Most women need to eat roughly 1,400 to 1,800 calories per day to lose weight at a steady pace, though your specific number depends on your age, height, weight, and how active you are. The basic principle is straightforward: you need to consume fewer calories than your body burns. A deficit of about 500 calories per day translates to roughly one pound of weight loss per week, which falls within the 1 to 2 pounds per week the CDC recommends for lasting results.
That range is a starting point, not a prescription. Your actual number could be higher or lower. Here’s how to find it.
How Your Body Burns Calories
Your body uses energy in three main ways. The biggest chunk, roughly 60 to 70 percent, goes to keeping you alive: breathing, circulating blood, repairing cells, maintaining body temperature. This is your basal metabolic rate (BMR). Physical activity accounts for another 15 to 30 percent, depending on how much you move. The remaining portion goes toward digesting food, a process that burns more energy when you eat protein and carbohydrates compared to fat.
When you add all three together, you get your total daily energy expenditure, or TDEE. That’s the number of calories your body burns in a full day. To lose weight, you eat below that number.
Calculating Your Personal Calorie Target
The most widely used formula for estimating BMR in women is the Mifflin-St Jeor equation:
BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
To convert your weight to kilograms, divide your weight in pounds by 2.2. For height, multiply inches by 2.54 to get centimeters.
Once you have your BMR, multiply it by an activity factor to estimate your total daily burn:
- 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
- Active (hard exercise 6 to 7 days per week): BMR × 1.725
- Very active (intense daily training or physical job): BMR × 1.9
Subtract 500 from that result and you have a reasonable daily calorie target for losing about one pound per week. Subtract 750 to 1,000 for faster loss closer to two pounds per week, though most women shouldn’t dip below 1,200 calories per day without medical supervision.
A Quick Example
A 35-year-old woman who weighs 170 pounds (77 kg), stands 5’5″ (165 cm), and exercises a few times a week would calculate her BMR as: (10 × 77) + (6.25 × 165) − (5 × 35) − 161 = 770 + 1,031 − 175 − 161 = 1,465 calories. Multiplied by 1.375 for light activity, her estimated daily burn is about 2,014 calories. Eating around 1,500 calories per day would create the 500-calorie deficit needed for steady weight loss.
Why the Number Changes With Age
Metabolism genuinely slows as you get older, and the shift isn’t just gradual. Research comparing sedentary premenopausal and postmenopausal women found that resting metabolic rate was approximately 10 percent lower after menopause. For a woman burning 1,400 calories at rest, that’s a drop of about 140 calories per day, enough to cause slow weight gain over time if eating habits stay the same.
This decline is partly driven by losing muscle mass, which burns more calories at rest than fat does. Women who maintained regular exercise in the same study showed a smaller decline, which is why strength training becomes increasingly important for weight management in your 40s and beyond. The calorie target you calculated at 30 will likely need to come down by your late 40s or 50s, even if your activity level hasn’t changed.
PCOS and Other Metabolic Factors
If you have polycystic ovary syndrome (PCOS), you might assume your metabolism works differently enough that standard calorie calculators won’t apply. The research tells a more reassuring story. A study measuring actual energy expenditure in women with PCOS found that the Mifflin-St Jeor equation came within 4 percent of their real calorie burn. Factors like elevated insulin levels and higher androgen levels did not significantly alter total energy expenditure once body composition was accounted for.
In practical terms, this means the formula above works for women with PCOS too. The challenge with PCOS tends to be more about hunger signals, cravings, and insulin resistance making it harder to stick to a deficit rather than needing a dramatically different calorie target.
Why Most Women Overestimate Activity Level
The single biggest source of error in calorie calculations is the activity multiplier. Most people select “moderately active” when “lightly active” or even “sedentary” is more accurate. If you work at a desk and exercise three or four times a week for 30 to 45 minutes, “lightly active” is the honest choice. “Moderately active” better describes someone who’s on their feet most of the day and also exercises regularly.
Choosing the wrong activity level can inflate your calorie target by 200 to 300 calories. If weight loss stalls, this is the first thing to revisit. Start with a lower activity estimate and adjust upward if you’re losing faster than expected or feeling consistently drained.
Setting a Realistic Deficit
A 500-calorie daily deficit is the most commonly recommended starting point because it produces visible results (roughly a pound per week) without making you miserable. Larger deficits speed things up on paper but tend to backfire in practice. They increase hunger, reduce energy for workouts, and make the plan harder to sustain.
Where you create that deficit matters too. Cutting 500 calories entirely through eating less is one approach, but combining a smaller food reduction (300 calories) with more activity (200 calories burned through exercise) tends to be easier to maintain and better for preserving muscle. Protein helps here as well. Your body burns more energy digesting protein than it does processing fat, so meals built around protein and complex carbohydrates give you a slight metabolic edge compared to high-fat meals at the same calorie count.
Calorie Ranges by Age and Size
These are general estimates for weight loss in women eating at a 500-calorie deficit, assuming light to moderate activity:
- Women in their 20s, 140 to 160 lbs: roughly 1,400 to 1,600 calories per day
- Women in their 30s, 160 to 180 lbs: roughly 1,400 to 1,550 calories per day
- Women in their 40s, 160 to 180 lbs: roughly 1,350 to 1,500 calories per day
- Women 50 and older, 150 to 170 lbs: roughly 1,250 to 1,400 calories per day
These numbers shift significantly with height and muscle mass. A 5’9″ woman will need more calories than a 5’2″ woman at the same weight because she has more lean tissue. Use the formula above for a personalized number rather than relying on these ranges alone.
Adjusting as You Lose Weight
Your calorie needs drop as you get smaller. A body that weighs 150 pounds simply requires less energy to function than one that weighs 180 pounds. This is why weight loss often stalls after a few months even when you’re eating the same amount. It’s not your metabolism “breaking.” It’s your deficit shrinking because your body now burns fewer calories at its new size.
Recalculate your target every 10 to 15 pounds lost. If you started at 1,600 calories, you may need to drop to 1,450 or increase your activity to maintain the same rate of loss. Expect the pace to slow as you get closer to your goal. Losing half a pound per week in the later stages is normal and sustainable.