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Weight cutting and your kidneys
Your kidneys are two fist sized organs, each shaped like a bean. They lie either side of the spine, just below the rib cage. Their main function of the kidneys is to filter the blood and to regulate what is in your circulatory system. They eliminate waste products, control blood pressure, and balance levels of electrolytes (salts).
As MMA has become increasingly competitive over the last decade, the practice of weight cutting has grown in popularity. One of the most common strategies for short-term weight loss is dehydration. Fighters often restrict their fluid intake over the 24-48 hours prior to the weigh-in, and many use saunas and/or exercise to dehydrate themselves further.
When an athlete becomes dehydrated the blood flow to the kidney drops. Take this too far and the kidneys may stop functioning or become damaged, and acute kidney injury (also known as “acute renal failure”) can set in. Warning signs include dry mouth, low urine output and lethargy – things that many fighters regard as normal when cutting weight. Symptoms of renal failure include nausea, shortness of breath, drowsiness, confusion, pain in the back and chest pain. As it becomes more severe, there may be swelling in the legs, and even seizures or loss of consciousness.
Taking non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, diclofenac or naproxen – medicines which are commonly used by fighters for management of minor injuries in the run up to a fight – are thought to increase the risk of kidney failure in the presence of dehydration. Certain performance enhancing drugs may also increase the risk. Diuretics that increase the amount of urine produced are sometimes misused by fighters attempting to drop large amounts of water weight. Their use may increase the risk of kidney damage during the weight cutting process. Anabolic steroid use has also been shown to cause scarring and loss of function within the kidneys, especially over the long term. Both anabolic steroids and diuretics are banned by WADA and the athletic commissions that regulate MMA in the US.
Kidney failure caused by dehydration is treated by giving intravenous fluids. Sometimes this will be enough to allow the kidneys to recover; but at other times dialysis may also be needed.
If this happens severely or repeatedly some people will go on to have chronic kidney disease. In mild to moderate cases, the kidneys can adapt so there may not be any noticeable symptoms. Severe cases may eventually need long term dialysis or a kidney transplant. There’s no such thing as “safe” dehydration. However, people with existing kidney disorders may be at even greater risk. If you have had problems with your kidneys in the past, or you are in a high risk group for developing kidney disease (for example, diabetics) then you should speak to your doctor before competing in MMA, and especially before attempting to cut weight.
Weight-cutting, when done badly, can be one of the most dangerous aspects of MMA. Fighters should make sure that they understand the process and the risks involved.