Judo nutrition: weight categories and competition

Why does rapid weight cutting reduce performance?

Acute weight cutting means losing several kilos in a few days by restricting food and water, using a sauna or training in thermal clothing. It is widespread in combat sports. A review of Olympic combat sports warns that taking it to extremes is dangerous to health [2]. It also explains that how much weight can be lost and regained depends on the time between weigh-in and the bout [2].

Most of what you lose over those days is body water and muscle glycogen, the muscle’s energy reserve. The joint sports nutrition guidance from the United States and Canada notes that losing more than 2% of body weight as water can impair mental function and aerobic performance [1]. Strength, power and technique are particularly affected from 3–5% onwards [1]. In judo, a fraction of a second in the grip can decide the bout.

Dehydrating yourself to make weight also leaves a fluid deficit that is difficult to recover from before competing [1]. Heat combined with dehydration increases the risk of heatstroke [1].

How to choose your category before the season

Your weight category should be chosen according to your height, muscle mass and body fat. Choosing the category that looks easiest on paper is a poor basis for deciding. Competing in a category that forces you to restrict your intake for months leads to chronic fatigue and muscle loss.

If you need to lose weight, do it during the base phase of the season, well before competition, with a moderate energy deficit. According to the joint sports nutrition guidance from the United States and Canada, muscle and performance are better preserved when you lose less than 1% of your body weight per week [1]. For a 70 kg judoka, that is less than 700 g a week.

If your natural weight is above the limit, moving up a category and gaining muscle with a plan is another option. We can work on this in a weight-gain dietitian consultation.

How much carbohydrate and protein does a judoka need?

During training weeks, the same joint guidance recommends 5–7 g of carbohydrate per kilogram of body weight per day for a moderate programme of around one hour a day [1]. With one to three hours a day of moderate- to high-intensity training, the amount rises to 6–10 g [1].

The recommended protein intake is 1.4–2.0 g per kilogram of body weight per day [4]. Strength-trained people in an energy deficit may need 2.3–3.1 g to preserve muscle [4].

Fat should not be kept below 20% of energy intake over a sustained period, as this can lead to inadequate fat-soluble vitamins and essential fatty acids [1]. The sports nutrition guide covers the general foundations of performance.

What should you eat in the days before weigh-in?

The International Judo Federation rules set the official weigh-in for the afternoon before the competition [3]. There is a random weigh-in on the same morning, at which you must not exceed your category limit by more than 5% [3]. Having the night to recover is valuable, but it does not justify dehydrating yourself in the preceding days. The timing may differ at national or grassroots tournaments.

To adjust the final few grams without affecting muscle or resorting to diuretics, a review of combat sports describes reducing gut contents [2]. In practice, this means a low-residue diet in the days before the scales. Replace wholegrains, pulses and fibrous vegetables with white rice, refined pasta, and lean meat or fish, while still eating enough.

Keep drinking water. If you are a few hundred grams over on weigh-in day, adjust the amount of fluid in the final hours; never use a sauna or diuretics.

How should you recover immediately after making weight?

Stepping off the scales brings immediate relief. Overeating and choosing fatty foods at that point often lead to nausea, heaviness and slow digestion that spoil your rest. Recovery happens in stages.

For fluid, the joint sports nutrition guidance from the United States and Canada recommends 1.25 to 1.5 litres for every kilogram lost [1]. Spread it over several drinks, as some will be lost in urine. Do not restrict sodium during this phase; it helps you retain fluid [1]. Drinking a large amount of plain water without sodium can cause hyponatraemia, a dangerous fall in blood sodium [1].

To replenish glycogen after an afternoon weigh-in the day before, have a generous portion of white rice or boiled potatoes for dinner, with grilled chicken or white fish and a ripe piece of fruit. If weigh-in is on the same day and you have less than eight hours before competing, time is short. In that case, aim for 1 to 1.2 g of carbohydrate per kilogram per hour during the first four hours, in small, frequent servings [1]. Pair it with around 0.25 g of protein per kilogram, or 20 to 40 g per serving, to stimulate muscle protein synthesis [4].

On competition morning, have 1 to 4 g of carbohydrate per kilogram one to four hours beforehand, choosing foods low in fat and fibre [1]. For fluid, have 5 to 10 ml per kilogram two to four hours beforehand [1]—350 to 700 ml if you weigh 70 kg.

Between bouts: what to eat and drink during a tournament

A judo tournament is organised around eliminations and repechage rounds. You may have several bouts throughout the day, with irregular breaks, so it is not the time for large meals that take a long time to digest.

For intermittent exercise lasting one to two and a half hours, the joint guidance recommends 30 to 60 g of carbohydrate per hour [1]. At a tournament, spread this across the breaks. Easy-to-digest options between bouts include sips of an isotonic drink, half a very ripe banana, a small handful of raisins or cereal porridge. If you have more than two hours between bouts, a small white-bread sandwich with turkey or quince paste is suitable.

Do not drink during a bout. Take small, frequent sips after leaving the tatami and during the warm-up for the next bout. Pale-yellow urine indicates that you are well hydrated [1].

Do you need supplements to perform well in judo?

No. You do not need protein shakes or bars to perform well in judo. You can get enough protein from food at your main meals, and no supplement can replace good planning.

Few supplements have strong evidence behind them, and there is a risk of contamination with banned substances and of a sanction [1]. No sports supplements for minors; their use is not justified [1].

When making weight becomes a problem

Repeating cycles of rapid weight loss and regain over many years takes a toll on the body. The International Olympic Committee consensus describes this as Relative Energy Deficiency in Sport (REDs). It occurs when what you eat does not cover what you use in training and what your body needs to function [5]. Over time, it disrupts hormones, compromises bone health and increases the risk of injury [5].

In women, loss of periods and stress fractures are warning signs. Men can also experience hormonal and bone effects, although they may be less noticeable [5].

Weight-category sports also carry a higher risk of eating disorders [5]. If making weight causes ongoing distress, fear of eating, purging behaviours or social isolation, seek help from a psychologist specialising in this area. Matching your category to your physical reality is the first step towards protecting your health and extending your sporting career.

What mistakes do we see most often in consultations?

• Choosing a category by looking at the field of opponents. If every tournament means a week of sauna use, that category is not right for your body.
• Trying unfamiliar food on competition day. A gel or bar you have never tried may upset your stomach just before you step onto the tatami.
• Copying a club-mate’s weight-cutting plan. What works for another category, another body and a different weigh-in time cannot simply be transferred to you.
• Treating persistent fatigue or missed periods as part of the sacrifice. These are reasons to seek a medical appointment.