The idea that athletes need to consume super carb/sodium heavy drinks is not supported throughout the board. We spoke with exercise scientists and medical professionals to find out if sports drinks ever really make sense or if they’re nothing more than overly flavored H20.

What are Electrolytes? Why are Sports drinks so packed-full of them?

“Roughly, electrolytes keep our system functioning,” Barry Popkin, Ph.D., a food science researcher and professor of nutrition at UNC-Chapel Hill. Electrolytes are minerals that are in our blood as well as other body fluids. They consist of primarily sodium, phosphates, chlorine, potassium, calcium, and magnesium. Most major organs help regulate our electrolyte levels, and when they’re correctly balanced, our blood chemistry runs efficiently.

We can often lose too many electrolytes, and we do need to replenish them. But this usually only happens in cases of serious dehydration caused by an illness. Most of our minerals are in our bodily fluids, so if we lose a large amount of any fluid our electrolyte levels will, in turn, drop. You can also lose electrolytes when you sweat, along with water.

Lack of electrolytes can cause headaches and cramping, among many other symptoms. This is because other electrolytes and sodium are crucial when it comes to the electrical impulses that regulate muscle and nerve function. “Not getting enough sodium in fluid replacement can lead to complications like heat cramps, heat illness, and decreased performance,” Mary Jane Detroyer, a registered dietitian, exercise physiologist, and personal trainer. At its most extreme, dehydration can lead to seizures or hypovolemic shock, a drop in blood pressure that decreases the body’s oxygen, which can be fatal.

Everyone is different, and everyone needs different amounts of fluid and electrolytes daily.

Your weight, level of fitness, the environment and many other factors play a large role. “Our fluid and electrolyte losses really depend on our individual bodies, as well as the conditions we work out in,”Ron Maughan, Ph.D., emeritus professor of sport and exercise nutrition at Loughborough University in the U.K.

When perfomring light exercise in a cool, dry environment we are likely to only lose about 250ml of fluid per hour. However, if we exercise in a humid and very hot environment, we can lose 2-3 liters per hour, says Detroyer.

Hyponatremia is a condition that occurs when your sodium concentration is too low, either because you’re not getting enough sodium or you’re drinking too much water.

Hyponatremia happens when your sodium concentration drops below 135 mEq/L. It can be caused by not drinking enough and/or letting your sodium concentration get too low. Over hydrating can be bad too, all of the water dilutes the sodium concentration in your bloodstream.. Most people aren’t measuring how much fluid and sodium you’re ingesting, or how much you’re losing from a workout. The best way to know is by watching out for the symptoms.

However, the symptoms of Hyponatremia can look a lot like those of dehydration—nausea, confusion, and irritability—which can lead to inappropriate treatment. At its most severe, hyponatremia can cause the brain to swell and it can be fatal.

You’re more likely to become dehydrated than overhydrated, so a good rule of thumb is to drink when you’re thirsty and don’t force yourself to chug water if you’re not.

Experts can agree, for most people, drinking water to rehydrate is sustainable. However endurance athletes may need an extra boost.

“If you go to the gym, do 60 minutes of activity, and you’re not a heavy sweater, you don’t need anything more than water,” Detroyer says. A sports drink will just adds calories and sugar that you don’t need.

When you’re exercising intensely for more than an hour, or if it’s really hot out and you’re drowning in your own sweat, you’re most likely losing a lot more fluids and electrolytes than you would in a standard visit to the gym. Most experts recommend replenishing fluids and electrolytes (sodium, specifically) throughout your workout routine. If you are indeed a heavy sweater, or even if you have low blood pressure, Destroyer recommends adding soups and bone broths into your diet. Both have hydrating qualities and are rich in sodium

“When sweat losses are high and recovery time is short, it may be better to have a strategy in place to ensure adequate recovery,” Maughan says. “This means ensuring adequate intake of both water and salt, and letting the kidneys get rid of the excess. Sports drinks may be a convenient option, but the salt content is generally less than optimal: An Oral Rehydration Solution intended for treating diarrhea in children may be a better option.” More realistically, a snack or meal that has some sodium in it should do the trick.

There are many factors that can contribute to how much water/sodium/electrolytes you actually need. The best thing you can do is to just listen to your body. If you are still confused visit a dietitian. Make sure to feel fully hydrated before going to the gym, and to drink when you are thirsty during and post. If you’re sweating excessively, working out for more than an hour straight, or exercising in really hot and humid temperatures, eat or drink something with sodium to keep your electrolyte levels healthy.