Fighter nutrition in camp: calories, weight and rehydration

The question coaches hear in week one of camp is almost never about protein. It is "how much can I eat and still make weight?" The honest answer tends to disappoint: most fighters in camp eat less than they need and plan to strip off far more weight than is sensible.

A six to ten week camp asks for three things that pull against each other — train hard, recover between sessions, and arrive at a contracted weight. Food is the only tool that holds all three together.

What camp actually costs in energy

A fighter doing nine to twelve sessions a week — sparring, technical work, conditioning, gym — burns far more than a recreational athlete training three times. Total daily expenditure for lighter weight classes usually sits somewhere around 2,800 to 3,200 kcal, and above 4,000 kcal for heavier fighters.

Those figures are a starting point, not a prescription. It is more useful to work from body mass: 40 to 50 kcal per kilogram on two-session days, 30 to 35 kcal on rest or light days. Two weeks of scale readings and how sparring feels will tell you whether the estimate was close.

If fat loss is also on the list, a deficit of 300 to 500 kcal a day is about the ceiling that camp tolerates. Anything larger usually gets paid back as a thinner gas tank in rounds four and five and slower recovery between hard sessions.

Protein, carbohydrate and fat

• Protein: 1.6 to 2.2 g per kilogram of body mass per day, moving towards the top of that range — even 2.4 g/kg — while in a deficit, because higher intakes protect muscle as fat comes off.
• Carbohydrate: 4 to 7 g/kg on hard sparring or conditioning days, 3 to 4 g/kg on light ones. This is the number that should move day to day.
• Fat: not below roughly 0.8 g/kg. Go under that and hormones, sleep and mood suffer, which shows up in training before it shows up anywhere else.

Everything else is detail. Meal timing, breakfast, so-called protein windows — they all do something, but far less than whether the fighter is eating enough at all.

The discipline matters too. A week built around traditional muay thai training, with long rounds on the bag and heavy clinch work, costs noticeably more energy than a week spent on positional technique and drilling. The same athlete can swing 400 to 600 kcal a day between those two weeks.

What a week looks like in practice

Take a fighter who walks around at 75 kg and competes at 70 kg. Camp gives them two sparring sessions, two strength sessions and three technical sessions a week. That week should not look like seven identical days.

On a sparring day they eat around 3,400 kcal with 400 g of carbohydrate: a proper meal three hours out (1 to 1.5 g/kg of carbohydrate), something light and easy 45 minutes before, and a real meal with 30 to 40 g of protein within an hour afterwards. On a rest day they drop to about 2,600 kcal and 200 g of carbohydrate, with protein unchanged.

When a week mixes grappling and striking sessions, the hard days are spaced so at least 48 hours sit between the two heaviest. Food follows that schedule rather than the other way round.

Fluid gets tracked as carefully as food. Losing one to two kilograms in a hard session is normal; the trouble starts when it is not replaced by the next morning and the shortfall carries through the week. Weigh in before and after training, then drink roughly 1.25 litres per kilogram lost and salt the next meal.

Cutting fat and cutting water are two different jobs

This is where most of the damage happens. Fat loss is slow work spread across the whole camp — 0.5 to 1 per cent of body mass a week, so 400 to 800 grams for a 75 kg fighter. A water cut is an acute procedure in the final 24 to 48 hours before the scales, and has nothing to do with body fat.

A sane plan looks like this: start camp no more than 8 to 10 per cent above the limit, come down gradually to 4 to 5 per cent above, and let water handle the rest. A fighter facing 8 kg of water on weigh-in day is not preparing for a contest, they are preparing for trouble. The mechanics and the limits are covered in more depth in the piece on cutting weight before the weigh-in.

The gap between the scales and the first bell changes everything. With 24 to 30 hours, most of the lost fluid and glycogen genuinely comes back. With a same-morning weigh-in, an aggressive cut means walking out dehydrated — less endurance, slower reactions, and a brain with less fluid cushioning it.

Rehydration: the first four hours decide it

Nobody should sink a litre of water the moment they step off the scales. Most of it leaves as urine before the body can use it.

The method is duller and works better: 1.25 to 1.5 litres of fluid per kilogram lost, spread over several hours in 200 to 300 ml sips every 15 to 20 minutes. The fluid needs sodium in it, since plain water is largely passed straight through. Alongside that, aim for 1 to 1.2 g of carbohydrate per kilogram per hour for the first three to four hours, because glycogen and water are restored together.

Keep the food familiar and easy: rice, pasta, white bread, fruit, a modest portion of meat or fish. Camp is a poor time to try new dishes, and the hour after a weigh-in is the worst time of all. Fat and fibre stay low because they slow the stomach down.

Common misconceptions

• Eating less makes me sharper. An oversized deficit takes sparring quality first, then strength, then sleep. The scale moves and the performance gets worse.
• Carbs bloat me, so I cut them. Low carbohydrate intake is fine on easy days. On a hard sparring day you feel the difference by round three.
• The sauna is part of the sport and the body adapts. It does not. Repeated severe dehydration is one of the more serious risks in combat sports, and repetition does not make it safer.
• Salt is bad, so I cut it before a fight. Sodium is precisely what keeps rehydration fluid where it is needed after the weigh-in. Without it, recovery takes considerably longer.
• Supplements fill the gaps. The evidence is strongest for very ordinary things — creatine, caffeine, enough protein from food. The rest mostly sells well, and none of it fixes missing sleep or missing calories.

When to see a doctor

Get proper medical advice if you get dizzy standing up, cramp that will not settle, dark urine in small volumes, a resting heart rate that stays elevated for several days, or a missed menstrual cycle. The same applies if weight stalls despite a clear deficit, if sleep has fallen apart, or if small injuries start stacking up. Young athletes still growing, and anyone with diabetes, kidney or heart conditions, should not attempt a water cut without medical supervision.

In short

• Camp costs roughly 2,800 to 4,000 kcal a day; deficits beyond 500 kcal are paid for in sparring.
• Protein 1.6–2.2 g/kg, carbohydrate 4–7 g/kg on hard days, fat no lower than 0.8 g/kg.
• Fat comes off slowly across the whole camp, at 0.5 to 1 per cent of body mass per week.
• Start camp no more than 8 to 10 per cent above the limit; leave the remainder to the final two days.
• Rehydrate with 1.25–1.5 litres per kilogram lost, with sodium and carbohydrate, in small sips.
• The shorter the gap between weigh-in and fight, the smaller the water cut has to be.