19 Nutrition and Diet-Related Myths To Watch Out For

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Last Updated on October 7, 2020 by Michael Joseph

There are many different nutrition and diet-related claims that are evidence-free.

Such claims can be unhelpful for individuals who are attempting to make healthier nutritional choices.

However, given that there are so many myths, it can be challenging to separate the truths from the falsehoods.

This article lists some of the most prevalent nutrition myths and explains why each one is misleading.

Person Confused By Different Nutritional Topics.

1) There’s One Perfect Way To Eat For Everyone

Log on to your social media platform of choice, and you’ll be able to find thousands of anecdotes about people who have improved their health with a plant-based diet. Many of these people will also strongly advocate for the diet as “the solution” for all kinds of problems – for everyone.

However, thousands of other people will claim that a strict ketogenic diet is the only solution to “rescue your health.”

To put it another way: people can be very passionate about dietary systems that worked for them. 

In truth, different diets work for different people, and there is no need for the way someone eats to have a name tag. According to randomized clinical trials, low-carb diets can result in weight loss and improvements to numerous different health markers (1, 2, 3).

However, the same is true for low-fat diets, too: human clinical trials show that high carbohydrate diets can result in weight loss and improvements to various health metrics also (4, 5, 6).

Personal preference is critical. If someone finds success on a vegan/ketogenic/paleo/high-protein or any other diet, then that is great. The most important thing is to follow a way of eating that you enjoy, that provides ample protein, sufficient vitamins and minerals, and carbohydrate/fat sources as preferred.

A diet that doesn’t meet personal dietary preferences is unlikely to be sustainable, and an enjoyable way of eating plays a big part in dietary adherence (7).

Key Point: There’s no one perfect diet for everyone, and a range of different ways of eating can be successful.

2) Fat Is Bad For You

While it is true that some types of fat are associated with detrimental health outcomes, this does not mean that all dietary fat is bad for you.

Past studies have strongly suggested that trans fat may cause harm, with a systematic review and meta-analysis of 12 large observational studies demonstrating that a higher intake of trans fat increased both total mortality and cardiovascular mortality (8).

It is also true that specific saturated fatty acids (mainly lauric, myristic, and palmitic acid) tend to increase LDL cholesterol levels when consumed in high amounts. LDL is an independent risk factor for cardiovascular disease (9, 10).

However, plenty of foods that contain saturated fat also offer a wide range of beneficial nutrients, and not all saturated fatty acids increase LDL. For instance, stearic acid (as found in cocoa/chocolate) may potentially even lower LDL (11).

Furthermore, many other types of dietary fat are associated with health benefits:

  • A Cochrane systematic review on omega-3 intake examined 28 randomized controlled trials that exhibited a low risk of bias and lasted for longer than 12 months. The results demonstrated that increased omega-3 intake likely slightly reduced mortality from heart disease (12).
  • Monounsaturated fatty acids (from sources such as olive oil) are consistently associated with lower mortality in rigorous systematic reviews of the evidence (13, 14).
  • In a further Cochrane systematic review on polyunsaturated fatty acids, the researchers analyzed 49 randomized controlled trials featuring 24,272 participants. The results found that increasing polyunsaturated fat intake probably slightly decreases heart disease events and deaths (15).

Therefore, no, as a blanket statement, fat is not “bad for you.”

Key Point: While some types of dietary fat may have detrimental effects, the blanket claim that all fat is bad for you is non-evidence-based.

3) Carbs Are Bad For You

While some people claim that fat is bad, others insist that all dietary carbohydrate is bad for you.

The claim usually sounds something like this:

  • Carbohydrate-containing foods increase blood sugar levels after a meal.
  • Higher fasting blood sugar levels are associated with increased risk for type 2 diabetes, cardiovascular disease, and all-cause mortality (17).
  • Therefore, carbohydrates are bad.

However, there is a big difference between fasting blood glucose levels and postprandial blood glucose (‘postprandial’ simply means after a meal).

Fasting blood glucose levels represent the amount of sugar in the blood when we haven’t eaten, and they are usually taken after an overnight fast. In contrast, postprandial blood glucose increases are temporary, and in healthy individuals, blood glucose only rises slightly and returns to normal levels within 2-3 hours (18).

