You're Not Drinking Enough Water
"The human body is roughly 60 percent water, and keeping it well hydrated helps it function properly," says Pamela Nisevich Bede, M.S., R.D., a sports nutritionist at Abbott. "While it may seem like a no-brainer that you'll want to hydrate after training, it's essential to keep your hydration levels steady throughout the day."
What's more, that feeling of thirst could be mistaken for hunger and lead to overeating, she says. And, if you're training for a marathon, you might be hungrier than usual, says Michael Jonesco, D.O., a specialist in orthopedics and sports medicine at The Ohio State University Wexner Medical Center. Leptin, a hormone that has been said to stifle appetite, is suppressed for the rest of the day following a morning jog, which may contribute to intense hunger felt by many runners throughout the day, he says. (Learn more about leptin resistance. It could be the answer to why you're always hungry.)
Here's how to make sure you're drinking enough: On average, women need 91 ounces (11.4 glasses, or 2.7 liters) of water each day, and men need 125 ounces (15.6 glasses, or 3.7 liters), according to the Institute of Medicine. "You can replace a few glasses with fruits, juices, vegetables, and even coffee," says Bede.