BMR for Men Age 65+ at 70 kg — Mifflin-St Jeor

BMR — basal metabolic rate — is what the body burns doing nothing at all: breathing, circulating blood, maintaining temperature, repairing cells. For a 65+-year-old man at 70 kg (154 lb) and 178 cm, the Mifflin-St Jeor equation gives 1,478 kcal/day. This page works the calculation out in full, shows how the figure moves with weight, and turns it into daily calorie targets at every activity level.

The value of a worked example is that it can be checked. Too many calculators show a single number with no working, so there is no way to tell whether the inputs were right. Below, the Mifflin-St Jeor formula is written out, every term is calculated for this exact man — age 68, weight 70 kg, height 178 cm — and the result is then carried through into BMR at other weights and TDEE at all five activity levels, so the whole chain from inputs to daily calories is visible.

After 65, the equation's age term removes 340 kcal a day or more, and muscle loss — sarcopenia — becomes the dominant story. Resting metabolism falls not just because of age but because the most metabolically active tissue is shrinking. At this age, BMR is best used alongside a protein target and a strength routine: roughly 1.6 g of protein per kilogram a day, spread across meals, plus resistance training two or three times a week, does more to protect health and independence than chasing the lowest possible calorie number. Any weight-loss plan at this age should be discussed with a clinician first.

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 men it is:

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

For women the final term is −161 instead of +5. Working through the example for a 65+-year-old man at 70 kg and 178 cm (age 68 years, the middle of the band):

  • 10 × 70 kg = 700 kcal
  • 6.25 × 178 cm = 1,112.5 kcal
  • 5 × 68 years = 340 kcal
  • Constant: +5 kcal

So BMR = 700 + 1,112.5 − 340 + 5 = 1,478 kcal/day (rounded to the nearest whole calorie). 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 (68 years) and height (178 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 1,278 kcal/day
60 kg 1,378 kcal/day
70 kg 1,478 kcal/day
80 kg 1,578 kcal/day
90 kg 1,678 kcal/day
100 kg 1,778 kcal/day

That 10-kcal-per-kilogram slope is also why BMR falls as you lose weight. A man 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.

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 65+-year-old man at 70 kg:

Activity level Multiplier TDEE
Sedentary 1.2 1,774 kcal/day
Lightly Active 1.375 2,032 kcal/day
Moderately Active 1.55 2,291 kcal/day
Very Active 1.725 2,550 kcal/day
Extremely Active 1.9 2,808 kcal/day

A cutting target is usually TDEE minus about 500 kcal a day, and a bulking target is usually TDEE plus about 300–350 kcal a day — but never below the safety floor of 1,500 kcal a day (men) without medical supervision. For this person, a moderately active cutting target would be about 1,791 kcal a day, maintenance about 2,291 kcal a day, and a bulking target about 2,591 kcal a day. Note that a sedentary cutting target would be 1,274 kcal on the maths alone, so the 1,500 kcal safety floor applies instead — never eat below 1,500 kcal a day without medical supervision.

How to use the 1,478 kcal figure

Treat the 1,478 kcal figure as the floor of your energy budget, not the budget itself. Every step, every workout and every hour on your feet sits on top of it, which is why the TDEE table above spans from 1,774 kcal a day (sedentary) to 2,808 kcal a day (extremely active) for the same man. Choosing the wrong row is the single most common calorie mistake: people pick the activity level they aspire to, not the one they live, and then wonder why the target does not work.

Revisit the number whenever weight moves by about 5 kg. At 70 kg, losing 10 kg cuts BMR by 100 kcal a day and TDEE by 120–190 kcal a day, so a deficit that worked at the start quietly shrinks as weight falls. A one-minute recalculation every few months keeps the target matched to the body it is meant to serve.

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. 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.

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 65+-year-old man weighing 70 kg?

Using the Mifflin-St Jeor equation with a height of 178 cm and age 68 years, BMR is 1,478 kcal/day: 10 × 70 + 6.25 × 178 − 5 × 68 + 5 = 1,478. 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. 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.

Does BMR fall with age?

Yes. The equation subtracts 5 kcal a day per year of age, so BMR falls by about 50 kcal a decade at the same weight and height. In practice the decline is often larger because muscle mass and daily activity tend to fall with age too. Resistance training is the most effective countermeasure, because it preserves the muscle that keeps resting metabolism up.

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 man, about 2,291 kcal a day at moderate activity — and never go below 1,500 kcal a day (men) 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, so a deficit set months ago shrinks over time.

What is my TDEE if I am moderately active at 70 kg?

Multiply BMR by 1.55: 1,478 × 1.55 = 2,291 kcal/day. That is the maintenance figure — the intake that, on average, holds weight steady at this activity level. A cutting target from there is about 1,791 kcal a day and a bulking target about 2,591 kcal a day, always staying above the 1,500 kcal safety floor.

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.