Additionally, providing we don’t consume excessive amounts of carbohydrates, they are stored as glycogen and used by the body to meet energy demands (19).

In other words: no, carbs don’t turn to fat.

That said, one element of truth in the idea of some carbohydrates being “bad” revolves around carbohydrate quality.

Generally speaking, whole-food carbohydrates have a lower impact on blood sugar levels, contain higher fiber content, and they are associated with beneficial health outcomes. These foods include fruit, vegetables, lentils, and genuine whole grains (20, 21).

In contrast, refined grains, sugars, and sugar-sweetened beverages have a more significant impact on blood sugar, and they contain little nutritional value. At higher intake levels, they are associated with detrimental health outcomes (22, 23).

Key Point: The truth: like anything else, carbs can be problematic in excess. It is also better to focus on whole-food carbohydrates rather than refined carbs. However, carbs aren’t inherently bad.

4) “X” Diet Is Unsustainable

On a population level, the majority of weight-loss diets fail. The statistics are quite clear on this, and a meta-analysis examining 29 long-term weight loss studies found that (24):

  • Participants regained more than 50% of their lost weight within two years.
  • 80% of participants had regained their weight at the five-year mark.

However, the blanket dismissive claim that a particular diet is unsustainable for everyone is borne out of ignorance rather than evidence.

While one person may struggle to adhere to a particular diet, others may thrive on it.

Also, research on dietary adherence has shown that some dieters have been successful following a wide range of diets.

For instance, the DIRECT trial was a long-term randomized controlled trial involving 322 participants that measured adherence to various diets at the 24-month mark. In this particular study, the overall rate of compliance to three different diets—low carb, ‘Mediterranean,’ and low fat—was 85% (25).

As previously stated, different diets can work for different people – the key is to find a sustainable and enjoyable diet that suits the individual. Support networks and supervision can also play a critical role in adherence, particularly in the early stages of a diet (26, 27).

Key Point: A particular diet that is unsustainable for one person might be the perfect fit for another.

5) Healthy Food Is Expensive

It is reasonably easy to find claims that people eat poorly because healthy food is too expensive. First of all, there is a wide range of potential reasons to explain the way people eat, and these are beyond the scope of this article.

However, there are some elements of truth to the idea that socioeconomic factors influence dietary habits. For underprivileged people, it can be difficult to afford foods such as fish and vegetables when processed foods often provide more calories per dollar.

If someone has to feed a family and money is short, then it’s understandable how a dollar pizza may appear more attractive than buying a range of ingredients to make a meal.

However, it is a myth that all healthy food has to be expensive:

Firstly, buying “conventional” meat and produce isn’t necessary, and there is little difference between conventional and (more expensive) organic food. Organic foods still use pesticides, and the only difference is that the ingredients in those pesticides were at one point extracted from a natural source (28, 29, 30).

For more information on this, there is an excellent article here:

Mythbusting 101: Organic Farming > Conventional Agriculture

Plenty of nutritious foods are available at reasonable prices.

Here are several reasonably nutritious, cheap food options that may fit a wide range of diets:

  • Canned sardines
  • Dried beans and legumes
  • Eggs
  • Frozen ground meat
  • Frozen fruit and vegetables
  • Potatoes
  • Wholegrains

Expensive berries, organic wild fish, and the latest superfoods from faraway lands aren’t necessary for a healthy diet.

Key Point: Nutritious food doesn’t have to be expensive.

6) Eating Fruit Causes Weight Gain

Boy and Girl Eating Fruit From a Fruit Bowl.

The idea that eating fruit is in some way responsible for weight gain is quite a common claim to come across.

However, based on the available evidence, this is just a myth.

This evidence-based review lists dozens of different studies which demonstrate that fruit intake appears to have an inverse relationship with weight gain:

  • Energy intake from fruit consumption has gone down as rates of obesity have increased.
  • Fruit contributes very little energy to the average person’s diet.
  • Greater intakes of fruit are associated with weight loss.
  • General calorie intake from added fats and added sugar is over ten times higher than from fruit intake.
  • Randomized controlled trials demonstrate that higher fruit intake does not lead to weight gain.

The truth is that overeating anything can lead to weight gain, but fruit is one of the least-deserving foods of blame.

