yourself under consistent conditions (same time of day, same clothing) and look at the weekly average rather than any single day. If your average weight is stable, you’ve found your maintenance. If it’s trending up, your true maintenance is somewhat lower. If it’s dropping, you’re eating below maintenance.
Adjustments of 100 to 200 calories at a time are enough. Small changes give you cleaner data than large swings.
Factors That Shift Your Maintenance Over Time
Your maintenance calories are not a fixed number. They change as your body and circumstances change, sometimes in ways that aren’t obvious.
Age is the most predictable factor. As you get older, you gradually lose muscle mass, and since muscle is the most metabolically active tissue in your body, your resting burn declines with it. This is why someone eating the same diet at 50 that they ate at 30 may slowly gain weight without any other changes.
Body composition matters independently of weight. Two people who both weigh 180 pounds can have very different maintenance calories if one carries significantly more muscle. Muscle burns more calories at rest than fat does, which is why strength training can meaningfully raise your baseline over time.
Sex plays a role as well. Men typically have more muscle mass and less body fat than women of the same age and weight, which translates to a higher resting metabolic rate.
Environmental temperature can also shift your needs. In very cold or very hot conditions, your body works harder to maintain its core temperature through mechanisms like shivering or sweating. People living in extreme climates or working outdoors may burn noticeably more than indoor estimates suggest.
What Happens After Weight Loss
One of the most important things to understand about maintenance calories is that they drop after you lose weight, and they drop by more than the math alone would predict. When you eat in a calorie deficit for an extended period, your body adapts by becoming more efficient: your resting metabolic rate decreases, you unconsciously move less throughout the day, and the energy cost of movement drops because you’re carrying less mass. This is sometimes called metabolic adaptation.
This means that after losing 20 or 30 pounds, your new maintenance calories will be lower than what a formula would calculate for someone who has always been at that weight. The difference can be a few hundred calories per day, which is enough to cause slow regain if you eat according to a formula alone.
The most reliable way to find your new maintenance after weight loss is the same tracking approach: pick a calorie target, hold it steady, and let two to three weeks of scale data tell you if it’s accurate. Rebuilding or maintaining muscle through resistance training also helps counteract some of this metabolic slowdown by preserving the tissue that drives your resting burn.