AIS Sports Nutrition

Making Weight in Weight Category Sports

There are a number of sports in which competition is conducted with weight limits or classes. For the most part, the basic premise behind weight category sports is to match opponents of equal size and capability (in horse racing, the jockeys body mass is used to provide a handicap for the horse). However, in reality, many athletes will strive to compete in a weight class that is below their training weight to gain an advantage over smaller and lighter opponents. This has resulted in some athletes adopting “extreme” weight making practices which, rather than being discouraged, are culturally ingrained within the sport, such as exercising in sweat suits, fluid and energy restriction, diuretic and laxative use. This fact sheet outlines appropriate methods of managing body mass in weight-category sports.

Characteristics of weight-making sports

Within each weight category sport there are rules and regulations that dictate when and how often an athlete needs to weigh in, as well as the length of time between the weigh in and the competitive event. Additional characteristics within each sport will further determine the type and extent any weight making practices and the potential impact these will have on health and performance. These include:

  • The number of weight categories available
  • The frequency of competition
  • The physiological basis of the competition (i.e. the intensity and duration of the event)
  • The environment in which it is held (i.e. outside vs indoors, hot/humid vs cold)
  • The competition schedule (single vs a series of bouts, heats or finals)      

Assessment of the appropriate weight category

Objective anthropometric assessment (lean body mass, body fat, height, growth changes) should be used to help athletes assess the appropriate weight category in which they should compete. For example, an athlete who is 5 kg above their chosen weight category assessed as already having low body fat levels may be best advised to consider competing in the weight category above, especially if further growth is expected.  Anthropometric assessment should also be employed to objectively monitor changes in physique over time.
For younger athletes, allowances need to be made to account for possible further growth and maturation. This is especially important in the case where qualification events occur well in advance of major competitions. The athlete and support staff should be prepared to assess their ability to safely stay in a particular weight category for any length of time.
Anecdotally it would seem many athletes adopt an ad hoc approach to monitoring their weight e.g. weighing themselves at different times of day and on different sets of scales, thereby making accurate assessment of progress towards weight targets difficult.  Further, many also equate weight change which occurs during a training session due to sweat loss, as true weight loss.  By extension, they will restrict fluid intake during training to induce a greater fluid deficit, which will only compromise training performance, as well as increase susceptibility to opportunistic infection.  The most effective strategy to monitor weight is to weigh at the same time of day, on the same set of scales, preferably first thing in the morning before eating or drinking. Unless an athlete is competing in the next couple of weeks, weighing once a week is appropriate.

Minimum weight

In the late 1990’s, the governing body for college sport in the United States, the NCAA, implemented a number of rule changes designed to curb the extent of extreme weight making practices undertaken by collegiate wrestlers, one of which was the introduction of the minimum weight.  Under this rule, at the start of the pre-season wrestlers have their body fat percentage assessed, which is in turn used to determine the minimum weight at which they are allowed to compete. The minimum weight set is at 5% body fat for men and 12-14% for women.  Further, wrestlers are allowed only to lose a maximum of 2 pounds a week (~0.9 kg/wk) from the start of the pre-season to the date of their competition.

A 78 kg male wrestler is assessed as having a % body fat of 7.8%
Therefore, his fat free weight is  -   78 – (78 x 7.8%)
         = 78-6.9
         = 71.9 kg
Minimum weight        = 71.91/0.95
         = 75.7 kg 

Therefore, this athlete is not allowed to fight in a weight category below 75.7 kg

