5 Myths Even Health Care Professionals Still Believe About Health, Nutrition, and Fitness

5 fitness and nutrition myths even health care professionals still believe.

When you visit a health care professional you’d like to think they offer you the best nutrition and fitness advice, especially when you consider how important each is for staying healthy and preventing disease. Unfortunately, doctors get little education in the areas of nutrition and fitness, so the advice you get in these areas may be lacking. Here are some of the most common fitness and nutrition myths that are still prevalent in the health care community.

Fitness and Nutrition Myths #1: Walking is the Best Form of Exercise

Many doctors still believe the most effective form of exercise is walking. It’s true ANY physical activity has health benefits, but after a few weeks of walking at the same pace, your body adapts and no longer feels challenged. Plus, most research shows vigorous exercise has the advantage in terms of heart health and reducing the risk for chronic disease. As a study published in the journal Circulation points out:

“Exercise performed at higher relative intensities has been found to elicit a greater increase in aerobic capacity and greater cardioprotective effects than exercise at moderate intensities.”

High-intensity exercise isn’t necessarily for everyone. Some individuals have health problems that preclude vigorous workouts, but for those who don’t, vigorous exercise in the form of high-intensity interval training offers benefits you won’t get by taking a daily 30-minute walk. Let’s not forget about the importance of strength training too! Too many health professionals fail to bring up that topic despite the fact that it helps prevent sarcopenia, bone loss, and loss of functionality with age. Don’t wait for your doctor to tell you to lift weights – just do it.

Fitness and Nutrition Myths #2: High-Impact Exercise Increases the Risk for Osteoarthritis

Some health professionals still believe high-impact exercise is damaging to the joints and speeds up the onset of knee osteoarthritis, despite a lack of evidence. Factors that DO increase the risk for osteoarthritis are anatomic problems affecting joints, obesity, previous joint injury, and weakness of the muscles surrounding a joint. Exercise may actually lower the risk for osteoarthritis by helping to prevent weight gain and obesity and by strengthening the muscles that support the joints. For example, strengthening the quadriceps muscles in the thighs helps support the knee joint. With weak quadriceps muscles, your knees are less stable when you squat down or do other activities that place stress on the knees. Strong quadriceps help keep your knees stable and more resistant to trauma and shock when you move your legs.

In one study, researchers looked at the effects a high-impact exercise program involving jumping would have on middle-aged and older women with patellofemoral joint osteoarthritis (arthritis of the kneecap). At the beginning and end of the 12-month study, they measured the thickness of the cartilage in the kneecap. The group who did high-impact exercise had a 7% increase in cartilage thickness. Although high-impact exercise isn’t as joint unfriendly as previously thought, don’t overdo it. Combine high-impact exercise with lower impact workouts and get medical guidance before doing high-impact exercise if you’ve had a joint injury or have significant arthritis.

Fitness and Nutrition Myths #3: A Low-Fat Diet is Best for Weight Loss and Health

Many health care professionals STILL believe eating fat makes you fat. Yet, despite the proliferation of low-fat food products, it’s done nothing to curb the obesity epidemic. A study involving 50,000 women called the Women’s Health Initiative showed those on low-fat diets experienced little or no weight loss.

The problem with low-fat diets is they’re often higher in sugar and processed carbohydrates. With the growing problem of insulin resistance, more focus needs to be on eating whole, unprocessed foods without added sugar. In reality, the best eating plan depends on the individual. Each of us is different from a genetic standpoint, with a distinctive hormone profile and tolerance for carbohydrates. A low-fat diet may work for some people but be a disaster for someone with insulin resistance. One way to find out if you’re insulin resistant is to check your insulin level after drinking a sugary drink, a test doctors don’t do very often.

One eating plan that almost everyone can benefit from is a Mediterranean-style diet that emphasizes whole, unprocessed foods- fruits, vegetables, whole grains, nuts, lentils with moderate amounts of HEALTHY fats, for example, the monounsaturated fats in olive oil.

Fitness and Nutrition Myths #4: Eating a High Protein Diet is Harmful

Ask some health care professionals about adding more protein to your diet and they’ll tell you it’s harmful to your kidneys. This idea became popular after animal studies showed high-protein diets decrease survival in animals with pre-existing kidney disease. There’s no evidence that eating a high-protein diet damages the kidneys of people with normal kidney function. In fact, some studies show older people can benefit from adding more protein to their diet. Diets higher in protein help protect the elderly against loss of muscle mass and frailty.

As with most things, moderation is key. There’s no benefit to consuming triple the recommended protein intake of 0.8 grams per kilogram of body weight, although you do need more protein if you strength train or do high-intensity aerobic exercise or long periods of endurance exercise. It’s not unreasonable to increase your protein intake to 1.2 to 1.6 grams per kilogram of body weight if you work out. Going higher than this and you run the risk of nutritional deficiencies, especially fiber. It’s also wise to diversify your protein sources, consuming more plant-based protein rather than getting most of your protein from animal sources. Some studies link consumption of red meat, especially processed meat, with an increased risk for certain types of cancer, especially colon cancer.

Fitness and Nutrition Myths #5: Drink 8 Ounces of Water Daily for Health

Yes, it’s important to stay well-hydrated, especially if you exercise or live in a hot or humid environment, but there’s no evidence that you need to drink eight 8-ounce glasses of water daily or that your health will benefit as a result. How did this myth get started? In 1945, the National Food and Nutrition Board published a state saying adults should consume 2.5 liters of water daily. They also pointed out that most people get a portion of this amount from food. Somewhere along the way, the idea of drinking 2.5 liters (about 8 glasses) stuck but the part about getting a portion from food fell by the wayside.

Most research found no link between drinking large amounts of water and a lower risk for health problems like heart attack, stroke, or kidney disease and getting 8 glasses daily isn’t linked with reduced mortality. One possible benefit of drinking this amount of water daily, based on a study is a reduced risk for bladder cancer. This makes sense since you’re cleansing your bladder of potential toxins when you do.

Don’t forget, you can meet your fluid requirements by drinking other beverages, including tea and coffee. Drinking coffee and tea are linked with a variety of health benefits too.

The Bottom Line

Old myths die slow and perceptions change slowly in the field of medicine. Now you know the truth about some of the most common health, fitness, and nutrition myths.



J Anat. 2009 Feb; 214(2): 197-207. doi:  10.1111/j.1469-7580.2008.01013.x

Berkeley Wellness. “Is Intense Aerobic Exercise Best?”

J Anat. 2009 Feb; 214(2): 197-207.doi:  10.1111/j.1469-7580.2008.01013.x.

Bottom Line Health. “Even if You Have Arthritis, High-Impact Exercise Can Help Your Knees”

Dr. Mark Hyman. “Why Eating a Low-Fat Diet Doesn’t Lead to Weight Loss”

Harvard School of Public Health. “Low-Fat Diet Not a Cure-All”

Live Science. “High-Protein Diet Raises Cancer Risk As Much As Smoking”

Int J Vitam Nutr Res. 2011 Mar;81(2-3):109-19. doi: 10.1024/0300-9831/a000061.

FiveThirtyEight Science. “You Don’t Need 8 Glasses of Water A Day”


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