Share on Facebook

50 Fitness Myths That Can Seriously Damage Your Health

You've heard these "facts" so many times, you've just accepted them as true. But they're not, and they can sabotage your fitness levels or worse—putting you at risk for a multitude of injuries and health problems. Learn the actual truth here.

Myth: Yoga is so gentle, it won’t cause injuries

Be careful or you might be saying ouch instead of om. Researchers from the University of Sydney found that yoga causes injuries ten times more often than anyone thought: 10 percent of practitioners reported muscle pain; 21 percent of people with existing pain found that yoga made it worse—a rate that matches other sports. Still, yoga has many benefits—from increased flexibility and strength to lower blood pressure—and 74 percent of study participants said their existing pain lessened. To avoid trouble, make sure you’re doing your poses safely, listen to your body, and let your instructor know about any existing injuries or limitations. Read up on the 9 other popular workout moves that could injure you.

Black man doing stretching before running in urban background. Young male exercising listening to music with headphones.UfaBizPhoto/Shutterstock

Myth: Stretching before a workout prevents injuries

Reaching for your toes before a workout—aka static stretching, the stuff we were all taught to do in gym class—can actually cause injury. According to Time, save that type of stretching for after your workout. Before working out, warm up with some light cardio and then do movement-based, dynamic stretches, like arm and leg swings, which properly prime your muscles and will provide the foundation for a better workout.

Female runner running outdoor in nature. Young woman jogging in morning looking over shoulder.Jacob Lund/Shutterstock

Myth: Exercising on an empty stomach first thing in the morning burns fat faster

The theory: If there’s nothing in your stomach, your body will be forced to burn fat for energy. The reality: Your body may turn to muscle for fuel, which, in turn, will give you less energy for your workout and potentially cause dehydration, hyperglycemia, and lightheadedness. Some experts also warn that this approach could actually slow down your metabolism. To optimize your workout, eat a light, easily digestible meal 90 minutes before exercising. Here are 5 other fitness myths that you shouldn’t believe.

Portrait of a handsome bodybuilder doing exercise on fitness machine in gymDean Drobot/Shutterstock

Myth: Machines are safer than free weights

Sure, with a machine, you won’t drop a barbell on your foot (or worse), but you could still hurt yourself. “Machines that restrain the form can lead to chronic pain in the joints,” explains Sebastien Lagree, founder of the Lagree Fitness Method and inventor of the Megaformer and Supra machines. “Make sure that your range of motion is not compromised.” No matter which technique you use, a pro should give you a lesson.  Check out these other common exercise moves that actually work against you.

closeup of a young caucasian man drinking a green detox smoothie served in a glass jar at the officenito/Shutterstock

Myth: A detox will reset your system and help you lose weight

The problem with myths is that they often come with a hint of truth, like this one. After all, you will see some initial weight loss when you forgo solid foods. But, as experts who spoke to Shape explain, a long detox can actually slow down your metabolism and make it harder to maintain any weight loss. Plus, you’ll lose muscle mass and when you inevitably gain some of the weight back, you’ll gain it back as fat. As a result, your body will be less fit and less healthy than it was before you started the detox. Consistent and smart food choices are always the way to go for long-term fitness results.

Businessman Working On Computer In OfficeMonkey Business Images/Shutterstock

Myth: Exercising counteracts the effects of sitting at a desk all day

Believe it or not, if you’re 45 or older, you’re probably sitting for around 12.3 hours of a 16-hour waking day. And that’s a problem, according to a study in the Annals of Internal Medicine, because the more you sit, the higher the likelihood that you’ll die sooner. Researchers found that being sedentary for more than 13 hours increased a person’s risk of death by 200 percent compared to those who sat for less than 11 hours a day. But a simple tweak could make a big difference: Get up and move around every 30 minutes, and you could lower your chance of death by more than half. Here are 17 ways to get motivated to workout.

woman happy on bed smiling and stretching looking at cameraDavid Prado Perucha/Shutterstock

Myth: Rest days aren’t necessary

“You need recovery days for those muscles to rest, just like you need sleep every day,” explains David Greuner, MD, co-founder of NYC Surgical Associates. “Think of your recovery days as days for your muscles to sleep.” In addition to increasing your potential for muscle strains, stress fractures, and joint pain, says Dr. Greuner, “working out without the proper rest and recovery can lead to bigger issues like extreme fatigue, hormone imbalance, and mood swings.” So take a day or two off after an intense workout, but make sure to incorporate movement in those days to stay limber and active.

