How to Calculate Daily Calories for Women Over 40: Fat Loss, Muscle Gain, and Body Recomposition
Tired of guessing how many calories you need to eat to actually see results? You’re not alone! Today, I’m breaking down the exact, science-backed steps and formulas I use with my online fitness and nutrition coaching clients to help them lose body fat, build lean muscle, and finally get the results they’ve been working so hard for.
Whether your goal is fat loss, muscle gain, or a true body recomposition, this guide will walk you through how to calculate your daily calorie needs—no more confusion or trial and error.
1. What is Resting Metabolic Rate (RMR)?
Your Resting Metabolic Rate (RMR) is the number of calories your body needs to maintain basic physiological functions—like breathing, circulation, and cell reproduction—even when you’re at rest. Think of it as your body’s baseline energy requirement before any movement or exercise.
2. The Best Formula to Calculate Your RMR (Mifflin-St Jeor)
There are a couple of ways to calculate RMR, but for everyday use, we use predictive equations based on age, sex, weight, and height.
The Mifflin-St Jeor Equation (most accurate for women):
RMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
Step-by-Step Example:
Let’s use one of my online fitness clients, Michelle, as an example.
Michelle’s Stats:
Age: 45
Weight: 170 lbs (77.1 kg)
Height: 5’6” (167.6 cm)
Step 1: Convert to Metric
- Weight: 170 lbs × 0.4536 = 77.1 kg
- Height: 5’6″ = 66 in × 2.54 = 167.6 cm
Step 2: Plug into the Equation
- RMR = (10 × 77.1) + (6.25 × 167.6) – (5 × 45) – 161
- RMR = 771 + 1047.5 – 225 – 161
- RMR = 1,432 calories/day
This is the minimum Michelle’s body needs to function at rest.
3. Understand NEAT: Daily Movement That Matters
Beyond your RMR, your daily movement burns extra calories. These are divided into:
- NEAT (Non-Exercise Activity Thermogenesis):
Calories burned from daily, non-exercise movement—walking, housework, fidgeting, etc. - EAT (Exercise Activity Thermogenesis):
Calories burned from structured workouts—strength training, cardio, sports.
How to Estimate NEAT:
- Sedentary: 10-20% of RMR (mostly sitting, desk job)
- Lightly Active: 20-30% of RMR (some walking, light chores)
- Moderately Active: 30-40% of RMR (regular movement, active job)
- Highly Active: 40-50% of RMR (manual labor, very active lifestyle)
Michelle’s Example:
- Michelle gets at least 8,000 steps a day and is active with her kids, so I place her in the lightly active range.
- NEAT = 25% of 1,432 = ~350 calories
4. Estimate Calories Burned from Workouts (EAT)
The most accurate way to estimate exercise calories is with a fitness tracker, but here’s a solid starting point:
- Strength Training: 5 calories per minute
- Cardio: 8 calories per minute (at higher intensity)
Michelle’s Weekly Example:
- Strength: 4 × 45 minutes = 180 minutes × 5 = 900 calories/week
- Cardio: 2 × 30 minutes = 60 minutes × 8 = 480 calories/week
- Total Weekly: 1,380 calories ÷ 7 = ~197 calories/day
5. Put It All Together: Calculate Your TDEE
TDEE (Total Daily Energy Expenditure) is the total calories needed to maintain your current weight:
TDEE = RMR + NEAT + EAT
Michelle’s Example:
- RMR: 1,432
- NEAT: 350
- EAT: 197
- TDEE = 1,979 calories/day
Many women are surprised their maintenance calories are this high!
6. Adjust Your Calories for Fat Loss, Muscle Gain, or Recomp
Now it’s time to align your calorie intake with your goal:
Calculate Daily Calories For Fat Loss:
- Subtract 400–500 calories from your TDEE
- Never go below 1,200–1,300 calories/day (protect your metabolism and muscle!)
Calculate Daily Calories For Muscle Gain:
- Add ~200 calories to your TDEE
- Reassess after 2–3 weeks
For Body Recomposition (lose fat, gain muscle):
- Subtract 200–300 calories from your TDEE
- Keep protein at at least 30% of total calories
7. Ready to Get Real Results?
You now know how to calculate your own RMR, estimate your daily movement and exercise calories, and adjust your intake based on your personal goal—no more guessing, just science-backed, real-world results.
