We’ve all been there: You’re just gearing up to crush a workout, and then it strikes. “It” being the stomach cramping, the bathroom urgency, the wave of fatigue. If you’re exercising outside or in the middle of a fitness class, this gastrointestinal distress can be even more discouraging.
Although a sudden virus might be at play, it’s more likely that what you ate just before working out could be the culprit. “Exercise and digestion are mutually exclusive,” says Shawn Khodadadian, MD, of Manhattan Gastroenterology. “When you exercise, your body isn’t using its energy for digestion. It slows that process so it can divert as much blood as possible to your muscles and lungs.”
That means foods you digest just fine when not working out could cause you problems if you eat them pre-exercise. Certain foods can prompt heartburn, stomach ache or even vomiting, Khodadadian notes.
Here are some common food choices to avoid:
1. PROTEIN SHAKES & BARS
While protein is very helpful for post-workout recovery, it can be tough on your system if you have a shake right before working out. That’s because protein digests slowly, Khodadadian says. If you’re having a shake less than three hours before a workout, you could see some digestive blowback. The same goes for a high-protein bar.
The fix: If you regularly rely on a protein boost right before working out, and tend to feel not-so-great while exercising, try having the shake or bar after exercising instead.
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Many runners love their chocolate milk fix, but they’re careful to drink the beverage after a big run or a race. That’s because milk has high amounts of protein and fat, which take time to digest.
The fix: If you’re looking for a dairy-type boost in your pre-workout mix, consider whey protein mixed with filtered water instead — but even then, consume the drink at least a few hours before your workout.
3. HIGH-FIBER CEREAL
Loading up on a carb-rich choice like cereal is tempting before exercising, especially if you’re pressed for time. But, like protein, fiber digests slowly, and your workout can interfere with that process, Khodadadian notes.
The fix: As an alternative, try a food you can digest easily that’s high in carbs but low in fiber, such as oatmeal. That way, you can get the fuel you need without the GI issues. Consider adding even more of a carb boost with bananas or mangoes.
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4. SPICY FOOD
Even if you regularly amp up your spice levels, you may have issues if you eat too much before working out. The slower digestive processes that happen when you begin exercising could leave that delicious taco sitting in your stomach, and that can prompt indigestion or heartburn.
The fix: Skip the spice altogether and save the heat for a post-workout treat.
Yes, you should load up on vegetables. But eating raw veggies can be tricky, says Terry Wahls, MD, author of “The Wahls Protocol.” Although raw vegetables have more fiber than cooked, they also have intact enzymes and their cell walls are still solid, which means it takes more energy for your body to digest them. If you’re just sitting in an afternoon meeting, that’s no big deal. But if you’re trying out your new HIIT workout, it can become a source of digestive problems.
The fix: Opt for easier-to-digest, lower-fiber cooked vegetables and save the salad for another time.
WHEN SHOULD YOU EAT?
Although some people swear by “fasted cardio” workouts, it’s usually more effective to eat something before exercising, according to Khodadadian. He says, “Not eating anything before a workout will leave you feeling tired and weak. Just give your body the proper time to digest before exercising, you may need two or three hours for digestion.”
Your blood sugar rises to help you digest, he adds. By waiting a few hours, those blood sugar levels will drop back to normal, giving you the energy you need to devote to your workout — without a stomach ache or heartburn along the way.