Young girl holding in female hands fast food burger, american unhealthy calories meal on background, mockup space for text message or design, hungry person smiling with grilled hamburger front viewMaria Savenko/Shutterstock

Myth: You can burn off last night’s fast food with a trip to the gym

Calories are not interchangeable, because foods aren’t all the same. So, unfortunately, those fries will be staying with you a lot longer than the side salad you probably should have chosen instead. As Men’s Fitness explains, the type of food you’re eating will cause your hormones “to store or burn fat, boost or crash metabolism, and build or break down muscle.” While there’s nothing wrong with splurging once in a while, don’t make it a habit if you really want to lose weight and stay fit. Check out these 11 things that may be sabotaging your weight-loss goals.

Young beautiful Caucasian woman on bed having headache / insomnia / migraine / stressTwinsterphoto/Shutterstock

Myth: Increased exercise will help chronic fatigue syndrome

While exercise improves most health problems, chronic fatigue syndrome (CFS) is not one of them. In fact, according to NPR, even light exercise can make this condition much worse. This is a common misconception even among doctors; the CDC only revised its guidelines about exercise and treatment in 2017, after recommending the exact opposite for the last 30 years, when CFS was thought to be more of a psychological issue. Before embarking on a fitness plan, make sure to discuss it with your doctor first.

In the locker room of the gym. White towel boxing gloves, a bottle of water. advertising water. Accessories athlete. After a workout. Advertising Sports Club. Motivation to sport.marienalien/Shutterstock

Myth: Wipe down exercise equipment with your towel to keep germs at bay

Yes, you should absolutely wipe down equipment, but never use your towel! One study found that 63 percent of exercise equipment at the gym is covered in rhinoviruses—they cause colds; the machines and equipment are also crawling with flu germs and the antibiotic-resistant staph bacteria MRSA. Many gyms offer alcohol-based sprays with paper towels or antibiotic wipes to keep things sanitary—so use them! Other good tips to keep you healthy while you’re getting fit: cover cuts, use a separate towel as a barrier between you and the equipment, and wash your hands post-workout.

Leg Injury. Woman Suffering From Pain In Leg After Workout. Beautiful Girl In Sportswear Sitting And Touching Painful Ankle Injured While Training Outdoors. Sports Injury. High Resolutionpuhhha/Shutterstock

Myth: No pain, no gain

There’s a difference between post-workout soreness and pain. The former is something called delayed onset muscle soreness (DOMS), which happens when you get microscopic tears in a muscle and inflammation. Personal trainer Jeana Anderson Cohen, the founder of ASweatLife.com, says, “Do not push past the pain—listen to the pain to understand what your body needs. If you have tightness in your soft tissue, work on mobility on your recovery day. If your legs are sore, try upper body or cardio.” And if you’re experiencing sharp, shooting, or persistent pains in your muscles, joints, or ligaments, it’s time to see a doctor. These are the 9 signs you’re probably working out too much.

Group of happy young people sitting and stretching legs in yoga studioDean Drobot/Shutterstock

Myth: Yoga can only improve arthritis

According to the Arthritis Foundation, people with arthritis should avoid poses that require balancing on one foot or bending their knees more than 90 degrees. Kundalini and Ananda may also be difficult since they require extended meditation and breathing. Instead, look into gentler types of yoga, including Iyengar, which lets you use a chair to balance. Before you get out your yoga mat, check out these physical issues that could pose a problem for you.