Grab your pen or phone, do your numbers, and take the guesswork out of your nutrition! If you need help customizing these calculations or want a plan built for your unique body, reach out—I’d love to help you get started.
Want An Expert To Help You Reach Your Goals?
FAQ: Daily Calorie Needs for Women Over 40
1. How many calories should a woman over 40 eat per day to lose weight?
Most women over 40 need between 1,300 and 1,700 calories per day for fat loss, depending on their size, activity level, and metabolism. Never go below 1,200–1,300 calories per day without medical supervision. Calculate your Total Daily Energy Expenditure (TDEE) and subtract 400–500 calories for safe, sustainable fat loss.
2. Why do calorie needs change after 40?
Calorie needs decrease as we age because metabolism slows, muscle mass tends to decline, and hormone changes affect how we burn and store energy. That’s why it’s important to recalculate your needs regularly, especially after age 40.
3. What is the best calorie calculator for women over 40?
The Mifflin-St Jeor Equation is considered the most accurate calorie calculator for women over 40 because it accounts for age, weight, height, and sex. Use the step-by-step example in this article to find your personal baseline.
4. Should I eat back the calories I burn from exercise?
No. Your TDEE calculation already includes exercise calories, so you do not need to “eat back” calories from workouts. Instead, set your daily intake based on your TDEE and your specific goal (fat loss, muscle gain, or recomposition).
5. What is the minimum number of calories a woman should eat for fat loss after 40?
Women should not go below 1,200–1,300 calories per day, even when trying to lose weight. Extremely low-calorie diets can slow metabolism, cause muscle loss, and negatively impact hormones and overall health.
6. How important is protein when trying to lose fat or build muscle over 40?
Protein is crucial for protecting muscle mass, supporting metabolism, and improving body composition—especially as you age. Aim for at least 30% of your total daily calories from protein, or about 0.8–1.0 grams per pound of goal body weight.
7. Can I build muscle and lose fat at the same time after 40?
Yes, with the right calorie intake and a high-protein diet, women over 40 can achieve body recomposition—gaining muscle while losing fat. This typically involves a slight calorie deficit, strength training, and prioritizing protein.
8. How often should I recalculate my daily calorie needs?
Recalculate your calorie needs whenever your weight, activity level, or goals change significantly—typically every 8–12 weeks, or after losing more than 10 pounds.
9. Do menopause or perimenopause affect how many calories I need?
Yes. Hormonal changes during perimenopause and menopause can slow metabolism and impact how your body uses calories. Adjusting your calorie intake, focusing on protein, and staying active become even more important.
10. What if I feel tired or hungry all the time while dieting?
Feeling constantly fatigued or hungry can mean your calorie deficit is too aggressive. Try increasing your calories slightly, prioritize nutrient-dense foods, and make sure you’re getting enough protein and fiber.
Scientific Appendix
Hall, Kevin D., et al. “Energy Balance and Its Components: Implications for Body Weight Regulation.” The American Journal of Clinical Nutrition, vol. 95, no. 4, 2012, pp. 989–994.
doi:10.3945/ajcn.112.036350.
Mifflin, Mark D., et al. “A New Predictive Equation for Resting Energy Expenditure in Healthy Individuals.” The American Journal of Clinical Nutrition, vol. 51, no. 2, 1990, pp. 241–247.
doi:10.1093/ajcn/51.2.241.
Pasiakos, Stefan M., et al. “Protein Requirements and Recommendations for Older Adults: Impact of Aging on Muscle Mass, Strength, and Function.” Nutrients, vol. 13, no. 7, 2021, article 2212. doi:10.3390/nu13072212.
Poehlman, Eric T., et al. “Menopause, Energy Expenditure, and Body Composition.” Acta Obstetricia et Gynecologica Scandinavica, vol. 78, no. 7, 1999, pp. 533–537.
doi:10.1080/j.1600-0412.1999.780703.x.