5 things you should never eat before a workout

It goes without saying that your choice of pre-workout fuel can play a major role in making—or breaking—your performance. (Case in point: There probably aren’t many Olympians eating Big Macs before their main events, even though there’s a McDonald’s in the PyeongChang athletes’ dining hall.)

But surprisingly, it’s not just junk food that should be avoided before you sweat, says Beth Warren, MS, RD, CDN. “Some otherwise healthy foods can linger too long in your stomach,” the nutritionist explains. “That can slow you down, cause gas, and even send you to the restroom mid-workout.”

If you’re squeezing a spin class into your already-packed schedule, there’s a good chance you’ll want to spend every precious minute on the bike, right? To help you get the most out of your workouts, Warren shares five things you should never eat or drink before hitting the gym, no matter how loudly your stomach may be growling. (She suggests having a handful of almonds or a hydrating kale smoothie instead, preferably 30 minutes before your workout.) 

Check out these five foods and drinks that you should save for after your workouts—and prepare to make a few adjustments to your Saturday brunch order.

1. Avocados (and other high-fat foods)

Although half an avocado may seem like a harmless way to curb your hunger pangs, it’s best to avoid this beloved snack before a workout. “Foods with a lot of fat take a long time to digest and remain in the stomach a while, regardless of the source,” explains Warren. “Eating these types of foods will also draw blood into the stomach to aid in digestion, which can lead to discomfort and cramping.” Yes, this includes the healthier kinds of fats—sorry, Bulletproof coffee fans.

If high-fat foods are the only thing available to you before your workout, Warren says to eat them in small doses. “You can opt to have a tablespoon of a healthy fat or a protein-rich food, like natural peanut butter combined with a carbohydrate like an apple, but make sure to keep note of the portion size and see how you feel,” she says.

2. Beans

Save the burrito for your commute home from the gym. Although beans are a protein-packed food with lots of health benefits, they are also loaded with fiber—which is a good thing in general, but can cause digestive distress when you’re breaking a sweat. “A single cup of beans has 16 grams of fiber, which includes the indigestible carbohydrate raffinose,” says Warren. “Eating them and other high-fiber foods can cause bloating and gas if eaten right before a workout.”

And what if hummus or bean dip are the only things in your office fridge—and you don’t have time to pick up another snack before yoga? Warren recommends sticking to just two tablespoons, and leaving at least a half hour between your snack and your workout.

3. Alcohol

Pro-tip: Never schedule a boozy brunch with your girlfriends before your afternoon run. “Alcohol can really dehydrate you and suppress fat oxidation,” says Warren. “This may mess with your fitness goals, even if you drink extra water.” Not to mention that getting a little tipsy can affect your energy levels, concentration, and overall form—all of which can set you up for injury.

4. Dairy

On paper, milk and yogurt sound like perfect pre-workout fuel sources—but there’s a catch. “You’ll get your protein, your carbs and fat, all of which are required by the body during a workout to some extent,” explains Warren. “However, tons of people have trouble digesting milk, which can be a major problem before exercise.”

With that in mind, a latte or parfait may not be your best option before boot camp, unless you want to risk an upset stomach, diarrhea, gas, or bloating. “There are some people who can tolerate milk pretty well, but it’s best to skip it if you are not one of them,” Warren says. “Milk can be a great food choice, but it really depends on the individual.” When in doubt, opt for an alt-milk or non-dairy yogurt instead.

5. Carbonated drinks

Yes, a can of La Croix is a better-for-you alternative to sugary soda. But when it comes to hydrating before a workout, flat water is always your best bet. “Drinking carbonated beverages of any kind can cause gas and bloating while working out,” says Warren. 

To keep your stomach free of air (and prevent your burpees from feeling even more excruciating), add a kick of flavor to your tap water with cucumber or strawberry slices—and think of the kombucha in your fridge as a reward for after your cool-down.

Want to get an extra brain boost with your workout? Science says to drink beet juice an hour before. And if you’re doing Whole30, here’s what one trainer recommends eating before you hit the gym.