How many calories does a fighter need in camp?

Calories on their own cannot answer this. A fighter eating 3,000 a day can be in worse shape than one eating 2,000, and the reason is a number almost nobody in a gym has heard of.

The question always arrives the same way. How many calories should I be on.

What the person means is: give me a target so I stop guessing. Fair. But a single figure is the wrong instrument, and I can show you why with two numbers from published research rather than by arguing about it.

Why the calorie number alone tells you nothing

Two fighters. Both 75 kg. Both eating 3,000 kcal a day.

Per-kilogram guidance produces very different absolute numbers at the top of the sport, and the division where that becomes a practical obstacle is covered in heavyweights.

Where that protein comes from is a separate question, and powder is the most common shortcut: what protein powder is worth covers whether it earns its place.

One trains 90 minutes and burns 600. The other does 2 sessions, sparring in the morning and conditioning in the evening, and burns 1,400.

Identical diets. One of them has 2,400 kcal left over to run a body with. The other has 1,600, and he is the one who also has to repair the damage from harder work.

That leftover is the thing that matters, and it has a name.

Energy availability

Energy availability is what remains after training is paid for, expressed per kilogram of fat-free mass. Intake minus the cost of exercise, divided by the lean tissue that has to be kept alive.

The thresholds used in the literature:

These cut-points were established in female athletes. Male-specific thresholds have not been determined, and the female values are applied in male studies for want of anything better. Read the numbers with that in mind.

The calculation, done once with numbers

The formula is easy to state and awkward to apply, so here it is applied.

Take a 77 kg fighter at 12 percent body fat. His fat-free mass is 68 kg. On a hard day he eats 2,900 kcal and his training costs 900 kcal above what he would have burned sitting still.

Twenty-nine. Below the line, on a day he considered normal, eating what most people would call a lot of food.

That is the whole problem in one arithmetic. Nothing about 2,900 kcal looks like under-eating until you subtract what the training took and divide by the tissue that has to be maintained.

Two things the example shows that the formula does not.

The training cost is the number people get wrong. It is the cost of the session above resting metabolism, not the figure a watch reports, and watches overstate it substantially in intermittent sport.

If you are guessing, guess low, because guessing high makes the answer look better than it is.

Fat-free mass, not body weight. Using 77 instead of 68 in that calculation gives 26 rather than 29, and both are wrong in the same direction as the fighter's optimism.

Run it on your own worst day rather than your average one. The average is not what damages you.

Where combat athletes actually sit

A study of 30 state-level lightweight boxers measured intake, exercise expenditure and body composition across 3 days. Mean energy availability was 29.7 kcal/kg FFM/day in the men and 28.3 in the women.

Around two thirds of the group were classified as low.

Not in fight week. In ordinary training.

Their intake fell short of requirements by 29% for energy, 36% for carbohydrate and 35% for protein.

I include that second figure because pretending it does not happen would be dishonest. It happens at every level. What I would not do is read it as permission, because the case report describes what an elite athlete survived, not what a camp should be built on.

The first numbers from a male fighter

The thresholds above were established in female athletes, and this site has said so for as long as it has existed. There is now one detailed set of measurements from a male combat athlete, and the picture it gives is more complicated than a simple transfer of the female numbers.

A case study published in Medicine and Science in Sports and Exercise followed one male combat sport athlete across 8 weeks, measuring body composition, resting metabolic rate, cardiac function, strength and power, psychological state and blood chemistry throughout.

Read the top row against the table earlier on this page. Twenty is beneath the 30 mark that classifies low energy availability in the female-derived scheme, and across 7 weeks it produced no measurable harm in this athlete.

Read the bottom row and the picture reverses. Five days is not long, and below 10 the markers moved fast.

It also tells you where to look. If a fighter is going to show endocrine and metabolic consequences, the final week is where they appear, not the 8 weeks of camp that preceded it.

That is the opposite of where most attention goes.

The floors nobody should go under

Energy availability tells you whether the total is enough. It does not tell you whether the composition is, and a camp can pass one test while failing the other.

The 2025 ISSN position stand on combat sports sets floors below which macronutrients should not fall during a longitudinal weight descent.

Read those as the bottom of the range rather than the plan. The stand is explicit that protein should be prioritised during a weight descent to preserve lean mass, and that carbohydrate delivery has to match training demands rather than a fixed number.

On a 77 kg fighter the carbohydrate floor is around 230 to 310 grams a day. Camps routinely run below that in the final weeks, and the athlete then wonders why the last 2 rounds of sparring have gone missing.

What being under the line does

The body responds to a sustained shortfall by spending less. That sounds like an advantage in a weight-class sport. It is the opposite.

• Resting metabolic rate falls. The engine turns itself down, which means the same food that used to produce a deficit stops producing one, and the next camp starts from a worse place.
• Thyroid hormones drop. T3 and free T3 decline, which is part of the same mechanism.
• In women, reproductive function is affected below 30 kcal/kg FFM/day, including reduced estradiol and functional hypothalamic amenorrhoea.
• Bone, immune function, mood and sleep all sit downstream of the same shortfall.

A fighter who cycles through this repeatedly ends up with a body that defends its weight harder every year. Then somebody tells him he lacks discipline.

So how do you actually set the number

Estimate the floor, then check the leftover. Two steps, in that order.

The floor. Resting metabolic rate can be estimated from lean body mass with the Cunningham equation, 500 plus 22 times lean mass in kilograms, or from age, sex, height and weight with Mifflin-St Jeor. Both appear in the International Society of Sports Nutrition position stand on combat sports. Neither is exact.

Both are close enough to start.

The leftover. Add the real cost of your training week, not a guess from an app, and see what is left per kilogram of lean mass. If that figure is under 30 while you are still 8 weeks out, the camp has a problem that no amount of extra sparring will fix.

The point of doing it this way round is that the calorie target falls out of the arithmetic instead of being chosen first and defended afterwards.

The problem sitting at the centre of every camp

Training load peaks in the middle weeks. So does the energy cost of it.

That is also when most fighters start eating less, because the weigh-in is getting closer and the scale is not moving fast enough.

Two curves going in opposite directions at the exact moment the athlete needs to be absorbing the hardest work of the whole preparation. Almost every camp I have been asked to rescue was in that shape, and the fix is never a new supplement.

It is moving the weight loss earlier and letting the middle of camp be properly fed.

That is the whole argument for planning a camp as a performance programme that contains a weight cut, rather than a diet with training attached.

What I would check first

Are you still getting stronger in week five. If the numbers in the gym have gone backwards, the shortfall is already showing and no scale reading makes that acceptable.

Is sleep intact. Waking at four in the morning during a hard block is a signal, not a coincidence, and the hours you lose there cost more than the food you saved.

Is the weight moving without you changing anything. That is metabolic adaptation announcing itself.

Are the hard days actually different from the rest days. Eating the same on both is the most common structural error I see, and it underfuels the work while overfeeding the recovery.

The version I would give a coach

Stop asking what the number is. Ask what is left after training.

A fighter who is fed properly through the middle of camp arrives at fight week with something to spend. One who has been running on empty since week two arrives having already spent it, and the last 7 days are where that bill gets presented, in front of everybody.

Fighters who cannot make weight often reach for a diet rather than a number. Why that particular diet is the wrong answer here is in keto for fighters.

If you are using a body fat percentage as one of your inputs, read what that number is worth first: body composition.