Too Much Water? Yes, It’s Possible and It Can Lead to Sodium Deficiency

Why endurance athletes need to monitor their water intake

By Roberta H. Anding, MS, Baylor College of Medicine and Texas Children’s Hospital
Edited by Kate Findley and proofread by Angela Shoemaker, Wondrium Daily

While the typical American consumes too much sodium and not enough water, it’s possible to swing too far in the other direction. Professor Anding explains.

Male athlete tired on the track
After several hours of high-intensity running, athletes can be in danger of developing hyponatremia from excessive intake of water that reduced their sodium level. Photo By Flamingo Images / Shutterstock

Sodium Deficiency for Athletes

Serious athletes are at particularly high risk for sodium deficiency. Sodium losses are the highest for football players and can range up to 25 grams of sodium, or 2,500 milligram (mg) per liter, of sweat.

Football players must wear helmets and pads, which are for protection, but they don’t adequately allow the body to cool. When the body doesn’t cool, its only defense mechanism is to produce more sweat.

Additionally, the sweat tends to be saltier in the earlier stages of training. An adaption of the body is that the more you train, your body, in its infinite wisdom, then reduces the amount of sodium lost in sweat. If an athlete is acclimatized to the heat, or they’re in shape, they’re going to have less sodium lost in their sweat. 

Athletes or individuals working out for more than an hour are encouraged to drink a sports drink to replace the sodium lost in sweat—something like GATORADE® or POWERADE®, with enough sodium—at least 100 mg per eight ounces—while exercising. Although fluid consumption is important for the prevention of cramping during exercise, it is almost always the excessive loss of sodium or salt that causes cramping. 

Cramping and Sodium

“I have the very fortunate job of working for the Houston Texans, and again, I live in South Texas; there’s a lot of heat and humidity,” Professor Anding said. “I had an athlete who had cramped his whole athletic career.”

This athlete experienced cramping within 20 or 30 minutes of going out on the football field. His sodium losses were significant, and the solution for his pre-game meal was V8® juice—relatively high in sodium—along with a breakfast cereal that had a lot of sodium in it. Ultimately, though, what turned the corner is he had to salt his ham. 

“He didn’t like any of the foods that I recommended, but he was very agreeable to do this because he just had abnormal sodium losses,” Professor Anding said.

The average person sitting at a desk may lose as little as 100 mg of sodium in their sweat a day. Athletic people can often lose excessive amounts of sodium in their sweat.


Your body works hard to keep the amount of sodium and potassium in your blood normal, but sodium deficiencies can occur. The name of a sodium deficiency is hyponatremia: “hypo” means low and “natremia” refers to sodium content in the blood. 

Hyponatremia is most often seen in endurance athletes who eat a large amount of fresh food, eat a diet with very low sodium content, and drink water excessively during exercise. Even the excessive drinking of a sports drink can cause hyponatremia because it’s too much volume of fluid; so, one of the challenges is to get endurance athletes to back off on the fluid, particularly if they’re relatively slow runners.

Say, for example, you’re going to run your first marathon, which you’ve anticipated to be four to five hours. You may not want to drink at every aid station because you could actually overdrink. 

This condition of hyponatremia can cause the brain to swell. It’s characterized by lethargy, lack of energy or enthusiasm, and confusion. In fact, there have been reports of college fraternities hazing with water because people react as if they’d had too much alcohol. Muscle twitching, seizures, coma, and eventually death can occur with hyponatremia. 

“One of the guys that I work with is a medical director for the Houston marathon,” Professor Anding said. “The first year of the Houston marathon, we actually had to admit four women for hyponatremia. They overdrank on the course.”

Risk Factors

One of the main risk factors for hyponatremia in endurance athletes is being female. Often, women avoid sports drinks because they believe these drinks are unhealthy, and they drink a lot of water because they don’t want to get dehydrated. 

While this might seem like a good plan on the surface, overconsumption of water can lead to deficiency because water doesn’t have natural sodium in it. The overuse of non-steroidal anti-inflammatory drugs through some complex physiology can also increase your risk of hyponatremia.

Professor Anding recommends that you calculate your fluid losses during exercise. If you’re running a marathon, you should lose weight. A marathon is over 26 miles, and for every mile you run, you burn about 100 calories, so you should lose some actual body weight in a marathon. 

Before running a marathon, if you are weighing in at 120 pounds and you’re ending the marathon at 120 pounds, chances are that you overdrank. The worst case scenario is that you start out at 120 pounds and finish the marathon at 125 pounds. In this case, you run a strong risk of becoming hyponatremic due to excess water intake.

While it’s important to avoid sodium deficiency, many Americans are at risk for excess sodium, as you’ll learn in tomorrow’s article.

This article was edited by Kate Findley, Writer for Wondrium Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for Wondrium Daily.

Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Children’s Hospital. She also teaches and lectures in the Baylor College of Medicine’s Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.