Carbohydrate usage by endurance athletes has been studied for decades by
independent researchers such as the American College of Sports Medicine
and the results have consistently shown the significant benefits that
are achieved when using primarily complex carbohydrates instead of
simple sugars. To understand why you have to go back to your 10th grade
biology class when you learned about osmosis.
The beauty of a good sports drink is that it is rapidly absorbed in your
small intestine by osmosis without the digestive requirements associated
with fats, fibers and proteins. Another way
of looking at this is that the water in your sports drink becomes the
transport vehicle for the other good stuff in your drink (energy and
electrolytes). However, in order to be absorbed, the fluid in your
intestine has to be an equal or lower concentration than your body
fluids. The measure of fluid concentration is called osmolality.
The osmolality of Osmo is approximately equal to your body fluids (isotonic),
thus allowing it to be rapidly absorbed - that's a good thing. The
beauty of complex carbohydrates is that because of their larger
molecular structure you can get much, much more energy in an isotonic
solution compared to a drink made with simple sugars. Case in point,
e-Fuel is also isotonic but it contains more than twice the energy of Osmo -
that's an even better thing!!
Both drinks will be rapidly absorbed, both will keep you hydrated, both
will replenish your electrolytes ... but e-Fuel will provide twice the
energy. Bottom line, if you're an endurance athlete there isn't
enough energy in Osmo to keep you going, you need to get more
energy from somewhere.
Peer-Reviewed Science ...
Osmo likes to promote the fact that their products are based on
peer-reviewed science, most of which was done by one of the
company's founders (Stacy Sims). According to Osmo, their simple
sugar formula is absorbed faster than other drinks. However,
what's even more valuable (and believable) is independent
research (not performed by or paid for by the company trying
to sell the product).
Fortunately there has been lots of independent work done in this
area, and it has been proven that what determines the absorption
rate is the osmolality of the solution, NOT the carbohydrate
sources. One study for example is "Intestinal water
absorption from select carbohydrate solutions in humans,"
Gisolfi CV1, Summers RW, Schedl HP, Bleiler TL., J Appl Physiol
(1985). 1992 Nov;73(5):2142-50. In this study researchers
concluded that three isotonic solutions consisting of glucose,
sucrose and maltodextrin were all absorbed at the same rate
despite the fact that the maltodextrin solution contained
approximately twice as many calories.
A second reference can be found in "Intestinal fluid
absorption during exercise: role of sport drink osmolality and
[Na+]" by Gisolfi CV, Lambert GP, Summers RW at the
Department of Exercise Science, University of Iowa, published in
Medicine and Science in Sports and Exercise [2001,
33(6):907-915]. In this study, researchers looked at solutions
containing sucrose and glucose (used in Osmo), fructose, and
maltodextrin (used in e-Fuel). The conclusion was that "gastric
emptying was not different among solutions" and "net fluid
absorption was not different among beverages".
So, as we stated above, both Osmo and e-Fuel will be rapidly
absorbed, both will keep you hydrated, both will replenish your
electrolytes ... but e-Fuel will provide twice the energy.
Osmo Recommends That You Drink Your Hydration and Eat Your
The logic is that you want to absorb the drink fast to stay hydrated so
you shouldn't load it with calories. Instead they recommend drinking
Osmo and eating other foods to get your calories. Unfortunately this
logic just doesn't make sense for three reasons:
Problem # 1 - It all
ends up in the same place
Unlike cows that have four stomachs we humans only have one. Once you
start eating and drinking it all ends up in your stomach .... the
Osmo, the banana, the PowerBar and what ever else you decide to eat.
Guess what, the osmolality of the fluid in your stomach just went up and
the absorption rate slowed or even came to a halt. Not a good thing.
Problem #2 - Digestion
Most foods that you eat contain proteins, fats and/or fibers. Once one
or more of these are introduced to your stomach they have to go through
a digestive process. When you are doing aerobic activity the blood
supply to your stomach gets shut down in order to maximize blood flow
(and oxygen) to the working muscles for the oxidation process. More
oxygen = increased performance (just ask Lance). Digestion of those
foods you just ate requires blood flow back to the stomach and away from
the working muscles ... and that sound you just heard was your
Problem #3 - Delayed Energy
We all know that bananas are one of the most common foods consumed by
endurance athletes, but do you know how long it takes a banana to leave
your stomach? Try 4 hours and 15 minutes! Eating solid foods during
typical workouts or competitions might taste good and satisfy your
craving for food, but it does little if anything for your performance.
Note About Ultra Endurance Athletes
If your an ultra athlete competing for 20+ hours the normal rules don't
apply to you. You are going at a slower pace so you can afford some
blood to go back to the stomach to work on digestion. And if it takes 4+
hours for the banana to kick in that's okay!