Group of young sporty attractive people practicing yoga lesson with instructor, standing in Warrior Two exercise, Virabhadrasana 2 pose, working out, indoor close up image, studio. Wellness concept fizkes/Shutterstock

Myth: “Hot yoga” is the best yoga workout

People who swear by Bikram—hot—yoga say they reap more benefits than they would with traditional yoga, including increased flexibility and balance, better cardiovascular health, and more calorie-burning. But when you’re exercising for 90 minutes in a room that’s 105 degrees and 40 percent humidity, things can go really wrong. In fact, a recent study by the American Council on Exercise found that some participants’ core body temperature rose to 103 and one reached 104.1, which is medically concerning. As a result, the Council advised that participants increase their water intake and that instructors take more care to gradually adapt people to the heat of the room. So, be aware of the risks, and take a break to hydrate if you start feeling overwhelmed. (Be sure you know the causes of exercise-related chest pain, besides a heart attack.)

Beautiful girl in the gym with a beltMAXIMUMSTOCK/Shutterstock

Myth: Use a weight belt when doing squats to lift more

Squats not only sculpt your lower body—they also stimulate the release of muscle-building hormones, strengthen your core, and improve your flexibility. But if you pile on too much weight and aren’t doing them correctly, they can injure your back, hips, and knees. “If you have to use a weight belt,” says Lagree, “you are not using your core to stabilize the spine and you’re putting too much weight on it, which can lead to serious injuries.” To correct this problem, Lagree suggests keeping your lower back in a neutral position to restrict the range of motion; leaning against a Smith machine can keep your trunk stable, keep the weight on your heels, and make sure that your knees stay aligned with your ankles.

senior sportsman doing lunges with dumbbells in sport center with trainer nearLightField Studios/Shutterstock

Myth: The lower the lunge, the better the results

Lunges strengthen and tone your legs and butt, and they can actually help you avoid knee injury if done properly. If done improperly, you can extend too far and hurt your knees. Lagree says the correction is simple: “Don’t let your knee go out of alignment past the ‘toe line.’ Instead, keep the knee stationary over the ankle. This will reduce the range of motion, but that’s OK because you’ll be working the correct muscles.” He also says to push from the heel, not the toes.

overweight woman working out on training apparatus LightField Studios/Shutterstock

Myth: You can be fat but fit

A study published in 2012 claimed that overweight and obese people weren’t at a higher risk for heart disease and cancer if they were “metabolically fit” and didn’t have diabetes, high blood pressure, or high triglycerides. However, a more recent study in the International Journal of Epidemiology, which analyzed data from more than 1.3 million men in Sweden, found that participants who were a normal weight had a lower risk of death than those who were “obese but fit.” They also found that aerobic fitness decreased the more obese a person was. While body positivity is a good thing, it shouldn’t make you complacent about your fitness and your health. Check out these 18 secrets of women who work out every day.

Man in red hoodie jogging beside the road in the citydjile/Shutterstock

Myth: Morning workouts are best for your metabolism

The reality is, exercising at any time of the day is good for you and will kick your metabolism into high gear. The optimal exercise time for you depends more upon your circadian rhythms and what time your body is most primed for activity. One study indicates that the late afternoon may be when lung and muscle function peak for many people. The problem with morning workouts primarily comes if you’re not a morning person. If you’re losing sleep, your body chemistry will be off and your metabolism can slow down. Here are the 10 best foods to maximize your workout results.

Woman taking break during cycling workout in gym. Female on gym bike doing cardio exercise.Jacob Lund/Shutterstock

Myth: People with asthma should limit their activity levels

To lessen your asthma symptoms, you might want to hit the gym and increase the intensity of your workouts. Yes, you read that right. According to the European Lung Foundation, Danish researchers found that high-intensity exercise was not only safe for non-obese asthmatics—but that it also could improve their quality of life. A combination of exercise and a healthy diet also kept study participants’ symptoms under control 50 percent more than the control group and improved their fitness levels.

