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10 Nutrition Mistakes That Undermine Workout Results

author image Linda Melone
Linda Melone is a seasoned writer and certified strength and conditioning specialist specializing in fitness and health. She also holds a B.S. in nutrition. Her work appears on WebMD, MSN Health,, AARP, Oxygen and in many other online and print publications.

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10 Nutrition Mistakes That Undermine Workout Results
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You pump, lift, push, pull and sweat, but you’re just not seeing the results from your workout that you’d like. The problem may not be your workout -- it could be your diet. “Most experts say that diet is approximately 70 percent of the weight-loss equation and exercise is the other 30 percent,” says Amy Goodson, M.S., RD, Dallas Cowboys sports dietitian and co-author of “Swim, Bike, Run, Eat: The Complete Guide to Fueling Your Triathlon.” “If you don’t tweak your eating habits with your workout program, you are likely to not see results -- or at least not see them quickly.” A poor diet can also make you tire out faster and increase the chances that you’ll burn lean muscle mass as energy, which can slow your metabolism. Here are the 10 most common dietary mistakes and what you can do to keep from making them.

MISTAKE #1: Working Out on an Empty Stomach
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It may sound like an easy way to save calories and maybe even burn more fat when you exercise on an empty stomach, but it could backfire on you, says Amy Goodson, M.S., RD, Dallas Cowboys sports dietitian. “It’s like going on a trip without putting gas in your car. Having a pre-workout snack provides fuel for your activity and should improve how you feel during your workout.” If you work out in the morning, eating even a small snack will give you the energy to make it through your workout. Examples of good choices include a carbohydrate and lean protein like an apple and peanut butter, Greek yogurt with berries and honey or a protein bar. “These will give you the energy you need to plow through your workout without feeling tired or deprived,” adds Goodson. It’s also important to find something that your body (i.e., stomach) can tolerate during exercise.

MISTAKE #2: Not Drinking Enough Fluids Before a Workout
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If you feel weak after a hard, sweaty workout, it may be at least partly due to dehydration, says Amy Goodson, M.S., RD, Dallas Cowboys sports dietitian. “Many people don’t realize that just a two percent level of dehydration in the body equates to about a 10 percent decrease in performance, which worsens as dehydration worsens.” Dehydration may not only make you feel fatigued, but it can cause headaches and contribute to cramping. Drink water or low-calorie fluids throughout the day, and include 16 to 20 ounces with your pre-workout meal two to four hours before. Goodson recommends following that with five to 10 ounces within 30 minutes of the start of your workout. Continue to drink that amount every 15 to 20 minutes during your workout. “If you are a heavy sweater, you might need to drink on the higher end of the recommendation to stay hydrated and help prevent a decrease in performance,” adds Goodson.

Related: Download LIVESTRONG.COM’s FREE Water-Tracking App

MISTAKE #3: Eating a High-Fat Meal Before a Workout
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If you grab a burger and fries before your workout you’ll likely soon regret it. “It takes a long time for fat to empty from your stomach and digest,” says Susan Kleiner, Ph.D., RD. “This may cause stomach upset when eaten too close to a training session.” Instead, Kleiner recommends sticking to carbohydrates and a little protein and eating a mini meal 60 to 90 minutes before exercising. For muscle building, meals should contain about 50 grams of carbohydrates (200 calories) and 20 grams of protein (80 calories). Kleiner suggests cutting these amounts in half if your goal is to burn fat.

Related: 18 Fat-Rich Foods That Are Good for You

MISTAKE #4: Drinking Only Water During Long Endurance-Exercise Sessions
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If you work out for an hour or less, water should be all your body needs. But longer and more extreme training sessions require additional nutrition, says Amy Goodson, M.S., RD, Dallas Cowboys sports dietitian. “Many people are putting in hours at the gym in addition to training for events like marathons, triathlons and half and full Ironman races. If you are training for two, three and four hours, you will need to add carbohydrates to the mix.” Sports drinks contain carbohydrates in addition to electrolytes to help you replace what you sweat out. If you’re training for a couple of hours at a time, it’s a good idea to take in 30 to 60 grams of carbohydrates per hour. “Sports drinks work well because they not only contribute carbs, but also provide hydration,” says Goodson.

MISTAKE #5: Eating High-Fiber Foods Before Training
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Even if you skip the burger and fries and opt for a big salad, all that fiber could still be problematic before a workout. Fiber also slows stomach emptying and digestion and can cause gastrointestinal distress during exercise, says Susan Kleiner, Ph.D., RD. “Pre-game and pre-exercise meals are not the time to get your fiber. Focus your fiber intake at other times during the day, but not before exercise.” In general, however, fiber works effectively to not only help your digestive system to function efficiently, but can also help you lose weight. Kleiner recommends adding five grams of fiber to your diet a day, which is shown to reduce the risk of becoming overweight by 11 percent. This works best with insoluble fiber found in fruit, dried fruit, nuts and seeds.