Long term weight management

Ideally, athletes should choose a competition weight class that is within 5% of a body mass (e.g.  ~70.4 - 71.1 kg for a boxer competing in the 69 kg weight class) which can be maintained by dietary and hydration practices that promote effective training, recovery and overall health. If athletes need to lose body mass to achieve their weight target, they should do so through long term moderate energy restriction and appropriate exercise. A moderate energy deficit (2000-4000 kJ/day) may help athletes achieve a weight loss of up to 0.5 kg/per week. A more marked energy deficit, achieved through severe energy restriction and/or through excessive exercise, will result in a greater loss of lean muscle tissue, which will have a negative effect on power to weight ratio and likely result in a greater rebound in weight once normal eating patterns have resumed. It is also more likely to reduce metabolic rate; increase the risk of bone resorption and reduce bone deposition, leading to lower bone density; impair growth and development in younger athletes; and restrict nutrient variety and increase the risk of nutrient deficiency.
Even when targeting loss of body mass, it is important that athletes still support the demands of training through appropriate nutrient intake. Diets should provide sufficient carbohydrate to fuel the demands of daily training (5-7 g/kg/body mass), with a focus on nutrient-dense options that also contribute to the athlete’s targets for other key micronutrients e.g. calcium and iron. Protein needs (1.2-1.5 g/kg/body mass) are usually easily met by consuming a mixed diet. The inclusion of a protein source at most meals and snacks will improve satiety, reduce the extent of loss of lean muscle tissue associated with restricted energy diets, and support training adaptations and regeneration of damaged tissues after training.
It is common for some athletes looking to reduce the overall energy intake to cut out the sports foods e.g. sports drink, liquid meal supplements, used to support key training sessions.  Such a practice may only serve to compromise training quality and increase susceptibility to opportunistic infection.  These athletes would be better served by reducing intake of energy-dense, low nutrient foods and fluids e.g. foods rich in saturated fat, alcohol, cordial and soft drink.

Acute weight loss strategies

Weight loss of 2-3% of a hydrated body mass in the 2-3 days before competition weigh-in should be tolerated by most athletes, especially if employed against a background of good nutrition and hydration practices. Strategies that can be used to achieve this include moderate energy restriction, manipulation of the residue content of the diet and mild restriction of fluid and sodium, combined with appropriate level of training, to achieve mild dehydration.

Energy restriction

Most athletes “taper” (or reduce training load) in the two weeks leading into a major competition. This reduction in energy expenditure needs to be matched by a drop in energy intake in order to sustain body mass loss leading into competition. As with long term weight management, a severe energy restriction at this stage is likely to be counter-productive.

Low residue diet

Switching from a normal dietary intake of moderate/high levels of fibre to a low fibre or residue meal plan can result in an acute body mass loss of 0.5g - 1 kg secondary to a reduction in the weight of the gastrointestinal contents.  This strategy will only be effective if undertaken against a background of a training diet that promoted adequate fibre intake.  Examples of food changes include changing multigrain to white bread, high fibre cereal to a low fibre cereal (e.g. rice bubbles), and reducing fruit and vegetable intakes.  A sports dietitian can assist in developing a meal plan specific to each athlete.

Manipulation of body water content

The creation of a fluid deficit, by deliberately inducing sweat and/or fluid loss from the body, whilst also restricting fluid intake, is one of the most commonly used acute weight making strategies used by athletes.  Ideally athletes will aim to induce sweat loss through exercise typically included in their normal training program, rather than other methods (e.g. sauna, laxatives, diuretics, extra exercise sessions) that can also result in fatigue and potentially have a more adverse effect on health and performance.  
During this time, athletes should focus on drinking fluids low in salt, such as water, cordial and juice. Drinking these fluids separate to food can help counter the increased fluid retention associated with the natural, or added, salt content of foods.

Other considerations

Athletes can expect to lose a small amount of body mass in the period between going to bed and waking in the morning.  They should assess this in the lead up to competition and account for it as part of their overall weight making strategy.


It is strongly recommended that athletes involved in weight category sports seek the advice of a suitably qualified sports dietitian to individualise their weight management plan, and short term weight-making techniques. Sports Dietitians can be located through the "find a sports dietitian" section of the Sports Dietitians Australia website

This fact sheet is based on AIS / National team athletes and is therefore specific to these athletes. Written by AIS Sports Nutrition, last updated March 2010. © Australian Sports Commission.

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