Title: Boxers and Bodyweight Manipulation

Key words: calorie restriction, increased exercise, dehydration, rehydration, isokinetic performance, dietary manipulation, electrolyte balance

Date: Aug 2000

Category:  12. Sports

Type: Article

Author: Dr van Rhijn



Boxers and Bodyweight Manipulation



A strong coaching philosophy exists among amateur boxers to ‘make weight’ prior to contests, aiming entry at the lowest weight category possible without impairing performance or health. The extreme methods used to achieve official weight and avoid disqualification can have serious consequences.


Methods Employed

Numerous, non-standardised techniques are utilized to achieve target bodyweight, which poses an enormous challenge as normal living weight can be up to 9 kg more than international competition weight. Combinations of techniques are usually used, with increased intensity as the weigh-in date approaches. Unfortunately, many athletes and coaches are not properly supervised by experienced dieticians.



Rapid weight reduction by means of dietary calorie restriction is approached individually according to habits and rituals, often based on non-scientific misconceptions regarding appropriate diets for athletes, such as carbohydrate restriction and increased protein intake. Gradual bodyweight reduction is achieved by reducing energy intake to 75 – 130 kJ/kg/day, as a negative energy balance of 100 kJ/kg/day results in a weekly bodyweight loss of 1 kg1.



Active methods include increased exercise (especially in plastic or rubber suits) such as running, gym workouts and even masturbation. 



Rapid bodyweight reduction is achieved by passive methods such as fluid restriction (12-96 hours), intermittent sauna (80oC), environmental chambers (56oC), self-induced vomiting, enemas, laxatives and diuretics2 (unethical & illegal?). More drastic measures (blood transfusions) have also been resorted to, with the aim of shedding the most difficult, final 0.5-1.0 kg.


Amateur wrestlers lose on average 3.1 kg (5.5% BW) in the final 10 days before a competition (4.5–4.9% in the last 12-24 hours)3, and regain on average 6.2 kg (11% BW) four months post-season4.


Rehydration strategies between weigh-in and competition are time dependent as it may take 5-20 hours to recover from dehydration. It requires careful, individually fine-tuned, planned replacement strategy of water, electrolytes and carbohydrate loading for energy. Reported magnitude of bodyweight gain (% BW loss) is variable, and measured between 21% (1 hour) to 100% (3-5 hours) before competition5.


Many athletes who were dehydrated (urinary profiles) during the weigh-in period were still dehydrated during competition (5 hours after making weight) clearly unable to rehydrate or restore electrolyte balances6 - especially the associated urinary potassium loss during dehydration7. Rapid bodyweight reduction should not exceed 4% BW if the time between weigh-in and competition is < 5 hours. 


Effects on Performance

Aerobic endurance capacity and muscle strength (isokinetic performance) decreases after rapid bodyweight reduction8 despite rehydration for 3-4 hours prior to competition. This decreased performance could be explained by hypoglycaemia, reduction in plasma volume9,10,11, cardiac output and stroke volume, limiting oxygen transportation to demanding muscles. Anaerobic work may be affected by glycogen depletion12 (weight cycling13 / negative calorie balance14,15), decreased base excess16,17, slow nutrient exchange, increased urea, waste removal and heat dissipation18. Dietary manipulation may compromise micronutrients, resulting in vitamin (C, A, B1, B6 ) and mineral (Fe, Mg, Zn, Cu)19 deficiencies, which can adversely affect performance via numerous biochemical and metabolic processes. Na and Mg losses may be substantial via sweating20. Testosterone levels in wrestlers21 were lower during season, potentially impeding growth22. Psychological factors, such as mood alterations23, anger or anxiety during weight reducing attempts may also affect performance.


Performance is not adversely affected and may even be improved during gradual weight reduction, and longer time periods (> 5 hours) between weigh-in and competition to allow for rehydration. High carbohydrate diets (60-70%)24 prevent catabolism of protein25 as a fuel source, which may be better utilized for muscle repair.



As weight control will remain an integral part of boxing, adequate understanding regarding basic nutritional principles26,27 is recommended to ensure safely conducted weight control. Improved rules will avoid crash diets, reduce the risk of dehydration and protect the susceptible brain from injury.



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