"I always recommend consuming at least 15 to 30 grams of carbohydrates before a very early training session," Ansari says. "If you can't eat a meal, grab a snack with these guidelines (bananas, bars, fruit pouches, dried fruit, electrolyte-enhanced beverages). If you have enough time before the workout, I would aim to eat a full meal, as this will help to keep energy stable for a longer period of time. By not eating, you're putting yourself at risk of not being able to have enough energy to get the most out of your high-intensity workouts! You want to be able to fuel enough to put enough energy toward a training session."
Foroutan adds that you should listen to your body when it comes to making this call. "As long as you don't feel compromised in your workout—like you're not feeling dizzy, you're not feeling weak—then it is perfectly safe," she explains. "Because when you really think about it, our bodies are designed to tap into stored energy when we haven't eaten in a while."
But if you do forgo a snack or meal, Rueven says you should plan on eating something within 30 to 45 minutes of working out that contains both protein and carbohydrates to replenish glycogen stores and support muscle repair. And for early workouts, Ansari says you can prep the night before by making sure your dinner helps support morning training.