Doping anabolic pills bodybuilder bodybuilding muscles fitness studio gym strong muscular manSergey Edentod/Shutterstock

Myth: Take an anti-inflammatory pre- or post-workout to lessen soreness

Before you pop that pill, you should know that it could damage your body instead of helping it. Men’s Journal lists these possible disturbing side effects of anti-inflammatories: They could put undue stress on your kidneys, especially if you’re dehydrated; cause more inflammation by damaging your stomach and colon and setting off an inflammatory response throughout your body; and result in gastrointestinal bleeds severe enough for hospitalization or that even lead to death. So, unless pain management is truly necessary, let your body recover naturally. Find out which everyday medications you shouldn’t take when you exercise.

Portrait of a handsome man sitting on the bench with towel in fitness gymDean Drobot/Shutterstock

Myth: If you’re angry or upset, head to the gym for a great workout

Actually, if you don’t want to have a heart attack, you might want to calm down first. According to a study published in the journal Circulation, you’re twice as likely experience a cardiac event within the hour after being emotionally triggered, and you’re three times more likely to have one if you’ve been emotionally triggered and do intense exercise.

Sad depressed woman suffering from insomnia, she is sitting in bed and touching her forehead, sleep disorder and stress conceptStock-Asso/Shutterstock

Myth: If you exercise at night, you’ll have trouble falling asleep

Your workout, no matter what time of day, will send you off to dreamland a lot easier. According to a review of 66 studies, exercising regularly is actually on par with taking sleep medications and can improve sleep quality. Experts aren’t sure why, but they theorize that exercise positively affects body temperature, metabolic rate, and anxiety levels. So don’t skip that post-work workout because you’re worried it will rev you up too much; if you do, it might sabotage your sleep and your fitness. Check out these 11 workout moves you can do with everyday objects at home.

man slicing cooked medium rib eye steak on board, wide photoUfaBizPhoto/Shutterstock

Myth: You need more protein in your diet

If the protein comes from meat, you probably don’t. In fact, you’re most likely eating too much of it already. Consuming too much can lead to heart disease and weight gain since animal protein tends to be high in saturated fat. Plus, there’s a limit to how much protein your body can actually use, and most Americans eat about double the recommended amount. “For each meal, consuming 2 to 3 ounces of lean meats, poultry, or fish, or half a cup of beans, would be the proper serving size,” says Dr. Greuner.

Senior man stretching by the indoor swimming pool.Halfpoint/Shutterstock

Myth: If you’re over 50, you should stick to low-impact cardio

Cardio is obviously good for your heart health, which is a particular concern if you’re older, but if your exercise focus is too narrow, you’re doing yourself a huge disservice. After 50, bone density and muscle mass decline, and resistance training can help with both of those things, decreasing your risk of falling and breaking a bone. It can also increase your mental fitness: Research indicates that lifting weights can improve your memory, and just 20 minutes can do the trick. Check out the best exercise bikes to stay active year-round.

Attractive young sports woman is working out in gym. Doing cardio training on treadmill. Running on treadmill.4 PM production/Shutterstock

Myth: Running on a treadmill is gentler on your knees than running outside

Impact is impact—whether it’s asphalt or a spinning belt. You might actually be more prone to injury on a treadmill, according to Livestrong. Why? Because you move differently on a treadmill than when you’re on the ground, and because the treadmill surface could be problematic for knees and backs. Another issue: People who regularly use treadmills develop a longer stride, which stretches tendons and ligaments more and could increase the risk of injury and joint problems. That’s not to say that you should avoid treadmills. Instead, pick the right running shoes, and do exercises that strengthen knees and hip joints. Here are 10 running mistakes you probably don’t know you’re making.

Side view of sporty young woman running on sidewalk in morning. Health conscious concept with copy space.Jacob Lund/Shutterstock

Myth: Running is bad for your knees

Running has always come with a caveat: It’s great for your heart, but it leads to arthritis and knee damage. Or does it? Researchers from Brigham Young University, who analyzed the blood and joint fluid of 15 runners, found that 30 minutes of running lowered knee inflammation. While the results were promising, this was a small study, and scientists need to look at the pro-inflammatory markers over an extended period of time, not just immediately after a run. So, don’t discount running; it can lower your chances of a heart attack, breast cancer, and depression—and maybe help your knees.

