Most women need to eat between 1,400 and 2,000 calories per day to lose weight, depending on age, height, current weight, and how active they are. That range is broad because no single number works for everyone. The real answer requires a quick bit of math based on your body and your daily life, and the process is simpler than it sounds.
How Your Body Burns Calories
Your body uses energy in two main ways. The first is your basal metabolic rate (BMR), the calories your body burns just to stay alive: breathing, circulating blood, maintaining body temperature. For most women, this falls somewhere between 1,200 and 1,600 calories per day. The second layer is everything you do on top of that, from walking to your car to a full gym session.
Together, these make up your total daily energy expenditure, or TDEE. To lose weight, you need to eat fewer calories than your TDEE. That gap between what you eat and what you burn is called a calorie deficit.
How to Estimate Your Personal Number
The most widely used formula for estimating BMR in women is the Mifflin-St Jeor equation: (10 × your weight in kilograms) + (6.25 × your height in centimeters) − (5 × your age in years) − 161. You can convert your weight to kilograms by dividing pounds by 2.2, and your height to centimeters by multiplying inches by 2.54.
As a quick example, a 35-year-old woman who is 5’5″ and weighs 160 pounds would calculate: (10 × 72.7) + (6.25 × 165) − (5 × 35) − 161, which comes to roughly 1,400 calories per day at rest.
Once you have your BMR, multiply it by an activity factor to get your TDEE:
- Sedentary (desk job, no planned exercise): BMR × 1.2
- Lightly active (light exercise 1 to 3 days per week): BMR × 1.375
- Moderately active (exercise 3 to 5 days per week): BMR × 1.55
- Very active (hard exercise 6 to 7 days per week): BMR × 1.725
For that same 35-year-old woman with a sedentary lifestyle, her TDEE would be about 1,680 calories. If she’s moderately active, it jumps to roughly 2,170. To lose weight, she’d subtract 500 calories from her TDEE, putting her daily target at around 1,180 (sedentary) or 1,670 (moderately active).
USDA Calorie Estimates by Age
If you don’t want to do the math, the Dietary Guidelines for Americans provide general calorie estimates for weight maintenance. These give you a starting point to subtract from:
- Ages 19 to 25: 2,000 (sedentary), 2,200 (moderately active), 2,400 (active)
- Ages 26 to 50: 1,800 (sedentary), 2,000 (moderately active), 2,200 (active)
- Ages 51 to 60: 1,600 (sedentary), 1,800 (moderately active), 2,200 (active)
- Ages 61 and older: 1,600 (sedentary), 1,800 (moderately active), 2,000 (active)
These are maintenance calories, meaning the amount to stay at your current weight. For weight loss, you’d eat below these numbers. A 40-year-old moderately active woman, for instance, maintains at roughly 2,000 calories. Cutting 500 per day would put her at 1,500 for steady weight loss.
The 500-Calorie Deficit Rule
The long-standing guideline is that cutting 500 calories per day from your TDEE leads to about one pound of weight loss per week. This is based on the old estimate that a pound of body fat stores roughly 3,500 calories. The math holds up reasonably well in the short term, though the Mayo Clinic notes that the actual rate of loss varies from person to person and tends to slow over time as your body adapts to a lower intake.
The CDC recommends losing 1 to 2 pounds per week as a sustainable pace. People who lose weight gradually are more likely to keep it off than those who drop weight quickly. A deficit of 500 calories per day targets the lower end of that range, while 1,000 per day targets the upper end. Going beyond a 1,000-calorie daily deficit is rarely necessary and often counterproductive.
The Calorie Floor: How Low Is Too Low?
There’s a practical lower limit to how few calories you should eat. Most nutrition guidelines place that floor at around 1,200 calories per day for women. Eating below this level makes it extremely difficult to get adequate vitamins, minerals, protein, and fiber. It can also trigger your body to break down muscle for energy, which lowers your metabolic rate and makes future weight loss harder.
If cutting 500 calories from your TDEE would drop you below 1,200, the smarter approach is to create part of your deficit through food and part through exercise. A woman with a TDEE of 1,600, for example, could cut 250 calories from her diet and burn an additional 250 through a 30-minute brisk walk, reaching that 500-calorie deficit without eating dangerously little.
Why Age Matters Less Than You Think
It’s common to hear that metabolism “slows down after 30,” but a large-scale study published in Science and covered by Harvard Health found something surprising: metabolic rate stays relatively stable from age 20 all the way to about 60 when adjusted for body size. The real decline begins around age 63, dropping by about 0.7% per year after that. By age 90, adjusted energy expenditure is roughly 26% below middle-age levels.
What does change in your 30s, 40s, and 50s is muscle mass, activity level, and daily habits. These shifts reduce how many calories you burn, but they aren’t the same as your metabolism fundamentally slowing. This is good news because it means exercise and strength training can directly counteract most of the change.
Menopause and Calorie Needs
Menopause does appear to affect calorie needs, though the mechanism is more about body composition than a metabolic switch. A study of postmenopausal women found that standard calorie formulas overestimated their resting metabolic rate by 150 to over 300 calories per day compared to what was actually measured. The Mifflin-St Jeor equation came closest but still overshot.
If you’re postmenopausal and using an online calculator, it’s worth knowing that your actual calorie needs may be somewhat lower than what the tool reports. Starting with the calculator’s estimate and adjusting based on two to three weeks of real-world results is a more reliable strategy than trusting any formula at face value.
Signs Your Deficit Is Working
The scale is one measure of progress, but it’s not the only one and often not the most reliable week to week. Water retention, hormonal fluctuations across the menstrual cycle, and changes in muscle mass can all mask fat loss on the scale for days or even weeks at a time.
Pay attention to how your clothes fit, especially around the waist and hips. Looser clothing often shows up before the scale moves, particularly if you’re exercising and building some muscle. Other reliable signals include better sleep quality, more consistent energy through the day without afternoon crashes, improved endurance during walks or workouts, and lower resting heart rate or blood pressure readings at checkups. These changes indicate your body is responding to the deficit even when the number on the scale is stubborn.
Putting It All Together
Here’s the straightforward process: estimate your BMR using the Mifflin-St Jeor equation, multiply by your activity level to get your TDEE, and subtract 500 calories. That’s your daily calorie target for losing about a pound a week. If your number lands below 1,200, close the gap with more movement rather than less food.
Track your intake and your weight for two to three weeks. If you’re losing 0.5 to 2 pounds per week on average, you’ve found your range. If nothing is changing, your TDEE estimate may be too high, which is common because most people overestimate how active they are and underestimate how much they eat. Drop your daily target by 100 to 200 calories and reassess. Small, consistent adjustments beat dramatic cuts every time.