Key Point: For the vast majority of people, fruit intake is not a factor in gaining weight. According to the available evidence, fruit is inversely associated with weight gain.

7) Eating Fat Causes Weight Gain

Another old, yet still common, misconception about dietary fat is that “fat makes you fat.”

If fat indeed did cause people to gain weight, then it would be impossible for people to lose weight on low-carb, high-fat diets. However, numerous human clinical trials demonstrate that these diets can lead to significant weight loss for participants (31, 32, 33).

Once again, it is worth noting that too much of any food, whether candy, avocados, rice, or cheese, can lead to weight gain.

In other words, dietary fat intake will only contribute to weight gain when the overall diet features an excessive amount of food/energy.

Key Point: Fat doesn’t make you fat (unless you eat too much of it).

8) “Fat-Burning Foods” Are Important For Weight Loss

If you venture onto the influencer areas of Instagram and other social media networks, it is easy to come across numerous weight-loss claims.

Many of these claims will regard the use of “fat-burning” foods and drinks. Unfortunately, the stories you may hear about losing 10 kilograms in a month from drinking a special fat-burning tea are nothing more than science-fiction.

It is true that certain drinks, such as green tea and coffee, may slightly impact metabolism and increase energy expenditure due to their caffeine content and polyphenols such as EGCG (34, 35).

Some studies suggest these drinks may slightly contribute to weight loss, but there is limited evidence for this. Further, the results are not statistically significant (meaning the effect size is small) (36, 37).

Overall, there is little available evidence to support any food having a unique fat-burning effect.

The best ways to “burn fat” are the same as they have always been: eating less food, exercise/resistance training, and higher activity levels in general.

Key Point: The idea that eating a specific food “burns fat” belongs to the category of myths.

9) We Should Avoid Antinutrients In Vegetables

Another common nutrition myth is the idea that we should avoid vegetables that contain antinutrients such as oxalate and phytate.

Oxalate

The first of the above-mentioned antinutrients, oxalate, is a naturally occurring substance in foods such as almonds, spinach, and potatoes (with skin) that can bind to calcium during the digestive process (38).

For some individuals, particularly those at risk of kidney stones, high dietary oxalate intake may potentially lead to the formation of calcium oxalate stones (kidney stones) (39).

However, some people use this scenario to promote the idea that everybody should avoid foods containing oxalate.

Firstly, the human body produces large amounts of oxalate as a natural part of metabolism, whether we consume dietary oxalate or not. In this regard, oxalate is a metabolic end-product of ascorbic acid (vitamin C) and general metabolism (40, 41).

There is also a lack of human clinical evidence to suggest that dietary oxalate is uniquely problematic for otherwise healthy individuals.

That said, it is probably wise to be cautious and avoid juicing pounds of raw green vegetables every day, particularly for people with kidney issues. So-called “juice cleanses” have been linked to the formation of oxalate crystals in several case studies (42, 43).

Phytate

Phytate, otherwise known as phytic acid, is the storage form of phosphorus and an antinutrient that can partially inhibit the absorption of minerals such as iron (44).

Among other foods, we can predominantly find phytate in foods like legumes, nuts, and whole grains (45).

Firstly, a specific food containing phytate isn’t a good reason not to eat it. Foods also contain a wide range of other nutrients such as protein, fiber, fats, and essential vitamins and minerals.

Secondly, evidence suggests that the human body adapts to higher phytate intake. A study in this area demonstrated that the inhibitory effect of phytate decreases over time for participants on a high-phytate diet (46).

It is also worth remembering that not everything in nutrition is black and white.

Like many other foods and nutrients, phytate can also have some beneficial effects.

As an example, human clinical trials in patients with type 2 diabetes have demonstrated that increasing phytate intake lowers levels of advanced glycation end-products (AGES) in the blood (47).

This is a good thing because higher levels of AGES are associated with higher oxidative stress levels and an increased risk of age-related diseases (48, 49, 50).

Key Point: Antinutrients are real, and it is worth being aware of their potential effect. However, most antinutrient-containing foods are also very nutritious and can significantly contribute to a healthy diet.

10) Certain Foods Are “Bad” Because They Contain Sugar

One and a Half Fresh Oranges.

