Osmolality 101

Osmo-FIT System Badge

More is Not Always Better

Osmolality is used to describe the concentration of particles dissolved in a solute. It is a measure of density and is expressed in units of measurement known as osmoles or milliosmoles (one thousandth of an osmole), per 1000g of solvent, or mosm/kg.

The osmolality of a solution is affected by the nutritional components that go into it. The more particles a rehydration beverage contains (such as carbohydrates, electrolytes, amino acids, vitamins, minerals, protein and flavoring), the higher its osmolality. Osmolality affects the way the solution is digested and utilized as fuel within the body, which means your choice of sports drink can affect your athletic performance.

Optimal absorption of fluids within the body happens when a sports drink solution is equal in terms of osmolality to what naturally occurs in the body. The osmolality of our body's own fluids are approximately 280-300mosm/kg water and are regulated by the intrinsic mechanisms within our own system.

Fluids supplied with osmolality above 300mosm/kg, (i.e. hypertonic solutions), cause not only delays in gastric emptying but also more importantly will cause fluid shifts from the body to the gut before absorption occurs. Such delays in rehydration introduce the real potential to delay and reduce performance. (Alonso, 1998, Hargreaves, 1991, Sowka et al, 2000).

Solutions with an osmolality around 280mOsm/kg are considered isotonic. Those with a lower or higher osmolality are referred to as hypotonic and hypertonic, respectively. Optimal absorption of fluids happens when your sports drink solution is isotonic. Also, isotonic beverages can assist in rapid gastric emptying, which decreases that "sloshing" full feeling and the gastrointestinal distress that often comes as a result.

Solutions, which are marginally hypotonic, (that is are below the osmolality of the body), are known to be emptied quickly from the stomach and have the potential to be absorbed the most rapidly. (Leiper, 1998).

As the osmolality of your sports drink increases above 300 mosmol/kg, efficient uptake from the GI tract decreases and can cause gas, bloating, and cramping. In fact, solutions with high osmolalities (hypertonic) can actually draw fluid out of the body. This delays rehydration, can cause dehydration, and can have serious effects on your performance. For the everyday person, this may not be a problem. But for athletes who demand the most out of their bodies and are turning over large volumes of fluids and electrolytes each day, it could literally mean life or death.


Hypertonic Solution's Effect on the Body


In a hypertonic solution, there is too much “stuff” in your stomach so your stomach pulls in water to dilute it. This pulls valuable water from the working muscles and can cause cramping, nausea, bloating, diarrhea, and gastric distress.




Hypotonic Solution Effects on the Body


In a hypotonic solution, there isn’t enough “stuff” in your stomach – too little sodium, and too much water. In order to digest and absorb what’s
in your fuel, your stomach pulls sodium from the muscles and can lead to cramping, hyponatremia, dehydration, and over-heating.




Isotonic Solution's Effect on the Body



In an isotonic solution, there is just the right amount of “stuff” in your stomach that it matches the osmolality of the body. Electrolytes, carbohydrates, and water head to the muscles, and what is in your stomach is quickly digested. This adequately replaces fluids and electrolytes, provides rapid hydration, and provides energy through carbohydrates.



The Osmo-FIT System
is a patented process that automatically calculates the osmolality of your personal performance sports drink guaranteeing that it will easily digest and give you the results you are looking for come competition time. Learn more about the INFINIT Osmo-FIT System and how it can help your performance.

For more information on the INFINIT Osmo-FIT System, our 100% satisfaction guarantee, or to have one of our experts build an all-in-one Custom isotonic hydration and fuel mix contact us.