Whether you want to ramp up your one-rep maxes, put on muscle mass, lose weight, or run faster, what you eat is just as important than what you do in training. Food is, after all, the fuel your body uses to keep you going throughout your workouts, as well as the first aid kit that repairs your muscles afterward, explains sports dietitian Emily Fultz, M.S., R.D., L.D.N., of Fit with Food. “You can work out all you want, but if you’re not fueling adequately for your fitness goal, then you won’t achieve it or reach your highest performance potential,” she says. In fact, it’s all too common that misguided nutrition, not training gaffes, undermine progress.
Ahead, sports dietitians break down seven of the most common mistakes people make in the kitchen that sabotage all their hard work in the gym.
1. You Go Light On Carbs But Heavy On HIIT
Low-carb diets had a moment in the 1990s and then enjoyed a resurgence a few years ago when keto was all the craze. While low-carb diets may benefit people who want to lose weight, experts recommend against them for serious athletes, as well as those who frequent bootcamp classes or do other HIIT-style training.
“Carbohydrates are your body’s main source of fuel, in particular during high-intensity exercise,” says sports dietitian Amy Goodson, M.S., R.D., C.S.S.D., L.D., author of The Sports Nutrition Playbook. Choose not to eat them, and likely you’ll be too fatigued during your workout to go as long or as hard as you would like.
Read More: 7 Signs Low-Carb Isn’t Working For You
Exactly how many carbohydrates an individual should consume each day will vary based on factors like how they’re exercising, body weight, and personal body chemistry. That said, the Dietary Guidelines for Americans recommend that 45 to 65 percent of an individual’s total daily calories come from carbohydrates. For an individual consuming 2,000 calories per day, that’s between 900 and 1,300 calories (which is 225 to 325 grams) from carbs.
More important than consuming enough carbohydrates, however, is consuming the right type of carbohydrates. “The majority of Americans are filling up on highly-processed, simple carbohydrates like chips, cookies, and crackers that contain a lot of sugar and are not filling,” says Goodson. Generally, healthier and more satiating are complex carbohydrates, like whole-grain bread, oatmeal, and quinoa, she says. As an added bonus, most complex carbohydrates will inch you closer to your daily fiber intake goal, which supports gut and heart health, she says.
2. Your Calorie Intake Overpowers Your Energy Burned
While different fitness goals require different nutrition protocols, “it’s common for people to out-eat their exercise routines,” says Goodson. In other words, many people eat more calories overall than their body needs or than their workouts require.
Consider the person who goes on a hearty hour-long run: “Sixty minutes on the treadmill burns approximately 600 calories,” says Goodson. If that runner heads to dinner with their friends post-workout, they’ll consume the same number of calories after two glasses of wine and some table munchies, she suggests.
“Many people think if they exercised that day, that affords them the opportunity to eat more, but this usually isn’t the case,” says Goodson. This is particularly important to be wary of if losing weight or reducing body fat is the goal. “In order to lean out or lose weight or body fat, there has to be a deficit of calories, which means you have to be careful that you are not eating back all the calories you burned off in exercise.”
Of course, a variety of other factors can contribute to overeating. For example, falling short on your protein goals and consuming mostly processed (read: quick-digesting) carbohydrates can leave people hungry, regardless of how many calories they’ve eaten, says Dr. Chris Mohr, Ph.D., R.D. “Protein helps fill you up, and data shows you’ll eat less overall when you consistently eat protein, aiming for about 20 to 30 grams a few times throughout the day,” he says. (A protein powder supplement can help you get there.)
To have your calorie and macronutrient intake in balance with your training routine, you’ll first want to learn how many calories and grams of each macronutrient you need based on your current activity level and goals. Plugging your information into a nutrition and fitness tracker like MyFitnessPal or the Mayo Clinic calorie counter can help you figure that out. From there, Goodson recommends tracking your intake for a few days to see where you are and what adjustments you might need to make.
3. You Don’t Eat Enough Calories To Fuel Your Workouts
Sure, eating too many calories can interfere with your fitness goals, but so can eating too few. “Calories to your body are like gas to a car; they fuel it,” says Goodson. Consuming too little fuel can make your body think you’re entering a famine. Ultimately, this makes your body hold on to body fat as well as slow your metabolism down so that you burn fewer calories, she explains. In serious cases of under-eating, your body even starts to break existing muscle mass down for energy, adds Fultz. No matter what your fitness goal is, under-fueling sabotages it.
“Another thing to note is that when you eat too little, you likely have less energy, which can impact your performance at the gym,” Goodson says. If you exercise at a lower intensity or lift less weight because of fatigue, it’s likely you won’t burn as many calories or put enough stimulus on your body to support meeting your goals.
In addition to crummy workout performance, loss of motivation and symptoms of depression and anxiety can all also indicate that you’re in desperate need of more adequate fuel.