Cyclist in maximum effort in a road outdoorsRamon Espelt Photography/Shutterstock

Myth: Cycling causes erectile dysfunction and infertility

A recent study of 5,300 male cyclists debunked that myth, even among those who rode for eight and a half hours a week (approximately 200 miles). So casual riders are in the clear to reap the health benefits of cycling, which include calorie-burning, whole-body conditioning, increased cardiovascular health, and an exercise that’s easy on your knees. Unfortunately, the study also found a small link between cycling and prostate cancer in men over 50 who biked more than eight and a half hours per week, but researchers said that the benefits of cycling outweighed that potential risk.

A side shot of a professional slim cyclist riding up a mountainStefaniya Gutovska/Shutterstock

Myth: If you’re not cycling at your max heart rate, you need to push yourself harder

Believe it or not, moving between different heart-rate zones is better for your heart and your workout session. According to Bicycling, this increases your base fitness level, your endurance, and your lactate threshold. Plus, if your intensity is always at the outer edge of your body’s capabilities, you’re raising your risk for injury, fatigue, and other overtraining symptoms—including insomnia, a compromised immune system, and an elevated heart rate. These 50 easy habits that will help you live longer, according to science.

Squats with a barbell, coach helps girl crouch on her shoulders.Parilov/Shutterstock

Myth: Behind-the-head lats pulls are more effective

While there may be a place for this exercise in your routine, an injury is a big risk. The main culprit is incorrect alignment: Unless you have very mobile shoulder joints, it’s hard to keep your spine straight enough. As a result, you could injure your rotator cuff, and if you hit the back of your neck with the bar, you could also damage your cervical vertebrae. For a safer option, WebMD suggests using the pull-down machine (while leaning back a little and holding on with a narrower grip) to bring the bar in front of the body to the breastbone as you pull your shoulder blades down and together.

Close up of metal small dumbbells in a row in the gym. sarocha wangdee/Shutterstock

Myth: Using small weights in a cardio class boosts results

There are a few problems with this myth. For starters, it’s not effective, according to Men’s Health, because you’re not lifting enough weight to build and create lean muscle mass. Second, it’s dangerous, especially for beginners. For example, if you’re in a spin class while attempting this, you might twist your body unnaturally in order to lift the weights, sacrifice correct form, or even drop a weight on yourself accidentally. A much safer, more efficient plan: Focus on one thing at a time, and lift weights on the floor, not while on a bike.

Pregnant lady in black yoga clothes Kaya Shelest/Shutterstock

Myth: Pregnant women should avoid ab exercises

While avoiding ab work when pregnant won’t land you in the hospital, it’s not doing you any favors. If you don’t strengthen your core, you may end up with more lower-back pain, as well as have a longer delivery and a longer postpartum recovery. That said, after the first trimester, you should avoid traditional sit-ups so your uterus doesn’t compress your vena cava, the vein that carries blood to your heart. But a few tweaks can deliver all of the benefits of ab exercises without the risks—either by lying on your side, standing, or using a wedge that raises your heart above your bellybutton. Speak with a doctor and a trainer who can help you make the proper adjustments so that you and your baby stay safe.

Happy pregnant yoga prenatal maternity doing different exercises with fitball. in park on the grass, breathing, stretching, forest. concept of healthy lifestyle and relaxation. Pilates. top view.vhpicstock/Shutterstock

Myth: Too much exercise while pregnant will cause you to deliver early

If you were looking for an excuse to put up your swollen feet, you’re not going to find it here. Scientists once theorized that since exercise releases norepinephrine—it can cause uterine contractions—pregnant women should take it easy at the gym. But a study in the American Journal of Obstetrics disproved that theory. Pregnant women who exercised were not at an increased risk of delivering early and had a lower incidence of gestational diabetes and high blood pressure. Researchers also discovered a big unexpected benefit: These women were more likely to deliver vaginally and avoid a C-section.

