Most people need to eat 500 to 750 fewer calories than they burn each day to lose weight at a steady, sustainable pace of one to two pounds per week. But “how many calories” isn’t a single number that works for everyone. It depends on your height, weight, age, sex, and how active you are. The good news is that calculating a personalized target takes only a few steps.
How a Calorie Deficit Actually Works
Your body is always burning a mix of fuel sources, primarily carbohydrates and fat. When you consistently eat less energy than you use, your body pulls from its stored fat to make up the difference. Interestingly, your fat cells release fatty acids into your bloodstream at roughly twice the rate your body can burn them at rest. Most of those fatty acids cycle back into storage. A calorie deficit tips that balance so more fat gets burned and less gets stored, which is how you lose body fat over time.
A pound of body fat stores roughly 3,500 calories of energy. That’s why a daily deficit of 500 calories translates to about one pound lost per week, and 750 calories per day gets you closer to one and a half pounds. The CDC notes that people who lose at this gradual pace of one to two pounds weekly are more likely to keep it off than those who drop weight faster.
Step 1: Estimate Your Resting Metabolic Rate
Your resting metabolic rate (RMR) is the number of calories your body burns just to keep you alive: breathing, circulating blood, maintaining body temperature. The most widely recommended formula for estimating it is the Mifflin-St Jeor equation, endorsed by the Academy of Nutrition and Dietetics.
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
To convert your weight, divide pounds by 2.2. To convert your height, multiply inches by 2.54. For example, a 35-year-old woman who weighs 170 pounds (77 kg) and stands 5’6″ (168 cm) would calculate: (10 × 77) + (6.25 × 168) − (5 × 35) − 161 = 1,459 calories per day at rest.
Step 2: Factor In Your Activity Level
You don’t just lie in bed all day, so your actual calorie burn is higher than your resting rate. Multiply your RMR by an activity factor to get your total daily energy expenditure (TDEE):
- Sedentary (desk job, little exercise): multiply by 1.2
- Lightly active (light exercise 1 to 3 days per week): multiply by 1.375
- Moderately active (moderate exercise 3 to 5 days per week): multiply by 1.55
- Very active (hard exercise 6 to 7 days per week): multiply by 1.725
- Extremely active (intense training or physical labor job): multiply by 1.9
Using the same example, if that 35-year-old woman exercises moderately three to five days a week, her TDEE would be about 1,459 × 1.55 = 2,261 calories. That’s roughly what she burns in a full day. To lose about one pound per week, she’d aim for around 1,761 calories daily (2,261 minus 500).
Most people overestimate their activity level. If you work at a desk and go to the gym three times a week for 30 to 45 minutes, “lightly active” is probably more accurate than “moderately active.” Being honest here makes a bigger difference than perfecting the math.
Calorie Floors You Shouldn’t Go Below
Harvard Health Publishing recommends that women eat no fewer than 1,200 calories per day and men no fewer than 1,500 per day unless supervised by a health professional. Going lower than these thresholds makes it very difficult to get the vitamins, minerals, and protein your body needs. If your math produces a target below those numbers, a smaller deficit with added exercise is a safer path.
Why Tracking Feels Harder Than It Should
Even careful trackers tend to undercount what they eat. Research published in The American Journal of Clinical Nutrition found that people underreport their calorie intake by an average of 11 to 25 percent. That means someone who logs 1,800 calories might actually be eating 2,000 to 2,250. The biggest culprits are cooking oils, sauces, drinks, and “just a bite” portions that never get recorded.
This doesn’t mean tracking is pointless. It means you should expect some learning curve. Weighing food on a kitchen scale for even a week or two dramatically improves your accuracy and teaches you what realistic portions look like. After that initial calibration, most people can estimate well enough without weighing everything forever.
Eating More Food on Fewer Calories
A calorie deficit doesn’t have to mean feeling hungry all the time. Research from The American Journal of Clinical Nutrition shows that people tend to eat a fairly consistent weight of food each day. If you fill that volume with foods that are lower in calorie density, meaning fewer calories per gram, you eat the same physical amount of food while taking in less energy.
Foods with high water and fiber content are naturally low in calorie density: vegetables, fruits, broth-based soups, cooked whole grains, and legumes. A large bowl of vegetable soup might contain 150 calories, while the same weight in crackers could top 500. You can figure out a food’s calorie density yourself by dividing the calories on the label by the serving size in grams. Foods below about 1.5 calories per gram are considered low density and can be eaten in generous portions.
Protein Keeps You Full and Protects Muscle
When you lose weight, some of that loss comes from muscle unless you actively work to prevent it. The two most effective tools for preserving muscle are resistance training and eating enough protein. For people who exercise regularly, research recommends 1.6 to 2.4 grams of protein per kilogram of body weight each day during a calorie deficit. For our 170-pound example, that works out to roughly 123 to 185 grams of protein daily.
If you don’t exercise intensely, you can aim for the lower end of that range. Protein also happens to be the most satiating nutrient, meaning it keeps you feeling full longer per calorie than carbohydrates or fat. Prioritizing protein at each meal, things like eggs, chicken, fish, Greek yogurt, beans, and tofu, makes the deficit easier to maintain without constant hunger.
Adjusting Over Time
Your calorie target isn’t permanent. As you lose weight, your body gets smaller and burns fewer calories both at rest and during activity. Someone who loses 20 pounds will have a noticeably lower TDEE than when they started. If weight loss stalls for two to three weeks (not just a few days, since water weight fluctuates naturally), recalculate your RMR and TDEE with your current weight. You’ll likely need to trim another 100 to 200 calories or add more movement.
Plateaus can also signal that your tracking has drifted. Before cutting calories further, spend a week measuring portions more carefully. That alone often reveals the gap. The 2025 Dietary Guidelines for Americans reinforce focusing on whole, nutritious foods and limiting highly processed foods, added sugars, and refined carbohydrates, which is practical advice that naturally helps keep calories in check without obsessive counting.