Certain components of food are often blamed for health issues, particularly by the media and diet activists. One such component is sugar.

In truth, sugar has many drawbacks: it is devoid of nutrients, it can have a large impact on blood sugar levels, and most of us consume too much of it. However, just because a food contains naturally-occurring sugar doesn’t mean it is “bad” for us.

Despite this, it is easy to find claims that fruit contains “too much sugar” and thus we should avoid it. The truth is that fruit is not just sugar, and it also contains fiber, polyphenols, and a range of essential vitamins and minerals. The glycemic impact of whole fruit is much lower than sugar or fruit juice too.

Also, if fruit intake were truly bad for us because it contains sugar, then the available studies would demonstrate this.

Yet they do not.

Systematic reviews and meta-analyses of large observational studies, featuring millions of participants, have found that higher fruit intake is associated with lower all-cause mortality and a lower risk of chronic disease – in a dose-dependent manner (51, 52).

Key Point: Just because a whole food contains naturally-occurring sugars does not mean that it is bad.

11) Certain Foods Are “Bad” Because They Contain Saturated Fat

Another much-maligned component of food is saturated fat.

However, as previously mentioned, judging food by its saturated fat content requires nuance, and both the amount and type of saturated fatty acids are important. Yet some claims push the idea that any food which contains saturated fat is “bad” for you.

While veganism is an understandable ethical choice for some people, some proponents of the diet use scaremongering and intellectual dishonesty to promote it. For example, their claims might be that we shouldn’t eat dairy or even salmon because it contains saturated fat.

Such assertions ignore the fact that many saturated-fat-containing foods are associated with improved or neutral health outcomes.

For a quick example:

  • Systematic reviews of the available evidence show that fermented dairy products are associated with a neutral/lower risk of cardiovascular disease and all-cause mortality (53, 54).
  • Despite containing large amounts of saturated fat, cheese is not associated with an increased risk of all-cause mortality. Some studies suggest that it may even lower the risk of cardiovascular mortality (55, 56, 57).
Key Point: Just because a food contains saturated fat does not mean that it is bad for you.

12) High Omega-6 Intake From Food Causes Inflammation

There are two essential fatty acids (known as EFAs) that the human body requires. These are omega-3 and omega-6 (58).

The first of these, omega-3, is usually mentioned alongside its anti-inflammatory properties and potential health benefits (59).

In contrast, omega-6 has specific appears to play an important role in blood clotting and modulating wound healing (60).

For this reason, it has been hypothesized by various researchers that high intakes of omega-6 may have detrimental pro-inflammatory effects (61, 62).

However, evidence from observational studies and human clinical trials appears to question this premise:

  • In a randomized controlled trial featuring 67 participants, high daily omega-6 intake over 10 weeks had no impact on markers of oxidative stress or inflammation (63).
  • In the Kuopio Ischaemic Heart Disease Risk Factor Study, which involved 1287 male participants, serum omega-6 levels were not associated with inflammation. In this study, participants with higher serum levels of linoleic acid (the primary omega-6 fatty acid) had lower levels of C-reactive protein, a major marker of inflammation (64).
  • A Cochrane systematic review of 19 randomized trials featuring 6461 adults examined the effect of increasing omega-6 intake on cardiovascular risk. This rigorous review demonstrated that higher omega-6 intakes had little impact on most outcomes, but that it may slightly reduce the risk of cardiovascular events like a heart attack (65).
  • A systematic review of 15 randomized controlled trials analyzed the impact of high omega-6 intake on inflammatory markers. Analyzing the results of their study, the authors concluded that “virtually no evidence is available from randomized, controlled intervention studies among healthy, noninfant human beings to show that addition of LA to the diet increases the concentration of inflammatory markers” (66).

While omega-6 has some pro-inflammatory properties, the existing evidence from human studies doesn’t support the idea that higher dietary intake causes inflammation.

Key Point: Dietary omega-6 intake doesn’t appear to cause inflammation.

13) Calories Don’t Matter

A prevalent social media myth is the claim that “calories don’t matter.”

This claim is simply untrue: overall energy balance, governed mainly by the amount of food we eat, is the primary determinant of weight gain or weight loss (67, 68).

However, just because total calorie intake matters does not mean that we have to actually count calories, which is an altogether different argument.