Pregnant woman exercising in the gym. Fitness and healthy lifestyle during pregnancy. Pregnant girl with a big tummy during the third trimester goes in for sports.ZephyrMedia/Shutterstock

Myth: You shouldn’t lift weights while pregnant

Doctors often frighten moms-to-be to the point that they don’t want to even pick up their own toddlers. While pregnant women should avoid heavy lifting, they can and should do some moderate resistance training, according to a study from the University of Gothenburg. The benefits, according to lead researcher Karolina Petrov Fieril, PhD, include “improved well-being, relief of pregnancy discomfort—fatigue, headache, nausea, insomnia, and back pain—and a greater sense of control.”

Close up portrait of an attractive young woman drinking water from bottlemimagephotography/Shutterstock

Myth: Avoid dehydration by drinking lots before and during exercise

Most people have been so conditioned to worry about dehydration that overhydration isn’t on their radar. The problem is, when you ingest too many fluids, the sodium in your body is depleted, and you can start feeling symptoms similar to dehydration (nausea, disorientation, headache). Plus, according to Men’s Journal, if you’re overhydrating while working out, you could also develop something called exercise-associated hyponatremia (EAH)—during which your brain cells swell, potentially leading to unconsciousness and even death. To prevent this deadly problem, listen to your body. Experts say that thirst is a reliable gauge for when your body needs water.

Woman Running at snowly winter under sunlight.Andrey Yurlov/Shutterstock

Myth: Outdoor exercise in winter is safe if you’re bundled up

Winter exercise does come with some risks since the cold causes muscles to contract. Your body can get too tight and put you at risk of muscle, joint, and nerve injuries. To prevent this problem, make sure to warm up with some light cardio for 10 minutes when the temperature is between 35 and 45 degrees; tack on an extra five minutes for each 10-degree dip below 35. But if you have a heart condition, you might want to head indoors: Your risk of having a heart attack increases when physically exerting yourself in frigid temperatures. Here are 8 more rules for exercising safely during winter.

making sandwiches with avocado healthy organic food279photo Studio/Shutterstock

Myth: Eating fat will make you fat

It won’t—and it will actually help you burn more fat and lose weight. Of course, that’s only if you’re eating unsaturated fats (both monounsaturated and polyunsaturated) and ones that have omega-3s. According to Livestrong, some studies have shown that people who consume more unsaturated fatty acids have lower BMIs and less abdominal fat, while others indicate that good fat can boost your metabolism. Fat can also keep you full longer and help you build muscle. So make sure to incorporate avocados, olive oil, fish, and nuts into your diet. But Dr. Greuner cautions, “Realize what proper serving sizes are for all your foods. For example, the proper serving size of an avocado is one-fourth of the avocado. Think of that next time you add guac to your Chipotle!”

muscular african american woman sweating from work out in home gymJoshua Resnick/Shutterstock

Myth: You can sweat out toxins

While sweat contains tiny traces of toxins, you won’t be able to eliminate a significant amount that way. That’s what your liver and your kidneys are for—and they’ll do the job better than any sauna. “A more effective route would be to focus on hydration and eating a clean, fiber-filled diet,” says Cohen. “This will help your kidney and liver facilitate their detoxification process and reduce the danger that could come from ignoring these key organs.” If you’re worried about more extreme toxins, like BPA or heavy metals, you should see a doctor.

Athletic sportswoman exercising in gym, squatting while lifting up kettlebell LightField Studios/Shutterstock

Myth: You need to exercise for an hour at a time to benefit

“About six out of seven Americans think that just a little exercise is pointless,” says Lagree. “It’s not! Your body can benefit from even just one minute of exercise.” Science backs him up: According to researchers at the National Cancer Institute and the National Institutes for Health, even a few minutes of moderate to vigorous activity “counts” toward better fitness and better health. That could be jogging for five minutes or even climbing a flight of stairs. Ideally, those little bursts of activity can add up to an hour a day, which, say researchers, cut a person’s risk of death by half. Check out these 60-second exercises that can transform your body.

figure fitness girlAlexander Lukatskiy/Shutterstock

Myth: A “fat-burning belt” will help you achieve awesome abs

You may have seen them on TV, and they look pretty miraculous. But these devices—including abdominal sweatbands, sauna belts, and body wraps—likely won’t help you lose weight and may even be dangerous. Since these bands are often recommended for use during exercise, they interfere with the correct use of ab muscles. Heated sweatbands can also dehydrate you more easily and, in some cases, cause burns. Instead of trying this quick fix, it’s better to sweat out calories the old-fashioned way. Moral of the story: If it sounds too good to be true, it probably is.

