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Body Recomposition Calculator

A body recomposition calculator estimates the calories and protein you need to lose fat while building or keeping muscle at the same time. Unlike a weight-loss calculator, it targets calories at or just below maintenance rather than a steep deficit, because an aggressive deficit costs the muscle recomposition is meant to protect. This calculator estimates your maintenance needs from your height, weight, age, sex, and activity level, then sets a training-day and rest-day target plus a protein goal.

Sex

Used to select the published constant in the Mifflin-St Jeor equation, and to set the minimum daily intake this tool will display. If you enter a body fat percentage, the Katch-McArdle equation is used instead and this field stops affecting the calorie figures.

Height

Count deliberate training and the physical demand of your job. Most people who train a few times a week land on Moderate.

If you know it, we'll use a more precise equation and set your protein target from lean mass. If not, leave it blank.

Results update as you type. The button is here for keyboard and screen-reader users, and pressing Enter does the same thing.

Your inputs stay in your browser. Nothing you type here is sent to us, saved to an account, stored, or emailed. Like any page on this site, we do record that the page was visited.

Your targets appear here as soon as every required field is filled in. Body fat % is optional. Nothing is submitted, nothing is sent, and there is no email step.

Not for use during pregnancy or breastfeeding, under 18, or while being treated for an eating disorder. Talk to your physician first.

Educational only. This tool does not diagnose, prevent, treat, or cure any condition, and it is not medical advice or a recommendation of any specific therapy.

These numbers are estimates produced by a published equation. Individual needs vary. Talk with a licensed physician before making changes to how you eat, train, or take medication.

Using this calculator does not create a physician-patient relationship with Protocol MD.

Not for use during pregnancy or breastfeeding, under 18, or while being treated for an eating disorder. Talk to your physician first.

If tracking calories or weight feels compulsive or distressing, that is worth raising with a clinician. In the US you can text "NEDA" to 741741 to reach a trained volunteer at Crisis Text Line, any time.

Your inputs stay in your browser. Nothing you type here is sent to us, saved to an account, stored, or emailed. Like any page on this site, we do record that the page was visited.

Read our full guide to body recomposition

Start the physician-guided assessment

A calculator estimates energy needs. Whether anything beyond nutrition and training is appropriate for you is a question for a licensed physician.

How it works

How This Calculator Works

It runs in three steps. First it estimates your resting burn, the energy your body uses doing nothing at all. By default that uses the Mifflin-St Jeor equation, the standard for estimating resting energy expenditure from sex, age, height, and weight (Mifflin MD, et al., A new predictive equation for resting energy expenditure in healthy individuals, American Journal of Clinical Nutrition 1990).

If you enter a body fat percentage, it switches to Katch-McArdle instead, which calculates from lean body mass and ignores sex and age entirely. That is more precise when composition is actually known, because two people of the same sex, age, height, and weight can carry very different amounts of muscle, and muscle is what most of the resting burn is attached to.

Second, it multiplies that resting figure by an activity factor to estimate your total daily burn. Third, it sets your targets from that total: maintenance on training days, and about 10% below it on rest days. If you want the intermediate numbers on their own, the BMR calculator and the TDEE calculator show each step, and the rest of the free health calculators run entirely in your browser too.

The principle

Why Recomposition Calories Sit Near Maintenance

This is the one thing that separates this calculator from a weight-loss calculator, and it is worth being blunt about. A steep deficit does not selectively remove fat. It removes whatever your body is willing to give up, and without enough food and enough training stimulus, some of that is muscle. Recomposition is defined by keeping the muscle, so a large deficit is not an accelerated version of it. It is a different outcome.

That is why the targets above land where they do. Training days sit at maintenance, because that is when your body is being asked to repair and add tissue and has the least business being underfed. Rest days sit modestly below it, which is where the fat loss accumulates over weeks. The gap is small on purpose.

