BMR for Men Age 25-29 at 90 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 25 to 29-year-old man weighing 90 kg (198 lb), the Mifflin-St Jeor equation gives a BMR of 1,883 kcal/day, worked step by step below using a height of 178 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.

The late twenties are the decade when many people's daily activity quietly falls. Student life and entry-level jobs that kept you on your feet give way to desk work, commuting and longer sitting hours, while BMR itself barely changes — the equation subtracts only about 25–30 kcal between age 21 and age 27 at the same weight and height. The gap between what you burn and what you eat therefore opens up through activity, not through resting metabolism, and that is why the TDEE table below matters as much as the BMR figure itself.

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 25 to 29-year-old man at 90 kg and 178 cm:

  • 10 × 90 kg = 900 kcal
  • 6.25 × 178 cm = 1,113 kcal
  • 5 × 27 years = 135 kcal
  • Constant: + 5 kcal

So BMR = 900 + 1,113 − 135 + 5 = 1,883 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 (27 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
60 kg 1,582.5 kcal/day
70 kg 1,682.5 kcal/day
80 kg 1,782.5 kcal/day
90 kg 1,882.5 kcal/day
100 kg 1,982.5 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.

At 90 kg (198 lb) BMR is 1,883 kcal a day, which is a substantial resting burn: even a sedentary day costs 2,259 kcal, and a 500 kcal deficit still leaves 1,759 kcal, far above the 1,500 kcal safety floor. The BMI at this height and weight is 28.4, in the overweight range. The practical implication is that fat loss at this weight does not need a severe restriction — a moderate deficit plus daily walking and strength training is enough, and it preserves far more muscle than a crash diet.

How BMR changes with age

Holding weight (90 kg) and height (178 cm) fixed, the age term alone lowers BMR by 5 kcal a day for every year. The table below shows the same man's BMR at different ages:

Age BMR
21 years
32 years 1,857.5 kcal/day
42 years 1,807.5 kcal/day
52 years 1,757.5 kcal/day
62 years 1,707.5 kcal/day
68 years 1,677.5 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 25 to 29-year-old man at 90 kg:

| Activity level | Multiplier | TDEE | |---|---| | | Sedentary | 1.2 | 2,259 kcal/day | | Lightly active | 1.375 | 2,588 kcal/day | | Moderately active | 1.55 | 2,918 kcal/day | | Very active | 1.725 | 3,247 kcal/day | | Extremely active | 1.9 | 3,577 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 1,500 kcal a day (men) without medical supervision. For this person, a sedentary cutting target would be 1,759 kcal a day, a moderately active maintenance target would be 2,918 kcal a day, a moderately active cutting target would be 2,418 kcal a day, and a moderately active bulking target would be 3,218 kcal a day.

How to use the 1,883 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.

The most useful habit in this age band is a realistic activity choice. If you sit most of the day and train two or three times a week, you are lightly active, and using the moderately active multiplier inflates the target by roughly 200 kcal a day — enough to stall fat loss entirely. Set the target from the honest activity level, track food intake for two or three weeks, and adjust from the scale trend rather than from a single day. Strength training two or three times a week is the highest-return habit here: it defends the muscle that keeps BMR up as activity falls.

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 1,694–2,071 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.

The equation cannot see body composition, and that is its main weakness for this age band. Two people of the same sex, age, height and weight can have BMRs that differ by 10% or more if one lifts and the other does not, because muscle costs more energy at rest than fat. The figure below is a population-average estimate with an error band of roughly ±10%. If your body is unusually muscular or unusually low in muscle for your weight, treat the number as a starting point and correct it from measured intake and weight change over a few weeks.

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 25 to 29-year-old man weighing 90 kg?

Using the Mifflin-St Jeor equation with a height of 178 cm and age 27 years, BMR is 1,883 kcal/day: 10 × 90 + 6.25 × 178 − 5 × 27 + 5 = 1,883. 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 1,694–2,071 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.

Why is my BMR almost the same as it was at 21?

Because age subtracts only 5 kcal a day per year in the Mifflin-St Jeor equation. Between 21 and 27 that is about 30 kcal — too small to notice. If your weight is creeping up in your late twenties, the cause is almost always lower daily activity and higher intake, not a falling BMR. Check the activity multipliers in the TDEE table: dropping from moderately active to lightly active costs far more calories than six years of ageing.

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 2,418 kcal a day — 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 — 10 kcal of BMR per kilogram — so a deficit set months ago shrinks over time. At 90 kg, each 5 kg of weight change moves BMR by 50 kcal a day.

I sit all day but train hard three times a week — which activity level am I?

Lightly active, in most cases. The multipliers describe the whole week, not the workouts. Three hard sessions add real expenditure, but they do not cancel out forty-plus seated hours. Very active is for people who train hard most days or work physically demanding jobs. When in doubt, pick the lower level and adjust upward if weight falls faster than planned.

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.