Most people need to eat 500 fewer calories per day than they burn to lose about half a pound to one pound per week. That means your target isn’t a single magic number that works for everyone. It depends on how many calories your body burns in a day, which varies based on your size, age, sex, and how active you are. The real task is figuring out your personal starting point and subtracting from there.
How Your Body Burns Calories
Your body uses energy in three main ways. The biggest chunk, about 60% to 70% of your total daily burn, goes to basic survival functions: breathing, circulating blood, regulating temperature, and keeping your cells alive. This baseline burn is called your basal metabolic rate, or BMR. Another 10% goes toward digesting and processing the food you eat. The remaining 20% to 30% fuels everything you physically do, from walking to the kitchen to running a 5K.
Add all three together and you get your total daily energy expenditure, or TDEE. This is the number that matters for weight loss. Eat less than your TDEE and your body pulls from stored energy (mostly fat) to make up the difference. Eat more and the excess gets stored.
Estimating Your Daily Calorie Burn
The most reliable way to estimate your BMR without lab equipment is the Mifflin-St Jeor equation. A systematic review in the Journal of the American Dietetic Association found it predicted resting metabolic rate within 10% of the actual measured value more often than any competing formula, across both normal-weight and obese individuals.
Here’s how it works:
- Men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
If you prefer pounds and inches: multiply your weight in pounds by 0.453 to get kilograms, and your height in inches by 2.54 to get centimeters.
Once you have your BMR, multiply it by an activity factor to get your TDEE:
- Sedentary (desk job, little exercise): BMR × 1.2
- Lightly active (light exercise 1 to 3 days per week): BMR × 1.375
- Moderately active (moderate exercise 3 to 5 days per week): BMR × 1.55
- Very active (hard exercise 6 to 7 days per week): BMR × 1.725
- Extremely active (intense training or physical job): BMR × 1.9
For a quick example: a 35-year-old woman who weighs 170 pounds (77 kg), stands 5’5″ (165 cm), and exercises lightly a few times a week would calculate a BMR of roughly 1,440 calories, then multiply by 1.375 to get a TDEE of about 1,980 calories per day. That’s her maintenance level, the amount she’d eat to stay the same weight.
How Big Your Deficit Should Be
Cutting about 500 calories per day from your TDEE typically produces a loss of half a pound to one pound per week. The CDC notes that people who lose at this gradual, steady pace of 1 to 2 pounds per week are more likely to keep the weight off than those who lose faster. For the woman in the example above, that would mean eating roughly 1,480 calories per day.
You can create this deficit through eating less, moving more, or a combination of both. Splitting the difference often feels more sustainable: trimming 250 calories from your plate and burning an extra 250 through activity, for instance, is less restrictive than doing it all through food.
There is, however, a floor you shouldn’t go below. Harvard Health Publishing advises that women should not eat fewer than 1,200 calories per day and men should not go below 1,500 unless supervised by a health professional. Dropping too low risks nutrient deficiencies, muscle loss, and hormonal disruption that can actually stall your progress.
Why the Number Changes Over Time
One of the most frustrating parts of weight loss is that the calorie target you start with won’t work forever. As you lose weight, your body burns fewer calories at rest because there’s simply less of you to maintain. You also lose some muscle along with fat, and muscle tissue burns more energy than fat tissue does. The result is a slower metabolism at your new, lower weight.
This is exactly what causes the well-known weight loss plateau. You’re eating the same number of calories that produced steady loss in the first months, but your smaller body now burns fewer calories, and eventually intake and expenditure match up. At that point, you’ll need to either reduce calories slightly further (without going below the safety floor), increase physical activity, or both. Recalculating your TDEE every 10 to 15 pounds lost keeps your target accurate.
What You Eat Matters, Not Just How Much
A calorie deficit is the mechanical requirement for weight loss, but what fills those calories makes a significant difference in how hungry you feel, how much muscle you keep, and whether you can actually stick with it. The 2025-2030 Dietary Guidelines for Americans emphasize whole, nutritious foods while limiting highly processed foods, added sugars, and refined carbohydrates.
Protein deserves special attention. Researchers at the University of Kansas Medical Center recommend getting 20% to 30% of your calories from protein when you’re trying to lose weight. In more concrete terms, that means increasing intake from the standard 0.8 grams per kilogram of body weight to about 1.0 to 1.2 grams per kilogram. For someone who weighs 175 pounds, that works out to roughly 80 to 96 grams of protein per day. Higher protein intake helps preserve muscle mass during a deficit, which in turn helps protect your metabolic rate. It also keeps you fuller for longer, making the whole process more tolerable.
Putting It All Together
The practical steps are straightforward. First, estimate your BMR using the Mifflin-St Jeor equation (or use any online calculator that applies it). Second, multiply by the activity factor that honestly reflects your lifestyle. Most people overestimate their activity level, so when in doubt, round down. Third, subtract 500 calories from that total. That’s your daily target.
Track your intake for at least two weeks and compare it against what the scale actually does. If you’re losing half a pound to a pound per week, you’ve found the right number. If nothing’s moving, your TDEE estimate may have been too high, and you’ll want to trim another 100 to 200 calories or add activity. If you’re losing more than two pounds per week consistently (beyond the first week or two, when water weight drops quickly), you’re likely cutting too aggressively. The goal is a pace you can maintain for months, not a sprint that burns out in weeks.