Sportive young lady doing crisscross crunch exercise lying on a rug at modern studioUndrey/Shutterstock

Myth: Compression gear will increase your exercise stamina

Athletes might believe differently, but studies show that the supposed benefits of this skin-tight gear may be all in their heads. The Ohio State Wexler Medical Center found that while compression tights reduced muscle vibration, that didn’t lead to reduced muscle fatigue. In fact, according to the study, runners performed the same with and without compression tights. And while that research didn’t reveal any negative results to wearing it, the Los Angeles Times reports that wearing compression clothing—whether it’s exercise gear or shapewear—for prolonged periods of time can put too much pressure on nerves and internal organs, even causing gastroesophageal reflux disease. That said, if you like exercising in compression clothing, just make sure to limit your time in it to the actual workout.

measuring spoons with sports supplements on a black backgrounditakdalee/Shutterstock

Myth: Supplements are essential to health

Just because something is “natural,” it doesn’t mean it’s good for you. According to the National Institutes of Health, there’s two problems here: First, supplements aren’t FDA-approved before they hit the shelves; second, some supplements can cause harmful side effects or interact poorly with certain drugs. For example, vitamin K can make the blood clot drug Coumadin less effective, St. John’s wort can render birth-control pills useless, and vitamins C and E could make chemotherapy less effective. Your health will be better served if you eat a diverse, nutrient-rich diet.

Juicer prepares fresh and healthy juice. juicer juice extractor fresh blender machine conceptPiotr Adamowicz/Shutterstock

Myth: Juicing is a great way to eat your fruits and veggies

The problem is that juicing eliminates a food’s fiber—and your digestive system needs fiber. In a review of studies by the American College of Cardiology, researchers also found that juicing concentrates calories. As Popular Science explains, “You’re basically just drinking sugar water with some vitamins in it.” To at least partially correct this problem, you can add some of the removed pulp back into your drink, but in all honesty, you’d probably be better off just eating an apple and some raw veggies. Here are 10 other incorrect assumptions about weight loss that could hurt your fitness level.

Pregnant beautiful woman eating healthy food and saladsnd3000/Shutterstock

Myth: When you’re pregnant, you’re eating for two

While that’s technically true, you should absolutely not eat for two adults. In fact, according to WebMD, if you’re pregnant with one child, you only need about 340 extra calories per day in your second trimester and 450 more in your third. And for those first 12 weeks? You don’t need to increase your food intake at all. What you should change up throughout your pregnancy, however, is the type of calories that you’re consuming: Switch out sugar-laden foods with empty calories for nutrient-rich foods that will give you more energy, keep you full longer, and provide ample nutrition.

Pregnant woman standing on scales at homeAfrica Studio/Shutterstock

Myth: You should never lose weight during pregnancy

During pregnancy, women hear so much about healthy weight gain that weight loss is not even on their radar. But for overweight or obese women, it should be. As Healthline reports, a study in the British Medical Journal found that embarking on a new healthy lifestyle that included exercise and better nutrition reduced pregnant women’s risk of preeclampsia by 33 percent and gestational diabetes by 61 percent. This could also benefit the babies since maternal obesity is a risk factor for childhood obesity.

Close up shot of fit young man drinking water by the beach after workout. Runner drinking water after exercising.Jacob Lund/Shutterstock

Myth: You need sports drinks to replenish your electrolytes

For high-endurance athletes who exercise for prolonged periods of time, sports drinks are a good way to hydrate and quickly get some electrolytes, potassium, and sodium into the body. The problem is, the majority of people who drink these beverages are not endurance athletes, and they’re downing a ton of sugar. For people who are less active, that could lead to weight gain; for kids, consumption of sports drinks has been linked to childhood obesity. In short: For most people, water is best, and if you do reach for a sports drink, limit your intake and opt for the low-sugar versions. Here are 13 other post-gym mistakes that could sabotage your workout.

