On Nutrition

Let’s face it, higher summer temperatures mean we sweat more, especially when exercising outdoors. While you probably know that you need to replenish fluids lost from sweat, you might wonder if your body needs something more robust than water. For general hydration needs, including after low-intensity or brief bouts of exercise, plain water is sufficient. But when exercising at moderate or vigorous intensities and longer durations — 45 minutes is a typical guideline — especially in hot or dry weather, it’s also important to replace carbohydrates and electrolytes.

Every cell in your body contains water, which demonstrates how important it is. Electrolytes, minerals in our blood, sweat and urine, are also important. They include sodium, potassium, chloride, calcium and magnesium and are essential for proper nerve and muscle function — including our heart muscle. They are also key to proper hydration for a really specific reason — they maintain proper fluid balance inside and outside of our cells. Severe dehydration can cause electrolyte imbalances because you lose water and electrolytes, especially sodium, when you sweat.

If you’re a serious recreational exerciser or if you train for sports events, you’ve probably already established a fueling and hydration plan that works for you. However, if you’ve upped your physical activity this summer and need to do more than drink enough water, you have a lot of options. Electrolytes are found in many foods — including fruits, vegetables, dairy, nuts and seeds — so you could stick to water and augment with fruit and something containing salt. You could also go straight into your next meal if it’s time and you’re hungry.

What about sports beverages such as Gatorade or Powerade? These certainly provide fluids along with electrolytes and carbohydrates in the form of sugar. But many of these beverages contain what is arguably an excessive amount of sugar. Some brands have artificially sweetened sugar-free versions, but what if you could actually use some carbohydrates to refuel?

A 2016 study in The American Journal of Clinical Nutrition found that milk may keep your body hydrated longer than simple water. Why? Because along with water you also get the natural sugar lactose, plus some protein, fat, sodium and potassium. When compared with a broad range of beverages, whole and skim milk hydrated better than all contenders except for oral rehydration solution (think Pedialyte), which are used to treat dehydration, not for post-exercise hydration.

Of course, milk isn’t an option for everyone. You might not like it, you might choose to not eat dairy foods, or you might find that milk doesn’t agree with your digestive system. So you might be interested to know that orange juice came in closely behind milk in this study, and a separate 2020 study in the Journal of Nutrition and Health Sciences found that, thanks to its water, carbohydrate and electrolyte contents, orange juice functions well as an alternative post-exercise rehydration beverage.

The study looked at whether orange juice might cause digestive distress after exercise — due to its acidity and its higher carbohydrate content — when compared with water and commercially available sports beverages. Not only were the orange juice drinkers in the study not more likely to experience digestive distress, but (fun fact) orange juice is less acidic than sports beverages. When choosing orange juice, be sure to go for 100% orange juice, not an “orange drink” or “orange-flavored” beverage, as those may contain little actual juice.