Hydrating the right way before a workout helps your muscles operate at prime condition.

“When your body is dehydrated, you don’t have the proper muscle power, accuracy, and balance you need to complete a decent workout,” says Angela Onsgard, R.D., resident nutritionist at Miraval Resort & Spa in Tucson, Arizona.

But what you put in your body pre-workout definitely matters. According to Columbia University, you’re supposed to drink 20 ounces of water two hours before a workout, another eight ounces during warm-up, and an additional eight ounces every 10 to 20 minutes depending on the amount of sweat you’re producing.

That’s a lot of liquid—so let’s make sure you’re sipping the right stuff.

Here what you should never chug before a workout.

 MILK-BASED ENERGY DRINKS

Save any drinks with dairy for after the workout.

“Dairy-containing beverages are better to consume post-workout as opposed to before or during,” says Onsgard.

Since milk contains protein, carbohydrates, and fat, it takes a lot of time to digest, she says.

Instead, try whey protein packets mixed with filtered water. You’ll get the benefits of the protein, minus the fat and longer digestion time you’d get with dairy.

SUGARY FRUIT DRINKS

As a kid, you might have loved those squeezable Capri Sun packs, but they’re just not the best choice to drink before your workout.

“Most of these fruity drinks are loaded with high-fructose corn syrup (HFCS), a manmade sweetener that’s been shown to initiate liver dysfunction, metabolic syndrome, and obesity,” says Onsgard.

Instead, add some flavor to your water with fresh citrus fruits, berries, mint, or basil.

“Or opt for coconut water, which replenishes the electrolytes you’ll lose during your workout,” Onsgard says.

BOOZE

This one might sound like a given—but even sipping a beer hours before you go to the gym can mess up your workout.

“Alcohol is dehydrating, inflammatory, and negatively impacts balance and decision-making,” says Onsgard.

Not ideal when you’re trying to decide how much weight to lift.

“If you need a pick-me-up, have some coffee of the dark roast variety (which has less caffeine than lighter roasts),” Onsgard says. “[It] can increase alertness and improve exercise performance.”

CARBONATED BEVERAGES

Fizzy drinks, like soda and seltzer, can cause bloating, abdominal pain, and gas.

They also contain significant amounts of sodium, which draws water out of the body’s cells and can cause dehydration.

If you’re a diet soda fiend, know that most brands contain aspartame, an artificial sweetener that’s been linked to a number of side effects such as migraines, dizziness, memory loss, and mood swings.

“Instead of soda, go for an iced-cold green tea drink,” says Onsgard. “It’s naturally high in antioxidants and is shown to reduce the risk of several types of cancer.”

SPORTS DRINKS

Most sports drinks on the market are actually loaded with sugar  and contain little-to-no nutrition.

“You might get some added vitamins and electrolytes from some brands on the market, but the high sugar content goes right through your system to cause an energy crash later on,” says Onsgard.

“It can wreak havoc on your hormonal system and is a strain for your body to process, on top of the repairing requirements that follow a workout.”

Instead, gulp down some additive-free tomato juice, which provides potassium, has natural sugars, and promotes healthy blood pressure.

The article 5 Things to NEVER Drink Before a Workout originally ran on WomensHealthMag.com.