Osmo is a hydration drink developed by nutrition scientist Dr Stacy Sims. It's designed to optimise fluid intake, delay fatigue, boost endurance, reduce cramping and maximise cardiovascular efficiency.
Osmo says the drink can do all this through a formula that promotes gastric emptying. Despite that term sounding foreboding, it’s actually a good thing – it refers to the body’s ability to move fluid from the stomach to intestines for absorption into the blood. The fluid is then available for use in thermoregulation through sweating, respiration and circulation. The drink is available in orange and blackcurrant (we tested both) and there’s also a full women’s range that’s tailored for optimum performance throughout the menstrual cycle.
Key to the formula is that the drink’s combination of glucose, sucrose and sodium citrate are of the right concentration to speed fluid absorption due to the drink having a lower osmolality (the amount of solutes in a solution) than blood. Osmo also says the sodium citrate also creates electrolyte balance that wards off cramping.
Despite the importance of the ingredients in Osmo, the concentration of the drink doesn’t have to be exact. Dr Sims suggests two scoops of powder for 500-750ml and recommends going light rather than heavy when mixing.
According to Osmo, the high carbs of most energy drinks put them outside the optimal osmolality range, reducing their ability to hydrate properly and increasing gastrointestinal distress.
While this reviewer hasn’t ever suffered from race-ending tummy troubles, switching from a high-carb solution to Osmo has resulted in noticeable positive changes. Whereas previously a few hours of swigging energy drinks would create a sickly sensation in the pit of the stomach, Osmo caused no such issues – though we didn’t see a drastic change in level of cramping (cramps are mercifully rare anyway).
It certainly takes a few weeks to get used to Osmo, not just because of its rather bland, slightly salty taste (which actually becomes light and refreshing given time adapting to the flavour) but because it’s primarily a hydration drink. There are only 9g of carbs and 35 calories per serving, meaning those who are reliant on carb intake from energy drinks will need to rethink their nutrition strategy and eat more to offset the difference.
You do need to be vigilant about food intervals during rides without extra carbs being only a slurp away, but in the six months we’ve been testing Osmo this approach has led to a more settled stomach – allowing us to eat more, fewer peaks and troughs in energy levels and no issues with dehydration. By extension, fatigue was kept at bay – enabling us to ride comfortably for longer.