Most people need to eat 500 fewer calories than their body burns each day to lose about one pound per week. That means your target isn’t a single magic number that works for everyone. It depends on your current weight, height, age, sex, and how active you are. The real starting point is figuring out how many calories your body uses just to maintain your current weight, then subtracting from there.
Find Your Maintenance Calories First
Before you can set a weight loss target, you need to estimate how many calories your body burns in a typical day. This number, often called your Total Daily Energy Expenditure, includes everything from keeping your heart beating to walking around the grocery store. It has two main components: the calories your body burns at rest (your resting metabolic rate) and the calories you burn through movement and activity.
The most reliable way to estimate your resting metabolic rate at home is the Mifflin-St Jeor equation. A systematic review in the Journal of the American Dietetic Association compared the most commonly used formulas and found that Mifflin-St Jeor predicted resting metabolic rate within 10% of the actual measured value more often than any other equation, with the narrowest margin of error. Here’s how it works:
- For men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
- For women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
That gives you the calories your body burns doing absolutely nothing. To get your total daily burn, multiply the result by an activity factor: 1.2 if you’re mostly sedentary, 1.375 if you exercise lightly a few times a week, 1.55 for moderate exercise three to five days a week, and 1.725 if you’re highly active most days. The final number is roughly how many calories you need to stay at your current weight.
As a quick example, a 40-year-old woman who weighs 170 pounds (77 kg), stands 5’5″ (165 cm), and exercises a few times a week would have a resting metabolic rate around 1,400 calories. Multiply by 1.375 for light activity and her maintenance level lands near 1,925 calories per day.
How Big Your Deficit Should Be
Once you have your maintenance number, weight loss comes down to consistently eating below it. The CDC recommends losing one to two pounds per week, noting that people who lose weight at this gradual, steady pace are more likely to keep it off than those who drop weight faster. To hit that range, you need a daily deficit of roughly 500 to 1,000 calories.
For the woman in our example, a 500-calorie deficit would mean eating around 1,425 calories per day. A 1,000-calorie deficit would drop her to about 925, which is too low for most people to sustain safely or get adequate nutrition. This is why a 500-calorie daily deficit is the more common and practical starting point for most people. It’s aggressive enough to produce visible results but moderate enough that you’re not constantly hungry or missing essential nutrients.
You don’t have to create the entire deficit through eating less, either. A combination of eating slightly less and moving slightly more often feels more sustainable. Cutting 300 calories from food and burning an extra 200 through a daily walk gets you to the same 500-calorie gap.
Why the “3,500 Calories Per Pound” Rule Falls Short
You’ve probably heard that cutting 3,500 calories equals one pound lost. That old rule gives a useful starting estimate, but it oversimplifies what actually happens in your body. When you lose weight, you lose a mix of fat, lean tissue, and water, not pure fat. The ratio changes over time, which means your rate of loss won’t stay perfectly linear.
Your body also adjusts its energy use as you get lighter. A person who drops from 220 pounds to 198 pounds might expect their daily energy needs to fall to around 2,200 calories, but researchers measuring actual expenditure in metabolic chambers have found the real number can dip closer to 2,000. That gap, sometimes called metabolic adaptation, tends to be most pronounced right after weight loss. When researchers give participants about a month to stabilize after losing weight, that adaptation shrinks dramatically, averaging only a few dozen extra calories per day below what you’d predict from the new body weight alone.
The practical takeaway: your calorie target isn’t something you set once and forget. As you lose weight, your body needs fewer calories to function, so you’ll need to recalculate every 10 to 15 pounds lost or roughly every couple of months.
What You Eat Changes How Many Calories You Actually Absorb
Not all calories are processed the same way. Your body spends energy just digesting food, a phenomenon called the thermic effect of food. Protein costs the most to digest, burning 15 to 30% of the protein calories you eat just through the digestion process. Carbohydrates burn 5 to 10%, and fats burn only 0 to 3%.
This doesn’t mean you should eat nothing but protein, but it does explain why higher-protein diets tend to support weight loss beyond what the raw calorie numbers suggest. If you eat 200 calories of chicken breast, your body may spend 30 to 60 of those calories just processing it. Eat 200 calories of butter and you’ll net nearly all of them. Shifting your meals to include more protein at each sitting can effectively widen your calorie deficit without eating any less food by volume.
How Age Affects Your Number
Metabolism doesn’t fall off a cliff at any particular birthday, but it does decline slowly over time. Research published through Harvard Health found that total energy expenditure drops by about 0.7% per year in adulthood. By age 90, total daily calorie burn sits roughly 26% below that of middle-aged adults. The decline is gradual enough that you won’t notice it year to year, but over a decade or two, it adds up to a meaningful difference.
If you’re in your 50s using a calorie target you calculated in your 30s, you could be eating several hundred calories above your actual maintenance level without realizing it. Recalculating with your current age plugged into the formula is one of the simplest corrections you can make.
Putting Your Number Into Practice
Here’s a step-by-step way to find your personal calorie target for weight loss:
- Step 1: Use the Mifflin-St Jeor equation with your current weight, height, and age to get your resting metabolic rate.
- Step 2: Multiply by the activity factor that honestly matches your lifestyle. Most people with desk jobs who exercise a few times a week fall in the 1.375 to 1.55 range.
- Step 3: Subtract 500 calories for a goal of about one pound per week, or 750 for roughly 1.5 pounds per week.
- Step 4: Check that your result doesn’t drop below roughly 1,200 calories for women or 1,500 for men. Below these floors, it becomes difficult to meet basic nutritional needs.
- Step 5: Recalculate every 10 to 15 pounds lost.
The number you land on is an estimate, not a precision measurement. Even the best formulas can be off by 10% in either direction for any given person. Use your target as a starting point, follow it consistently for two to three weeks, and then adjust based on what the scale and your energy levels are telling you. If you’re losing faster than two pounds per week and feeling drained, eat a bit more. If the scale hasn’t moved after three weeks of honest tracking, trim another 100 to 200 calories or add more activity. The formula gets you in the right neighborhood. Your real-world results tell you exactly which house to walk into.