Pretty woman running on treadmill with fit young man on backgroundPressmaster/Shutterstock

Myth: Mental fitness has nothing to do with physical fitness

Your body affects your brain more than you may realize, especially as you get older. Researchers at Boston University School of Medicine found that older adults who did well on cardiorespiratory fitness tests also experienced more brain activity while learning and did better on memory tasks than their less-fit peers. And the more fit participants were, the more brain activity they exhibited. While researchers caution that exercise won’t prevent Alzheimer’s or dementia, it could be a promising way to keep some forms of age-related mental decline at bay for longer. So stay active—or get active—to keep your brain at peak performance.

Beautiful senior couple running outside in sunny autumn forestHalfpoint/Shutterstock

Myth: If you have rheumatoid arthritis, avoid high-intensity workouts

To treat this autoimmune disease that targets the joints, doctors will often recommend low-impact cardio. But, according to Healthline, you may be better served by adding some intensity to your workouts. One study published in the European Journal of Applied Physiology found that improved subjects’ cardiovascular health without adversely affecting their joints or increasing pain. Still, always make sure to speak with your doctor before embarking on a more intense exercise regimen.

Fitness woman skipping with a jump rope outdoors. Female doing fitness training in morning.Jacob Lund/Shutterstock

Myth: The more a person exercises, the better

Danish researchers not only bust that myth—but also found that people who exercise too much may actually reverse the benefits of exercise. Subjects were studied over 12 years, and those who ran at a fast pace for more than four hours a week and more than three days a week had the same risk of dying as those who barely exercised at all. So what’s the optimal intensity and amount of exercise for a longer life: a slow to moderate pace of one to 2.4 hours, less than three times a week.

Sporty young woman lying on yoga mat doing sit-ups in gym. Top view of muscular woman doing abs crunches.Jacob Lund/Shutterstock

Myth: Bicycle crunches are a foolproof way to exercise your entire mid-section

So much can go wrong with the basic bicycle crunch, the staple of every exercise class. As you twist back and forth quickly, you’re putting your lower back at risk for herniated discs and muscle spasms. Also, because you generally hold the back of your head as you perform this exercise, you could suffer a cervical spine injury as well. Experts suggest being more methodical about this movement by slowing down significantly. Don’t miss these 8 myths you need to stop believing about ab work.

Trail runner athlete using her smart watch app to monitor fitness progress or heart rate during run cardio workout. Woman training outdoors on mountain rocks. Closeup of tech gear.Maridav/Shutterstock

Myth: If you want to lose weight, get a fitness tracker

That neat little gadget may be sabotaging your weight loss. One study published in the Journal of the American Medical Association found that people who didn’t use one lost five more pounds over the course of a year than those who did. Another study from Stanford University and the Swedish School of Sport and Health Sciences found that fitness trackers didn’t provide accurate calorie-burning numbers; as a result, people may stop their workouts prematurely when they think they’ve already reached their daily fitness goal. That’s not to say that you should ditch your fitness tracker. Technology is improving, and they’re a good motivator for people who lead a more sedentary lifestyle, reminding them to get up and go more than they normally would.

Athlete runner feet running on treadmill closeup on shoe. Jogger fitness shoe in the background and open space around him. Runner jogging training workout exercising power walking outdoors in city.WAYHOME studio/Shutterstock

Myth: Walking doesn’t really do anything for you

Don’t discount a simple walk. Walking can work some serious health miracles. According to Harvard Health, studies show that it can reduce your risk of developing breast cancer, help with joint pain, strengthen your immune system, and counteract the effects of the body’s obesity-promoting genes. Plus, even a 15-minute walk can keep your craving for sugar at bay. Next, find out the 35 health secrets your body is trying to tell you.