BMR for Women Age 60-64 at 100 kg — Mifflin-St Jeor

Basal metabolic rate (BMR) is the energy your body uses at complete rest — to keep your heart beating, your lungs breathing, your body warm and your cells maintained — before any movement, digestion or exercise is counted. For a 60 to 64-year-old woman weighing 100 kg (220 lb), the Mifflin-St Jeor equation gives a BMR of 1,560 kcal/day, worked step by step below using a height of 165 cm. That figure is an estimate built from a published formula, not a personal prescription.

BMR is the foundation of every calorie target. Total daily energy expenditure (TDEE) is BMR multiplied by an activity factor, and cutting, maintenance and bulking targets are all set relative to TDEE. Getting BMR right therefore matters more than it looks: a 200 kcal error in BMR becomes a 200–380 kcal error in TDEE once the activity multiplier is applied. This page shows the calculation in full so you can check it, and shows how the same person's BMR changes with weight and age, and how it converts into daily calorie needs at each activity level.

In the early sixties, resting metabolism reflects a lifetime of muscle history. The Mifflin-St Jeor age term puts BMR about 205 kcal a day below its age-21 value at the same weight and height, and the spread between individuals is now wide: someone who has strength-trained for decades can have a BMR far above the figure below, while someone who has been inactive can be far below it. Sarcopenia — age-related muscle loss — is the main driver, and it is also the main thing you can still influence. Muscle responds to resistance training at every age, and the muscle you keep is the metabolism you keep.

Calculate your own BMR

Your weight, height and age are almost certainly different from the example here, so run your own numbers with the BMR calculator. It uses the same Mifflin-St Jeor equation shown on this page. To turn BMR into a daily calorie target, use the TDEE calculator, which applies the activity multipliers.

Related pages and tools:

The formula: Mifflin-St Jeor (1990)

The Mifflin-St Jeor equation is the most widely validated formula for estimating resting energy expenditure in adults. It was published by Mifflin et al. in the American Journal of Clinical Nutrition in 1990 (Mifflin MD et al., Am J Clin Nutr 1990;51(2):241–247), and it is the equation most calculators and many clinical settings use as a starting point. For women it is:

BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161

For men the final term is +5 instead of − 161. Working through the example for a 60 to 64-year-old woman at 100 kg and 165 cm:

  • 10 × 100 kg = 1,000 kcal
  • 6.25 × 165 cm = 1,031 kcal
  • 5 × 62 years = 310 kcal
  • Constant: − 161 kcal

So BMR = 1,000 + 1,031 − 310 − 161 = 1,560 kcal/day. Every term has a meaning: weight contributes the most because a larger body costs more energy to maintain; height adds a smaller amount; age subtracts, because resting metabolism declines slowly with age; and the sex constant reflects average differences in body composition between men and women at the same weight and height.

How BMR changes with weight

At the same age (62 years) and height (165 cm), BMR rises by exactly 10 kcal a day for every extra kilogram of body weight, because the weight term is 10 × weight:

Body weight BMR
50 kg
60 kg 1,160.25 kcal/day
70 kg 1,260.25 kcal/day
80 kg 1,360.25 kcal/day
90 kg 1,460.25 kcal/day
100 kg 1,560.25 kcal/day

That 10-kcal-per-kilogram slope is also why BMR falls as you lose weight. A woman who drops 10 kg lowers BMR by about 100 kcal a day, and TDEE falls by 120–190 kcal a day depending on activity level. Calorie targets therefore need recalculating every 5 kg or so of weight change — a target set at your starting weight quietly becomes a smaller deficit, or even a surplus, as the weight comes off.

At 100 kg (220 lb) this is the heaviest weight in the BMR tables, and BMR is at its highest for this age band: 1,560 kcal a day at rest, and 1,872 kcal on a sedentary day. A 500 kcal deficit still leaves 1,372 kcal, well above the 1,200 kcal floor, so there is no reason to go anywhere near very-low-calorie intakes. The BMI at this height and weight is 36.7, in the obese range. A sustainable rate of loss is 0.5–1% of body weight a week — 0.5–1.0 kg a week at this weight — and strength training matters more here than anywhere, because preserving muscle is what keeps BMR from falling as the weight comes off.

How BMR changes with age

Holding weight (100 kg) and height (165 cm) fixed, the age term alone lowers BMR by 5 kcal a day for every year. The table below shows the same woman's BMR at different ages:

Age BMR
21 years
32 years 1,710.25 kcal/day
42 years 1,660.25 kcal/day
52 years 1,610.25 kcal/day
62 years 1,560.25 kcal/day
68 years 1,530.25 kcal/day

The gap between 21 and 68 is 235.0 kcal a day — real, but smaller than most people expect. What makes the difference larger in practice is that muscle mass and daily activity usually fall at the same time as age rises, and the equation cannot see either of those. That is why two people of the same sex, age, height and weight can have quite different resting metabolisms, and why the training and activity advice on this page matters as much as the number itself.