Some individuals find calorie counting useful, yet others may find it unnecessary or unhelpful. Whether we prefer to track calories or not, though, the total amount of daily calories we consume is vital for weight control.

It is worth noting that this does not mean calories are the only thing that matters. Both the amount and quality of the calories we eat matter for overall health.

Key Point: Tracking calories isn’t essential, but overall energy intake is an important part of weight control.

14) The Glycemic Response To Food Is Always the Same

The glycemic index (GI) and glycemic load of a particular food represent the impact that food will have on blood sugar levels.

For example, a high GI food will have a more significant effect on raising blood sugar than a low GI food which contains an equivalent amount of carbohydrates (69).

According to Harvard Medical School, apples have a GI of 36, white rice has a GI of 73, and whole milk has a GI of 39 (70).

Despite these numbers, many people hear that the GI of a particular food is a specific figure and assume that the glycemic response to that food will always be the same.

However, this is not true.

The glycemic response to food depends on the entire meal

In truth, the glycemic response to a particular food can change significantly depending on other foods it is eaten alongside.

Numerous studies have demonstrated this to be the case, and here are two such examples:

  • The glycemic index of boiled potatoes is 78. In a study investigating how the GI of food can change, mashed potato eaten by itself had a GI of 103. However, when the researchers mixed the potato with oil and served it alongside a source of protein (chicken breast), the GI fell to 54 (71, 72).
  • Adding coconut oil or olive oil to bread significantly decreased the glycemic response in healthy men compared to the glycemic response in men eating the bread alone (73).
Key Point: The glycemic response to food depends on the entire meal rather than the glycemic index/load of one ingredient.

15) Artificial Sweeteners Are Dangerous

A Glass Bottle of Diet Coke.

Artificial sweeteners, such as aspartame, can be found in a wide range of products, and they are particularly prevalent in diet drinks. Critics of such sweeteners often claim that they are dangerous and linked to various health issues.

The truth is that research is ongoing in this area, and more and more studies are being conducted every year to investigate the potential health effects of different sweeteners thoroughly.

However, the consensus from the existing evidence does not appear to support the assertion that these products are harmful. For instance, systematic reviews of existing trials have demonstrated that there is no apparent association between artificial sweetener intake and cancer incidence (74, 75).

Regarding their effect on body composition, the data from existing systematic reviews is more interesting (76, 77, 78):

  • Some observational studies find that people who consume more artificial sweeteners have higher body weight and a higher risk of metabolic syndrome than those who do not. However, this could be just because people who drink more “diet” drinks are often those who are trying to lose weight.
  • Randomized controlled trials demonstrate that artificial sweeteners such as aspartame and sucralose generally have no impact on blood glucose or body composition. However, some longer (>12 months) studies suggest they may slightly help with weight loss.
  • The consensus is that the existing evidence on artificial sweeteners and body composition is inconclusive.

For more information, there is an in-depth guide to aspartame here, which looks at the existing evidence from a wide range of studies.

Key Point: There is a lot of fearmongering and conspiracy theories about artificial sweeteners, but the evidence does not support many of the exaggerated claims about them.

16) “Breakfast Is the Most Important Meal of the Day” OR “We Should All Skip Breakfast”

On the one hand, it is easy to come across breakfast being described as the most important meal of the day. On the other hand, some people suggest that everyone would do better if they skipped breakfast.

However, what does the evidence say?

A systematic review and meta-analysis of randomized controlled trials published in the British Medical Journal found that (79):

  • Skipping breakfast did not lead to weight gain.
  • There was no evidence that participants consuming breakfast had more weight loss than participants not eating it.
  • Participants consuming breakfast tended to have a slightly higher calorie intake, raising concerns over whether recommending breakfast for weight loss is inappropriate.

However, another systematic review of 26 trials involving adolescents found that breakfast improved academic performance, cognitive performance, and general well-being (80).

There are also some studies suggesting breakfast consumption may improve blood glucose and insulin sensitivity compared to those who skip breakfast, particularly in individuals with type 1 or 2 diabetes (81, 82, 83, 84).

In other words: the existing evidence is a mixed bag.

The truth is that we are all different and living in different situations. Perhaps whether breakfast is “good” or “bad” depends on the person and their lifestyle?