Your move: Calculate your resting metabolic rate (RMR), which is a measure of the number of calories you burn doing basic human functions like circulating blood, thinking, and moving, says Goodson. “Then, make sure you are eating at least that many calories per day,” she says. Eating less than your RMR can result in relative energy deficiency and result in both health and performance consequences.
4. You Pass On A Pre-Workout Snack
A pre-workout snack supplies your body the energy it needs to maximize performance, says registered dietitian Mallory Aldred, R.D., founder of What Mallory Eats. “If you’re not fueling for your workout, a lack of energy may cause you to back out or not perform to the best of your ability,” she explains. In cases where you’re seriously underfed, forgoing a pre-workout snack can even lead to lightheadedness and dizziness, which guarantee your training session gets cut short.
How much you should eat depends on how much time you have before you work out, says Aldred. But, as a general rule, the International Society of Sports Nutrition suggests aiming for a snack that emphasizes carbohydrates for energy and protein for muscle repair. Oatmeal with protein powder, a hard-boiled egg with crackers, or half a turkey sandwich are all good bets.
“In most cases, you’ll want to wait at least an hour after your snack to hit your cardio or strength-training session so that you feel energized but not overly stuffed,” Aldred adds.
5. You Don’t Refuel After Exercising
While you exercise, two things happen: Your body taps into stores of carbohydrates (glycogen) for energy, and tiny microtears are shorn into the muscles that work past their current capacity, explains Fultz. After exercise, the best thing you can do is replenish those glycogen stores with carbohydrates and help along the repair process by consuming protein. “Fail to eat protein after a workout and you’re essentially hanging out with broken-down muscles all day or night,” she says.
Read More: 5 Post-Workout Snacks Trainers Rely On To Refuel
Whether you opt for a post-workout snack or a full-on meal will depend on the time of day you hit the gym. As a general rule, however, Goodson says you want to try to consume at least 15 to 25 grams of protein and 45 to 75 grams of carbohydrates after exercise. As it goes, the American Council on Exercise recommends consuming the two macronutrients in a one-to-three ratio of protein-to-carbs.
To be clear: Eating after a challenging workout is important even if you do that workout after dinner, says Aldred. Since figuring out how much you can eat between your workout and bed can be tricky (too much food too close to bedtime can disrupt sleep for some people), she recommends giving yourself at least two hours between noshing and napping.
6. You’re In A Perpetually Dehydrated State
This is not a drill: More than 75 percent of people are chronically dehydrated. Typically marked by fatigue, muscle cramps, lightheadedness, and dizziness, chronic dehydration can interfere with your workouts, as well as with your ability to recover from said workouts, according to Goodson.
“The most common side effect of dehydration is fatigue,” she says. “If you try to exercise when you’re dehydrated, you’re going to feel like you’re working harder than usual.” As a result, you’ll burn fewer calories or lift fewer pounds than you would if you have been properly hydrated. Actually, research shows that just a two percent reduction in body weight from dehydration is enough to thwart training.
Read More: The Many Perks Of Staying Hydrated Around The Clock
Your workout performance isn’t the only thing that will take a hit; your recovery will, too. One study out of the Gatorade Sports Science Institute found that dehydration impeded the efficacy and efficiency of muscle repair, which in turn increased muscle soreness.
“The solution is to consume at least 64 ounces of water per day, which should include at least 16 to 20 ounces of fluid in the two hours leading up to a workout, as well as five to10 ounces of fluid every 15 to 20 minutes throughout a workout,” Goodson recommends.
If it’s hot and humid or you’re already experiencing symptoms of dehydration, Goodson suggests adding electrolytes (like sodium and potassium) to your beverage. Hydration supplements like Liquid IV and Biosteel are an easy way to do it.
7. You Go Harder At The Bar Than You Do At The Barbell
Hate to break it to you, but if you have a “work-out-hard, party-hard” mentality, your post-sweat sips could be the culprit behind any slowed progress.
The body sees alcohol the way your friends see your ex: toxic. Since your body identifies alcohol as a toxin, it prioritizes flushing alcohol from the system over other processes, including the muscle repair process, Goodson explains. When alcohol is in your system, muscle recovery takes a backseat, which can intercept your ability to meet your fitness goals.
Not to mention, “alcohol also adds a lot of calories to your daily intake,” notes Goodson. A bottle of beer contains approximately 150 calories, a glass of wine has 110, and some mixed drinks can top 300, she says. To make matters worse, people typically care less about what they eat on nights they’re drinking. “Many nights heavy on alcohol are also heavy on calories from junk food,” she says. If you don’t factor these calories into your total daily consumption, your alcohol (and junk food) intake can quickly eat up any caloric deficit or balance you were hoping to maintain.
On top of all that, even if you muster up the willpower to hit the gym after a wild night, you will likely move slower, burn fewer calories, and generally have a subpar workout. Research, after all, has found that a hangover can reduce exercise performance by more than 11 percent. Bottom line: Partying hard is a surefire way to stall your progress, regardless of what fitness goals you want to achieve.