When you are not adequately hydrated, workouts can feel more painful. Angela Onsgard, RD, resident nutritionist at Miraval Resort & Spa in Tucson, AZ, states, “When your body is dehydrated, you don’t have the proper muscle power, accuracy, and balance you need to complete a decent workout.”

What you put into your body right before working out can make a different. Research has shown that you should drink about 20 ounces of water about 2 hours before working out, another 8 ounces while warming up, and an additional 8 ounces every 10-20 minutes, but this will vary depending on how much you are sweating. This adds up to quite a bit of liquid, so you should make sure that you are taking in the right fluids.

Here are 5 examples of things you should not drink just before working out.

1. Milk-Based Energy Drinks

Because milk contains protein, carbohydrates, and fat, it can take a while to digest properly. Onsgard explains, “Dairy-containing beverages are better to consume post-workout as opposed to before or during.” You can opt to mix whey protein packets with water, which will give you the protein benefit without the fat and extended digestion time that dairy gives you.

2. Sugary Drinks

Juice boxes, in particular, are a bad choice for a drink just before you are working out. Onsgard states, “Most of these fruity drinks are loaded with high fructose corn syrup, a manmade sweetener that’s been shown to initiate liver dysfunction, metabolic syndrome, and obesity.” Onsgard suggests trying fresh citrus fruits or berries added to your water, “Or opt for coconut water, which replenishes the electrolytes you’ll lose during your workout.”

3. Alcohol

This should be pretty obvious, and most people probably don’t throw back a few beers before working out. Onsgard says, “Alcohol is dehydrating, inflammatory, and negatively impacts balance and decision –making.” This can make certain workouts more dangerous, like weight lifting. Instead, try having a cup of coffee if you need a pick-me-up, which will help you be more alert while working out. Choose darker roasts for lower caffeine levels.

4. Carbonated Drinks

Your body works hard to digest carbonated beverages. They also contain high levels of sodium, which can be dehydrating. The artificial sweeteners, like aspartame, may also cause unpleasant side effects, including migraines, dizziness, memory loss, and mood swings. Onsgard recommends, “Instead of soda, go for an iced green tea drink. It’s naturally high in antioxidants and is shown to reduce the risk of several types of cancer.”

5. Sports Drinks

Most of the sports drinks on the market have tons of added sugars and little nutritional value. Onsgard expands, “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. 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.” Opt for all-natural tomato juice, which gives you tons of potassium, natural sugars, and helps promote healthy blood pressure.

When you are getting ready for your workout, make sure you are fuelling your body with what will work best to get the results you want!