Related: 19 High-Fiber Foods -- Some May Surprise You

MISTAKE #6: Running Low on Sodium
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If you sweat profusely and leave sweat stains that show up with white lines in them you’re a “salty sweater,” says Amy Goodson, M.S., RD, Dallas Cowboys sports dietitian. “A diet too high in sodium is typically the problem for most people. However, if you are a heavy exerciser, salt is actually your friend.” When you sweat, you lose fluid along with the electrolytes sodium and potassium. If you do not replace those electrolytes, you run the risk of developing muscle cramps. In addition to consuming sport drinks that contain electrolytes, Goodson recommends snacking on salty foods like pretzels, whole-wheat crackers, beef or turkey jerky, tomato sauce and soups and even salting your food to contribute to your extra sodium needs.

MISTAKE #7: Skipping Nutrition After a Workout
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In addition to eating before your workout, what you chomp on afterward can also determine whether you’re likely to lose weight, gain muscle or do the opposite. “Many people skip recovery nutrition thinking they will burn more calories and lose weight more easily, but the opposite is true,” says Susan Kleiner, Ph.D., RD, USANA nutritionist and author of “Power Eating.” In fact, the proper post-workout nutrition raises your metabolism and calorie burn, slows muscle-protein breakdown and increases muscle building, so your sculpting efforts are improved, says Kleiner. Increased blood flow to the muscles after a workout enables them to quickly absorb glucose (blood sugar). Therefore, it’s best to take in some carbohydrates along with protein immediately after your workout. Examples of healthy carbs include fruit, veggies, sweet potato, quinoa and brown rice or whole-grain crackers. Combine with egg whites, yogurt, lean meat or fish. Or whip up a whey protein shake with fruit and nonfat milk and/or orange juice, depending on your calorie and energy needs.

Related: 8 Things to Consider When Choosing a Protein Powder -- and Our Top 5 Picks

MISTAKE #8: Not Eating Enough
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Your metabolism suffers if you don’t take in enough calories to meet the needs of your activity. “With weight loss and getting lean, most people think less is always better when it comes to eating, but nothing can be further from the truth,” says Amy Goodson, M.S., RD, Dallas Cowboys sports dietitian. Think of your metabolism like a fire: In order for a fire to burn, you have to add wood. If you lack wood, the fire dies. Same thing with your metabolism.” Stoking your metabolism throughout the day involves eating nutrient-rich food consistently. If you don’t, your metabolism will eventually slow down, says Goodson. In addition, consuming too few calories will likely make you feel pretty poorly during a workout. Without adequate fuel, you are typically slower in your cardio and cannot lift as much weight and are less likely to see results.

MISTAKE #9: Not Taking Nutritional Supplements When Warranted
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While it’s a good idea to focus on food first, busy, active and athletic people can find it difficult to plan for enough food throughout the day, especially if they train hard, says Susan Kleiner, Ph.D., RD. “Carbohydrate and protein supplements play an important role for convenience to have the right nutrients available at the right times to support nutritional and performance needs.” Be open to health supplements like multivitamins and minerals, fish oil, vitamin D and probiotics, which are all important to ensure foundational health when energy needs are high, says Kleiner, “and it is difficult to consume the volume of food needed for optimal health.”

Related: 43 Supplements Exposed

MISTAKE #10: Skimping on Protein
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Protein plays an important role in muscle building and fat burning, making it an essential part of your diet, whether you’re trying to gain muscle or lose weight. Protein’s thermogenic effect (the number of calories it takes to digest, absorb and use) is 20 to 30 percent, versus only 3 to 12 percent for carbohydrates, says Susan Kleiner, Ph.D., RD. “This basically means it takes many more calories to digest and use protein than it does carbohydrates. When you include protein in every meal and snack all day long you raise your fat-burning potential.” It’s also more satiating. The best choices for lean protein include eggs, chicken, turkey, fish, lean red meat, low-fat or nonfat dairy (such as Greek yogurt) and vegetable protein. When you crave a high-fat or high-carbohydrate snack, Kleiner suggests reaching for a protein shake instead to keep fat burning and muscle building at peak efficiency.

What Do YOU Think?
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Do you make any of these mistakes? What changes could you benefit from? What changes will you make? What are your favorite foods before and after your workout? Let us know in the comment section below.

Related: 14 Protein-Packed Breakfasts

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