What is the BMR for a 45-year-old woman?

The estimated BMR (basal metabolic rate) for a 45-year-old woman of average height and weight is 1366 kcal/day, calculated using the Mifflin-St Jeor equation.

Calorie Guide · Age 45

Calories for a 45-Year-Old Woman

Q: How many calories does a 45-year-old woman need?

A lightly active 45-year-old woman of average weight and height needs approximately 1878 kcal/day to maintain weight. Sedentary needs are around 1639 kcal, and very active around 2357 kcal.

Q: How many calories should a 45-year-old woman eat to lose weight?

A 45-year-old woman should eat approximately 1378 kcal/day to lose about 0.5 kg (1 lb) per week. This is a 500 kcal deficit from the estimated maintenance of 1878 kcal.

BMR, TDEE and exact calorie targets for weight loss, maintenance and muscle gain at age 45.

Calorie Needs at Age 45 — Average Woman

1366

BMR (at rest)

1639

Sedentary TDEE

1878
Lightly active TDEE

2117

Moderately active

1378

Weight loss target

1878

Maintenance

2178

Muscle gain target

How Many Calories Does a 45-Year-Old Woman Need?

Using the Mifflin-St Jeor equation with average US height and weight for a woman aged 45, the resting metabolic rate (BMR) is approximately 1366 kcal/day. With typical daily activity included, total calorie expenditure (TDEE) ranges from 1639 kcal (sedentary) to 2357 kcal (very active).

Age 45 note: After 40, muscle loss (sarcopenia) accelerates if untrained. Strength training 2–3×/week and higher protein intake (1 g/lb) are the most effective countermeasures.

Calorie Targets by Goal

Goal	Daily Calories	Expected Result
🔵 Aggressive weight loss	1128 kcal	~0.75 kg/week
📉 Weight loss	1378 kcal	~0.5 kg/week
✅ Maintenance	1878 kcal	Weight stable
💪 Lean bulk	2178 kcal	~0.25 kg/week
🏋️ Aggressive bulk	2378 kcal	~0.5 kg/week

Calorie Needs by Activity Level

Activity Level	Description	Daily Calories
Sedentary	Desk job, minimal movement	1639 kcal
Lightly active	1–3 workouts/week	1878 kcal
Moderately active	3–5 workouts/week	2117 kcal
Very active	Hard training 6–7 days/week	2357 kcal

How Metabolism Changes Around Age 45

Metabolic rate declines approximately 1–2% per decade after age 30, driven primarily by muscle loss (sarcopenia) rather than any inherent slowdown. At age 45, your BMR of 1366 kcal reflects your current muscle mass, height and hormonal status. The single most effective way to maintain or raise your BMR is resistance training — each kilogram of lean muscle burns roughly 13 kcal/day at rest.

Age	Estimated BMR (woman)	Change vs age 45
35	1416 kcal	+50 kcal
40	1391 kcal	+25 kcal
45	1366 kcal	—
50	1341 kcal	-25 kcal
55	1316 kcal	-50 kcal

Macronutrient Split at 1878 kcal

Macro	% of Calories	Grams/day	Calories
Protein	30%	141 g	564 kcal
Carbohydrates	40%	188 g	752 kcal
Fat	30%	63 g	567 kcal

At age 45, protein intake is especially important. Aim for at least 60–74 g/day to maintain muscle mass, whether you're in a deficit, at maintenance, or in a surplus.

Get personalized calorie targets based on your exact weight, height and activity level.

Calculate My TDEE →

Frequently Asked Questions

How many calories does a 45-year-old woman need per day?A lightly active 45-year-old woman of average size needs approximately 1878 kcal/day to maintain weight. This ranges from 1639 kcal (sedentary) to 2357 kcal (very active).

How many calories should a 45-year-old woman eat to lose weight?Aim for 1378 kcal/day — a 500 kcal deficit from the 1878 kcal maintenance estimate — to lose approximately 0.5 kg per week. Never go below 1200 kcal (women) or 1500 kcal (men) for extended periods.

Does age 45 affect how many calories you burn?Yes. Every decade after 30, BMR drops ~1–2% mainly due to muscle loss. At age 45 the estimated BMR is 1366 kcal — compare to 1441 kcal at age 30. Resistance training largely offsets this decline.

Related Age Guides

Sources

WHO CDC Mifflin-St Jeor (PubMed)