What TDEE means for women specifically
TDEE represents the total number of calories your body burns in a 24-hour period, encompassing everything from keeping your heart beating and brain functioning at rest (your Basal Metabolic Rate, or BMR), to the energy cost of digesting food (the Thermic Effect of Food), to all physical movement including structured exercise and incidental activity like walking to the kitchen or fidgeting.
For women, TDEE has some unique characteristics. On average, women have lower TDEEs than men of the same age, height, and weight, primarily because women carry a higher proportion of body fat relative to muscle mass. Fat tissue burns far fewer calories at rest than muscle tissue. A woman and man both weighing 75 kg may have TDEEs differing by 200–400 kcal/day purely due to body composition differences.
Additionally, hormonal cycles across the month, decade, and lifetime cause TDEE to shift in ways that are not captured by a single calculation. Understanding this is not a reason to distrust the numbers — it is a reason to treat them as a calibration starting point that you refine over a few weeks of real-world data.
The Mifflin-St Jeor formula: a worked example
The Mifflin-St Jeor equation is the most widely validated BMR formula for women. Multiple studies have found it to be more accurate than the older Harris-Benedict equation for modern populations. The formula is:
BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
Let's work through a complete example. Meet Sarah: a 38-year-old woman, 163 cm tall, weighing 68 kg, who works a desk job and does gym sessions 3 times per week.
Sarah's BMR calculation:
(10 × 68) + (6.25 × 163) − (5 × 38) − 161
= 680 + 1,018.75 − 190 − 161
= 1,347 kcal/day (BMR)
This BMR represents the calories Sarah burns if she did nothing but lie still for 24 hours. To get her TDEE, we multiply by an activity factor.
How activity level affects TDEE
The activity multiplier converts BMR into a full-day energy estimate. Here are the standard activity levels and their multipliers:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | × 1.2 | Desk job, little to no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days/week |
| Moderately active | × 1.55 | Moderate exercise 3–5 days/week |
| Very active | × 1.725 | Hard exercise 6–7 days/week |
| Extra active | × 1.9 | Very hard daily exercise or physical job |
Returning to Sarah: with moderate exercise 3 days per week (light-to-moderate activity, multiplier 1.375), her TDEE is approximately:
TDEE = 1,347 × 1.375 = 1,852 kcal/day
This is the number of calories Sarah needs to maintain her current weight.
One important caveat: most people — both men and women — overestimate their activity level. If you work a desk job and do three 45-minute gym sessions per week but are otherwise sedentary, the lightly active multiplier (1.375) is likely more accurate than moderately active (1.55). Starting conservatively and adjusting based on real weight trends over 2–3 weeks is the most reliable approach.
How hormones and the menstrual cycle affect TDEE
The standard TDEE formula gives you a single daily number, but in reality, a woman's calorie burn varies across the menstrual cycle. Research shows that TDEE is lowest in the early follicular phase (the days just after your period ends) and peaks in the late luteal phase (the week before your next period), with a difference of approximately 100–300 kcal/day.
The main driver of this increase is progesterone. As progesterone rises in the second half of the cycle, it elevates body temperature slightly (similar to a very mild fever), which increases the metabolic rate. Simultaneously, progesterone increases appetite — the body is signalling that more energy is needed.
Practically, this means that your calculated TDEE is best understood as a 28-day average. You may find you need slightly fewer calories in the first half of your cycle and slightly more in the second half. Rather than fighting this variation, you can align your eating to it: apply a stricter deficit in the follicular phase when hunger is lower, and eat closer to maintenance in the luteal phase when hunger is higher. The net weekly average remains the same.
TDEE during pregnancy and breastfeeding
Pregnancy significantly increases TDEE. The general guidance from health bodies is that energy needs increase by approximately 300 kcal/day during the second trimester and 450 kcal/day during the third trimester, though individual variation is substantial. The first trimester requires minimal additional calories despite what many people assume.
Breastfeeding increases calorie needs by roughly 300–500 kcal/day above pre-pregnancy TDEE. This is one of the reasons many new mothers lose weight gradually while nursing — if eating at pre-pregnancy levels, they are already in a mild deficit.
Neither pregnancy nor early postpartum is the right time to pursue aggressive weight loss. Adequate nutrition for both the mother and infant is the priority, and any weight management goals should be discussed with a healthcare provider.
TDEE during perimenopause and menopause
TDEE typically declines with age, primarily because muscle mass decreases (a process called sarcopenia) and the remaining muscle becomes slightly less metabolically active. Between age 30 and 70, women may lose 20–30% of their skeletal muscle mass if they do not actively train to preserve it.
The decline in oestrogen during perimenopause (usually beginning in the mid-40s) accelerates both muscle loss and fat accumulation, particularly around the abdomen. This means the same TDEE formula at age 50 may overestimate actual calorie needs by 5–10% compared to age 35, simply because body composition has shifted.
The best countermeasure is progressive resistance training, which builds and maintains muscle mass, keeping BMR and TDEE higher. Women in perimenopause and postmenopause who weight-train consistently have significantly higher TDEEs than age-matched sedentary peers.
How to use your TDEE for different goals
Weight loss
Eat 300–500 kcal below your TDEE. For Sarah (TDEE: 1,852 kcal), a 400 kcal deficit means a target of approximately 1,450 kcal/day. Use our Calorie Deficit Calculator to find your specific target and projected loss rate.
Maintenance
Eat at or within roughly 100 kcal of your TDEE. Weight will fluctuate day to day by 1–2 kg due to water retention, food volume, and hormonal changes — this is entirely normal and not a sign that maintenance has failed.
Muscle gain
Eat 150–250 kcal above your TDEE. Women gain muscle much more slowly than men due to lower testosterone levels, which means a large caloric surplus simply adds fat rather than extra muscle. A modest surplus of 150–250 kcal is more than sufficient to support maximal muscle gain while minimising fat accumulation.
Recalibrating your TDEE over time
No formula is perfectly accurate for every individual. The most reliable way to verify and adjust your TDEE is to track your food intake carefully for 2–3 weeks while weighing yourself daily. If your weight is stable, you have found your true TDEE. If it is drifting upward or downward, adjust by 100–150 kcal and reassess.
Also recalculate every 5–10 kg of weight change — as your weight decreases, your TDEE decreases too. This is the main reason fat loss slows over time and why adjusting targets every few weeks is essential for continued progress.