From BMR to daily calories: TDEE

BMR is what you burn at rest. Daily life adds movement, and TDEE is BMR multiplied by an activity factor — 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active and 1.9 for extremely active. For this 60 to 64-year-old woman at 100 kg:

| Activity level | Multiplier | TDEE | |---|---| | | Sedentary | 1.2 | 1,872 kcal/day | | Lightly active | 1.375 | 2,145 kcal/day | | Moderately active | 1.55 | 2,418 kcal/day | | Very active | 1.725 | 2,691 kcal/day | | Extremely active | 1.9 | 2,964 kcal/day | |

A cutting target is usually TDEE minus about 500 kcal a day, and a bulking target is usually TDEE plus about 300 kcal a day — but never below the safety floor of 1,200 kcal a day (women) without medical supervision. For this person, a sedentary cutting target would be 1,372 kcal a day, a moderately active maintenance target would be 2,418 kcal a day, a moderately active cutting target would be 1,918 kcal a day, and a moderately active bulking target would be 2,718 kcal a day.

How to use the 1,560 kcal figure

Use BMR as the anchor, not the target. Nobody should eat at BMR for long: it is the cost of lying still all day, and daily life always adds to it. The practical use of BMR is to build a TDEE estimate honestly — pick the activity level that matches a typical week, not your best week — and then set a goal target from TDEE. If you sit most of the day and train three times a week, you are closer to lightly active than moderately active, and the higher multiplier inflates the target by well over 100 kcal a day.

Anchor on the BMR below, build the target from an honest activity level, and keep any deficit modest — about 500 kcal a day, never below 1,200 kcal a day for women or 1,500 kcal a day for men without medical supervision. At this age, weight loss without strength training is a poor bargain: a large share of what is lost can be muscle, which lowers BMR further and makes keeping the weight off harder. Two or three strength sessions a week, protein at every meal and daily walking are the core of the plan; the calorie target is secondary to them.

What BMR does not tell you

A BMR estimate is a population average, not a measurement. Individual resting metabolic rate varies by roughly ±10% around the Mifflin-St Jeor prediction because of differences in muscle mass, genetics, thyroid function and health — for this person that means a plausible range of roughly 1,404–1,716 kcal a day. The equation uses total body weight, so it is less accurate for very muscular people (it underestimates, because muscle burns more at rest than fat) and for people with a high body-fat percentage (it overestimates). The only way to measure BMR directly is indirect calorimetry in a laboratory, which is rarely available outside research or clinical settings.

This estimate has an error band of roughly ±10% and is less precise for older adults than for younger ones, because body composition varies so much at this age. The equation uses total weight and cannot tell muscle from fat, so it underestimates BMR for muscular people and overestimates it for people with a high body-fat percentage. It also cannot see thyroid function, medication, medical conditions or sleep. Direct measurement needs indirect calorimetry in a laboratory. If you have a medical condition or take medication that affects weight, discuss targets with a healthcare professional.

The equation also cannot tell you anything about body composition, fitness or health on its own. A high BMR can belong to a muscular athlete or to a larger person with a high body-fat percentage; a low BMR can belong to a small, healthy person or to someone whose metabolism has adapted downward after a long period of very low intake. Pair BMR with other measures — waist circumference, body-fat estimates, strength, blood markers — before drawing conclusions about health. And never use BMR as an eating target: eating at or below BMR for an extended period without medical supervision risks nutrient deficiency, muscle loss and hormonal disruption.

Frequently asked questions

What is the BMR of a 60 to 64-year-old woman weighing 100 kg?

Using the Mifflin-St Jeor equation with a height of 165 cm and age 62 years, BMR is 1,560 kcal/day: 10 × 100 + 6.25 × 165 − 5 × 62 − 161 = 1,560. Your own BMR will differ if your height or exact age differ; use the BMR calculator with your own measurements.

Is Mifflin-St Jeor the most accurate BMR formula?

For most adults it is the best-validated predictive equation available, which is why it is the standard choice for calculators and clinical use. It still carries an error of roughly ±10% for an individual, because it cannot see your muscle mass — for this person that means a plausible range of about 1,404–1,716 kcal a day. Formulas that use body-fat percentage, such as Katch-McArdle, can do better for very muscular or very lean people — but only if the body-fat figure fed into them is accurate.

Can I still raise my BMR at 60-plus?

Yes — by building or keeping muscle. Resistance training increases muscle mass at any age, and muscle costs more energy at rest than fat, so BMR rises as muscle is regained. The effect is modest in absolute terms — tens of calories a day, not hundreds — but it compounds with the activity of training itself and with better balance, strength and independence. No food or supplement raises BMR by a meaningful amount on its own.

Should I eat at my BMR to lose weight?

No. BMR is the energy cost of lying still all day; eating at BMR while living a normal active life creates a deficit equal to everything you do beyond lying still, which is usually far too large and unsustainable. Set the target from TDEE instead — for this person, a moderately active cutting target is about 1,918 kcal a day — and never go below 1,200 kcal a day (women) without medical supervision.

How often should I recalculate my BMR?

Recalculate whenever your weight changes by about 5 kg, when your activity level changes for more than a few weeks, or at least once a year as you age. A target based on an old weight gradually stops working: as weight falls, BMR and TDEE fall with it — 10 kcal of BMR per kilogram — so a deficit set months ago shrinks over time. At 100 kg, each 5 kg of weight change moves BMR by 50 kcal a day.

I am not very hungry — should I eat less anyway?

Appetite often falls with age, and under-eating is a real risk in the sixties: too little food means too little protein, which accelerates muscle loss. If your appetite is low, prioritise protein at each meal and talk to a clinician before cutting calories further. Weight loss at this age should always be paired with strength training and adequate protein, and never taken below the safety floors without medical supervision.

Estimates only, not medical advice. Minimum safe intakes: 1,200 kcal/day women, 1,500 kcal/day men — consult a healthcare professional before a very-low-calorie diet.