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10 Nutrition Myths, Debunked

Find out the truth about fat, salt, carbs and detox diets


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When it comes to eating healthy, one of the biggest barriers is a flood of unreliable information.

Conflicting headlines, fad diets and misinformation make it difficult to sort out what’s really good for you and what’s harmful. Creating more uncertainty: manufacturers that slap misleading food labels on their products, and social media influencers with no nutrition expertise who tout specific eating habits or diets.

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Here are 10 of the most common nutrition myths and the truth about each.

1. Myth: All fat is bad

Fat got a bad rap in the ’90s, when low-fat diets were all the rage, and many Americans are still confused about the role of fat in a healthy diet.

We now know that all fats aren’t created equal, says Teresa Fung, a nutritional epidemiologist and professor of nutrition at Simmons University in Boston.

Animal fats, which are more saturated, are linked to cardiovascular disease. But the healthier monounsaturated and polyunsaturated fats found in fish, avocados, olives and olive oil, eggs, nuts and seeds can lower your risk of cardiovascular disease and death.

Although all types of fats are high in calories, fats “stay in the stomach longer,” Fung says, “so you are satisfied for longer and you don’t reach for a snack as quickly.”

2. Myth: The best way to cut sodium is to put aside the salt shaker

The vast majority of Americans consume too much salt, and if you have high blood pressure, slashing your sodium intake could be a matter of life and death.

But because most of our sodium in the United States comes from prepared foods, just avoiding the salt shaker at dinner isn’t going to make a big difference, Fung says.

Breads, salad dressings, pasta sauces, canned beans, cheese, and many processed foods and packaged snacks are loaded with sodium, she says. Even boneless, skinless chicken breasts can be injected with a brine that raises sodium levels. Restaurant food is also filled with salt, with some packing the amount of sodium you should have in a day into just one meal, according to a study in the Canadian Journal of Public Health.

Fung recommends cooking at home as often as possible, comparing labels and choosing low-sodium versions of packaged and prepared foods.

3. Myth: Foods with “whole grain” or “multigrain” on the label are always healthy

You know that foods made with whole grains are healthier than those with refined flour, but labels can be misleading.

“Made with whole grains” and “multigrain” may sound healthy, Fung says, but often they mean a product contains only a small amount of whole grains, while the rest is refined.

Fung recommends looking for products labeled “whole grain” or “whole wheat,” which means they’re made with at least 51 percent whole-grain ingredients. Even better, choose one that says “100% whole grain.” You can also look at the ingredient list to make sure a whole grain is listed first.

4. Myth: All sugar and carbs are bad — even in fruit

Sugar-free and low-carb diets like keto and paleo are popular, which might lead you to believe that anything with carbs or sugar is bad for your health. However, there’s a big difference between the natural sugars in fruits and vegetables and the added sugars and refined starches in processed foods, says Dariush Mozaffarian, M.D., a cardiologist, public health scientist and director of the Food is Medicine Institute at Tufts University.

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Cutting out added sugars and refined carbs is probably the best thing you can do for weight control, Mozaffarian says.

But don’t stop munching on fruits and vegetables. Not only do they contain vitamins, minerals, fiber and other healthy micronutrients, but studies show that eating more of them is tied to a longer life span and reduces your risk of death from all causes.

5. Myth: Fresh produce is healthier than frozen

Nothing beats picking up fresh raspberries or peas at the farmers market. But if it’s the dead of winter, with no local produce to be found, rest assured that you won’t be missing out on any nutrients if you shop the frozen foods aisle, says Valter Longo, a gerontologist, cell biologist and director of the Longevity Institute at the University of Southern California.

Frozen produce tends to be picked at the peak of ripeness, and studies show that frozen foods have as many vitamins and antioxidants as fresh ones, and in some cases even more. What’s more, the longer you store fresh produce, the more of its nutritional value it loses, research shows.

“Food can oxidize and get contaminated over time,” Longo says. “If you pick berries and freeze some and leave some out, the ones that were frozen might be fresher than the ones that sat around on a bench or in a crate.”

6. Myth: Canola oil is toxic

You might have seen social media posts that claim canola oil, sunflower oil and other seed oils are toxic, but science doesn’t back that up, Mozaffarian says. “There is very clear evidence for them being beneficial,” he says. 

Canola oil is very low in saturated fat and is high in healthy monounsaturated fats, omega-3s and phytosterols, which are known to reduce the absorption of cholesterol in the body. A 2020 review published in the journal Nutrition, Metabolism & Cardiovascular Diseases found that canola oil lowered cholesterol and improved cardiovascular risk factors. 

Other seed oils, including soybean oil and sunflower oil, are also healthy options, Mozaffarian says. Of course olive oil is known for having heart benefits and may even lower risk of early death.

7. Myth: Gluten-free foods are healthier

Gluten is a protein found in grains including wheat, barley and rye. People with celiac disease must eliminate gluten from their diets to prevent damage to their intestinal tracts and other parts of their bodies. And for those with gluten sensitivity, eliminating gluten can help with symptoms of bloating, diarrhea or abdominal pain, according to Harvard Medical School.

For the rest of us, however, gluten-free does not necessarily mean healthier, Mozaffarian says.

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He said he would like to put to rest the idea that any single word or characteristic can define healthier food, whether it’s organic, local, natural, vegetarian or gluten-free.

“All of those are terms that have some relevance, but you can’t really define a healthy diet by a lack of something,” he says. “You can have natural, gluten-free, organic food that is still terrible for you.” 

8. Myth: Eat six small meals a day instead of three large ones

The idea behind this myth is that eating small, frequent meals could boost your metabolism so you burn more calories.

However, studies show that splitting the same number of calories into six meals rather than three does not help with daily energy expenditure, weight loss or fat loss, Longo says. In addition, University of Colorado researchers found that those who ate smaller, more frequent meals ended up feeling hungrier than their counterparts who ate less often.

A third problem, Longo says, is that “in the real world, if people are told to eat five or six small meals, they are just going to eat more, or eat more of the wrong things.”

Longo recommends eating breakfast and then eating one other big meal and a third smaller meal or snack each day.

9. Myth: It’s a good idea to do a detox or cleanse

Different detox diets and juice cleanses are popular on social media, but studies show few benefits and a risk of harm.

A 2014 review study, for example, found no evidence that detox diets eliminate toxins from the body or help with long-term weight loss. Even if you lose weight during a cleanse, a 2017 study in the journal Nutrition and Obesity found that most people actually gain weight when they resume eating normally.

Perhaps more concerning, cleanses can cause serious side effects including gastrointestinal problems, protein and vitamin deficiencies, dehydration, and electrolyte imbalances, according to the National Center for Complementary and Integrative Health.

10. Myth: “Calories in, calories out” is all that matters

It’s true that if you burn more energy than you consume, you will probably lose weight, at least in the short term. But for your overall health, “calories in, calories out” is an oversimplified notion that doesn’t account for the influence different types of foods have on your overall health, Mozaffarian says.

Two foods with the same number of calories can have different effects on your hormones, gut microbiome and metabolism, he says. A handful of nuts, for instance, will take longer to digest compared to a bag of Cheetos. And newer research shows starchy and sugary foods tend to contribute to visceral fat, which has been linked to heart disease and other conditions, while fatty foods tend to contribute to subcutaneous fat, which is less harmful.

For overall health and weight loss, Mozaffarian recommends choosing nutrient-dense whole foods over processed foods with added sugar and refined carbohydrates.

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