Most people will lose weight eating between 1,500 and 2,000 calories per day, but your specific number depends on your size, age, sex, and how active you are. A good starting point is to figure out how many calories your body burns in a typical day, then eat 500 fewer than that. That gap between what you eat and what you burn is called a calorie deficit, and it’s the core mechanism behind every weight loss approach.
How to Estimate Your Daily Calorie Needs
Your body burns a baseline number of calories just keeping you alive: breathing, circulating blood, maintaining body temperature. This is your basal metabolic rate, or BMR. The most widely used formula for estimating it is the Mifflin-St Jeor equation, which accounts for weight, height, age, and sex:
- Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
- Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
That gives you the calories your body needs at complete rest. To get a realistic daily number, you multiply by an activity factor: 1.2 if you’re sedentary (desk job, little exercise), 1.375 if you’re lightly active (walking a few times a week), 1.55 if you’re moderately active (exercise 3 to 5 days a week), and 1.725 or higher if you’re very active. The result is roughly how many calories you burn in a full day, sometimes called your total daily energy expenditure.
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 BMR around 1,432 calories. Multiplied by 1.375 for light activity, her daily burn comes to about 1,970 calories. To lose weight, she’d aim to eat around 1,470 to 1,500 calories per day.
How Big Your Deficit Should Be
Cutting about 500 calories per day from your maintenance level typically produces about half a pound to one pound of weight loss per week, according to the Mayo Clinic. The old rule that 3,500 calories equals one pound of fat is a rough guideline, not a precise formula. In practice, weight loss varies depending on your starting weight, sex, body composition, and how long you’ve been dieting.
A 500-calorie daily deficit is the most common recommendation because it’s aggressive enough to produce visible results within a few weeks but moderate enough that most people can sustain it. Larger deficits (750 to 1,000 calories per day) will speed things up initially, but they’re harder to stick with and more likely to cause muscle loss, fatigue, and the kind of intense hunger that leads to binge eating. For most people, slow and steady wins here.
The Floor: Don’t Go Below These Numbers
Harvard Health recommends that women eat no fewer than 1,200 calories per day and men no fewer than 1,500 calories per day unless supervised by a healthcare provider. Dropping below these thresholds makes it very difficult to get adequate vitamins, minerals, and fiber from food alone. It also increases the risk of gallstones, hair loss, and losing muscle instead of fat.
If your calculated deficit puts you below those minimums, the better strategy is to increase your activity level rather than restrict food further. Adding a 30-minute walk burns roughly 150 to 200 extra calories and widens your deficit without requiring you to eat less.
Why Weight Loss Slows Down Over Time
Almost everyone hits a plateau, and it’s not because you’re doing something wrong. When you lose weight and eat less, your body adapts. Insulin secretion decreases, thyroid hormone levels drop, and leptin (the hormone that signals fullness) falls. Your cells also become more efficient at using energy, meaning you burn fewer calories doing the same activities you did before. This process, called metabolic adaptation, is your body’s built-in resistance to weight loss.
This is why the calorie target that worked in month one may stop producing results by month three. The fix is to recalculate your needs periodically, roughly every 10 to 15 pounds lost. Your maintenance calories drop as your body gets smaller, so the deficit shrinks unless you adjust.
Protein Matters More During a Deficit
When you’re eating fewer calories than your body needs, it doesn’t just pull from fat stores. It breaks down muscle tissue too, especially if your protein intake is low. To minimize muscle loss, aim for 0.7 to 1.0 grams of protein per pound of body weight each day. For a 170-pound person, that’s roughly 120 to 170 grams of protein daily.
That number sounds high, and it is compared to what most people eat. Prioritizing protein at every meal (eggs at breakfast, chicken or legumes at lunch, fish at dinner) makes it much easier to hit that range. Protein also happens to be the most filling macronutrient, so eating more of it tends to reduce hunger naturally, which makes the deficit easier to maintain.
Making Fewer Calories Feel Like Enough Food
The biggest challenge with eating in a deficit isn’t knowing the number. It’s not feeling hungry all the time. This is where calorie density becomes a practical tool. Foods that are high in water and fiber take up a lot of space in your stomach while delivering relatively few calories, so you feel full on less.
The differences are dramatic. One cup of raisins has about 480 calories, while one cup of grapes (essentially the same fruit, just with water intact) has about 104. A small order of french fries runs around 250 calories. For the same 250 calories, you could eat 10 cups of spinach, a cup and a half of strawberries, and a small apple. A single pat of butter contains almost the same calories as two cups of raw broccoli.
This doesn’t mean you need to eat only salads. It means that building meals around vegetables, fruits, lean proteins, and whole grains, then adding smaller amounts of calorie-dense foods like oils, nuts, and cheese, lets you eat a satisfying volume of food without blowing past your target. You feel like you’re eating a full plate because you are.
Putting It All Together
Start by estimating your daily calorie burn using the formula above or an online calculator based on the Mifflin-St Jeor equation. Subtract 500 calories from that number. Check that your target doesn’t fall below 1,200 (women) or 1,500 (men). Keep protein high, build meals around low-calorie-density foods, and recalculate every couple of months as your weight changes. Track your intake for at least the first few weeks so you learn what portions actually look like, since most people significantly underestimate how much they eat. After that, many people find they can maintain a deficit by habit without logging every meal.