Key Point: Breakfast may be important, but so is what works best for each individual.

17) Juice Detoxes and Detox Diets “Cleanse” the Body

Juice detoxes are popular on social media, but the claims that they “cleanse” our bodies are nothing more than a myth.

Not only are these “detoxes” expensive, but they can potentially cause harm too. The National Institutes of Health note that such detoxification programs are often falsely advertised and unsafe (85).

One potential harm from these diets is that people following a juice detox may ingest significant quantities of high-oxalate juices, such as spinach, over a prolonged period. As mentioned in the ‘antinutrient’ section of this article, excessive intakes of oxalate from juicing have the potential to cause kidney issues (40, 41).

Also, the human body already has sufficient ability to “detox” through the kidneys and liver, which help to clear toxins from the body.

If someone genuinely feels they have a health issue that needs “detoxing” they should speak to their doctor/medical team about it rather than follow the advice of social media influencers.

Key Point: Juice detoxes and detox diets are usually an expensive scam.

18) We Should Avoid Cholesterol-Rich Foods

For many years, public health advice suggested that we should tightly limit the amount of dietary cholesterol we consume. This advice was based on the theory that higher dietary cholesterol intake led to higher amounts of cholesterol in the blood.

The implication was that we should all limit our intake of cholesterol-rich foods like eggs and shrimp, and the American Heart Association thus recommended “no more than three eggs per week” in 1968 (86, 87).

However, in recent years research has uncovered that dietary cholesterol does not have a significant impact on blood cholesterol levels or cardiovascular risk for most people (88, 89).

This led to the 2015-2020 Dietary Guidelines for Americans omitting dietary cholesterol as a “nutrient of concern for overconsumption” for the first time (90).

Unfortunately, it is still possible to come across claims that we should avoid all sources of dietary cholesterol, particularly from enthusiastic diet advocates on social media.

Yet a recent science advisory from the American Heart Association is quite clear: dietary cholesterol is not a major issue for most people. Further, it is the overall dietary pattern rather than a specific dietary cholesterol intake target that matters most (89).

Key Point: For most people, dietary cholesterol is not a significant issue.

19) Meat Is “Bad” For You

Some people may choose to avoid meat due to vegetarianism or veganism, which is a perfectly acceptable reason not to eat it.

However, simply claiming that all meat is inherently “bad” for someone is not well-supported by the evidence.

Some observational studies indeed link high intakes of red meat to an increased risk of gastrointestinal cancers. However, these associations are only seen at intake levels above a certain threshold and may be influenced by other factors such as cooking method – particularly high-temperature cooking (91, 92, 93, 94).

Furthermore, these associations only appear consistently for red meat rather than poultry and fish (95, 96).

Of course, this does not mean that we should just ignore epidemiological evidence linking high red meat to gastrointestinal cancer. However, many different foods have both potential benefits and downsides that are often dose-dependent.

On the positive side, red meat is a nutrient-rich food that offers an excellent source of bioavailable protein, vitamins, and minerals. In this regard, cohort studies undertaken in the United States have demonstrated that red meat is a significant contributor to zinc, iron, and vitamin B12 status among a diverse range of population groups (97).

All in all, meat is a nutritious food that can contribute a lot of nutritional value to the average diet.

Key Point: Meat may have both positive and negative effects, some of which may depend on factors like cooking method. However, exaggerated claims that all meat is “bad” for us lack nuance.

Final Thoughts

Nutritional science is complicated, and things are often a shade of grey rather than black or white.

Despite this, there are many strong claims about different foods and nutrients, and knowing what to believe can be difficult. For this reason, it is always a good thing to do some further research of our own rather than blindly believing in a particular claim.

Also, when there are strong and opposing viewpoints, the truth often lies somewhere in the middle of the two.

The same applies to many of the ‘nutrition myths’ mentioned in this article too.

For more nutrition-related articles, see here.

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What Is the Best Diet For Me?

Dietary Fiber: What Is It and What Does It Do?

Is Fruit Fattening? A Review of This Common Claim

List of Foods With a High Oxalate Content

Is Counting Calories Necessary?

Is Aspartame Bad For You? An Evidence-Based Guide

18 of the Most Nutrient-Dense Foods in the World

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