TDEEHQ

Age-adjusted · Free · No sign-up

TDEE Calculator for Adults Over 40

Standard calculators treat a 55-year-old like a 25-year-old with a slightly smaller BMR. Your body did not get that memo. This version runs the normal maths first, then corrects for the muscle loss and lower everyday movement that creep in after 40 — unless your training says otherwise.

1–2% / yr
muscle lost after 40 without lifting
150–300
kcal/day the formula can overshoot
0–7%
adjustment range applied here
1.8–2.2 g
protein per kg we recommend

Your stats

Standard inputs first — the age adjustment is applied below.

Biological sex
yrs
lb
Height
ft
in
%

Age & training adjustment

Pick your decade and how you train. Lifting regularly removes most of the penalty; the formula already includes an age term, so the extra correction is deliberately small.

No change
Your decade
How you train

No downward adjustment — regular lifting keeps your lean mass, and your TDEE, close to the formula.

Estimates are typically within ±10%. Track your weight for two weeks and adjust by 100–200 kcal.

The context

What changes about TDEE after 40?

Total Daily Energy Expenditure is still the same idea at 45 as at 25: the calories you burn in a day across resting metabolism, digestion, everyday movement and exercise. What changes is the mix. Mifflin-St Jeor subtracts five calories per year of age, which captures the slow decline in resting burn — but it assumes your body composition and movement habits look like the population average for your age.

For many adults past 40, they do not. Muscle quietly declines, spontaneous movement drops, sleep gets lighter and hormones shift. Each effect is small; stacked across a decade they can leave your true burn 150–300 kcal a day below the textbook number. Eat to the textbook and you gain weight “for no reason”. This page corrects for that — and, just as importantly, tells you when no correction is needed.

Why the formula drifts

Six levers that matter more after 40

The same inputs drive TDEE at any age. These are the ones whose weight shifts in midlife.

01

Muscle mass

Each kilogram of muscle burns roughly 13 kcal a day at rest versus about 4 for fat. Lose a kilo a year for a decade and your BMR has lost more than a hundred calories a day.

02

Everyday movement (NEAT)

Fidgeting, standing, pacing, chores. NEAT drifts down with age even in people who still train — and it is the component that varies most between two otherwise similar adults.

03

Hormonal shifts

Testosterone declines about 1% a year after 30; oestrogen falls steeply around menopause. Both make muscle harder to hold and shift fat storage toward the midsection.

04

Insulin sensitivity

Carbohydrate handling tends to worsen without regular exercise, nudging calories toward storage. Lifting and walking are the two most reliable fixes.

05

Sleep architecture

Deep sleep shrinks with age. Poor sleep raises cortisol, lowers growth hormone and quietly suppresses the next day’s NEAT.

06

Stress & cortisol

Chronic stress breaks down muscle, promotes abdominal fat and dampens thyroid output — none of which a formula can see.

Decade by decade

How the picture shifts by decade

Averages, not destiny. Resistance training flattens almost every one of these curves.

  1. 40s

    Stage 1

    Early drift

    Muscle loss begins in earnest for the untrained. NEAT starts to dip as careers and family compress free movement. Fully reversible with two lifting sessions a week.

  2. 50s

    Stage 2

    Hormones join in

    Menopause and falling testosterone speed up the loss of lean mass. Recovery slows, so training volume should be smarter, not necessarily higher.

  3. 60s

    Stage 3

    Sarcopenia risk

    Without lifting, strength and muscle can fall 3% a year. Protein per meal matters more because older muscle responds less to small doses.

  4. 70+

    Stage 4

    Preserve, then build

    Holding lean mass is the goal; building it is still possible. Aggressive deficits are counter-productive — moderate deficit, high protein, consistent lifting.

Method

How this calculator gets to your number

Three steps. The first two are the standard TDEE method; the third is what makes this page different.

Run it with my numbers
  1. 1

    Resting burn (BMR)

    Mifflin-St Jeor with your real age, sex, height and weight. If you know your body fat, we switch to Katch-McArdle — the better fit for people who have kept their muscle.

  2. 2

    Activity multiplier

    Be honest here. Many people over 40 grade themselves against their younger selves. Three gym sessions a week with under 6,000 daily steps is “lightly active”, not “moderately active” — a one-tier mistake adds 200–300 kcal.

  3. 3

    Age & training adjustment

    A multiplier between 0.93 and 1.00 based on your decade and whether you lift. Lifters in their 40s get no adjustment at all. The values are drawn from resting-metabolic-rate studies in ageing populations and kept deliberately conservative.

Pick a direction

Setting goals after 40

The order of priorities flips: keep (or rebuild) muscle first, lose fat second. Calorie targets should be gentler than the textbook.

−300 kcal / day

Lose fat, keep muscle

— —kcal / day

A modest deficit with protein at the top of the range preserves far more lean mass than a bigger cut. Expect 0.25–0.4 kg a week and plan for 12–16 weeks rather than six.

Get my number
Eat at TDEE

Recomposition

— —kcal / day

If you are new to lifting or returning after years off, eating at maintenance while training hard can lose fat and add muscle simultaneously. Track body fat, not the scale.

Get my number
+250 kcal / day

Rebuild muscle

— —kcal / day

A small surplus plus heavy compound lifts and 2 g protein per kg still builds real tissue after 40. Larger surpluses mostly add fat at this age.

Get my number

Highest return first

What pays back most after 40

Ranked by return on effort. None of them require more hours in the gym.

  1. #1

    Lift before you run

    Cardio burns calories while you do it. Lifting raises resting burn for 24–48 hours and, over months, adds the muscle that raises BMR permanently. If you only have two sessions a week, make them resistance training.

  2. #2

    Front-load protein per meal

    Older muscle needs a bigger dose to trigger growth — roughly 35–45 g per meal rather than 20. Aim for 1.8–2.2 g per kg across the day.

  3. #3

    Buy back your NEAT with steps

    An extra 2,000 steps a day is worth about 100 kcal — with no workout. 7,000–10,000 daily steps outside of training is the most reliable NEAT target.

  4. #4

    Treat sleep as training

    Seven-plus hours protects testosterone, growth hormone and tomorrow’s movement. Nothing else on this list works well on five hours.

  5. #5

    Cut alcohol before carbs

    Alcohol is burned first, pausing fat oxidation while it is processed. After 40 that shows up as abdominal fat because cortisol already steers storage there.

  6. #6

    Recalculate quarterly

    Body composition changes more slowly but more consistently in one direction without intervention. Re-run this page every 3–4 months and adjust by 100–150 kcal.

FAQ

Questions about TDEE over 40

Short, direct answers. If yours is missing, ask and we will add it.

Ask a question

Mostly because of body composition, not age itself. Adults who stop resistance training lose 1–2% of muscle a year, and muscle is the most metabolically active tissue you control. Everyday movement (NEAT) also drifts down. Hormonal changes contribute, but they are secondary to muscle loss for most people — which is why lifters in their 40s need no adjustment on this calculator.

Keep going

Related calculators & guides

Back to the main TDEE calculator

Main TDEE calculator

Homepage tool — Mifflin-St Jeor with optional body fat.

What makes up TDEE

BMR, NEAT, TEF and exercise explained.

Which formula to trust

Mifflin-St Jeor vs Katch-McArdle.

Goals from your number

Cut, maintain, or build from TDEE.

Two minutes

Get your age-adjusted number now.

Calculate adjusted TDEE