It also explains what this page deliberately does not offer: there is no fast option and no aggressive setting. If your goal is to drive the scale down as quickly as possible, that is a different objective with different arithmetic, and the calorie calculator is the honest place for it. Chasing both at once is how people end up lighter, weaker, and no leaner.

Nutrition

Why Protein Is the Real Output

The calorie figures get the attention, but protein is the number that decides whether recomposition happens. Protein supplies the amino acids your body uses to repair and build muscle, and when total intake is at or below maintenance it is what stops the body drawing on muscle instead of fat.

The range this calculator uses, roughly 0.7 to 1 gram per pound of body weight per day, comes from the resistance-training literature: a systematic review and meta-analysis found protein intake in that region meaningfully improved gains in muscle mass and strength (Morton RW, et al., A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults, British Journal of Sports Medicine 2018).

If you entered a body fat percentage, the target above is a single figure at about 1 gram per pound of lean mass instead. That is the more sensible basis, because it is the lean tissue you are feeding, not the fat. Someone carrying a lot of body fat does not need protein for the fat.

Protein Without Training Does Not Work Either

Protein is the raw material; resistance training is the signal that tells your body to spend it on muscle rather than discard it. Neither does the job alone, which is why every figure on this page assumes consistent resistance training. Without it, this is a maintenance calorie calculator with a high protein target.

Timeline

How Long Body Recomposition Takes

Months, not weeks. Often six months to a year or more for a change dramatic enough that other people notice, because you are asking your body to do two demanding things at once and progress on each is slower than if you chased only one.

The practical consequence is that the scale is close to useless as a progress metric here. If you lose three pounds of fat and add three pounds of muscle over a month, the scale reports nothing happened. Track photographs taken in the same light, tape measurements, how clothes fit, and what you can lift. Those move when recomposition is working and the scale is flat.

Our full guide to body recomposition covers the training and nutrition side in more depth, and the BMI calculator gives a starting reference point, with a clear account of what that number cannot tell you about composition.

Who it suits

Who Recomposition Works Best For

Three groups see it happen fastest: people new to resistance training, people returning after a long break, and people carrying more body fat to start. In each case the body has both a strong adaptive response to training and, in the third, ample stored energy to fund muscle repair while fat comes off.

Lean, already-trained individuals can still recompose, but the margins get fine and the timeline stretches. The closer you already are to your genetic ceiling, the more precisely the calories, protein, training, and sleep all have to line up, and the more likely it is that dedicated phases work better than trying to do both at once indefinitely.

None of that is a reason not to try. It is a reason to judge progress over months rather than weeks, and to expect a beginner's first six months to look different from an experienced lifter's.

Questions

Frequently Asked Questions

How many calories should I eat for body recomposition?

Most people do best at or slightly below maintenance — often maintenance on training days and roughly 10% below on rest days. A steep deficit tends to cost muscle, which works against recomposition. This calculator estimates your maintenance and sets both targets.

How much protein do I need for body recomposition?

A commonly used evidence-based range is 0.7 to 1 gram per pound of body weight daily, or about 1 gram per pound of lean body mass if you know your body fat percentage. Protein is what protects muscle while you lose fat.

Is this different from a weight loss calculator?

Yes. A weight-loss calculator sets a deliberate deficit to drive the scale down. A recomposition calculator keeps calories near maintenance so your body can build or hold muscle while fat comes off, which changes your composition even when your weight barely moves.

Do I need to know my body fat percentage?

No. Without it we use the Mifflin-St Jeor equation, which is the standard. If you do know it, we use Katch-McArdle instead and base your protein target on lean mass, which is more precise.

How long does body recomposition take?

Months rather than weeks, often six months to a year or more for a dramatic change, because you are asking your body to do two demanding things at once. Beginners and those with more body fat typically see visible change sooner.

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Educational only. This tool does not diagnose, prevent, treat, or cure any condition, and it is not medical advice or a recommendation of any specific therapy.

Using this calculator does not create a physician-patient relationship with Protocol MD.