6th July, 2022 updated 20th July, 2022

Nutrition myths

There are way too many things I hear people say that make me wince and cringe. When I ask them why they believe those things they assert, most of the times they say somebody said so. These people are just repeating what they heard. Most of these things are not supported by the scientific literature, some of them are supported by misunderstandings or misrepresentations of the scientific literature and a few of these are supported by cherry picking flawed articles published on obscure journals. These are myths. They're everywhere, and I wish I wouldn't have to hear them wherever I go.

This blog post will be updated frequently and new myths will be discussed periodically. The objective of this post is to allow me to simply link this page to my customers and friends, so that I do not have to repeat myself over and over again.

Calories don't count

Calories in - calories out is another way to refer to the concept of energy balance. This concept is illustrated by the energy balance equation: gross energy value of food = total daily energy expenditure (TDEE). The TDEE is composed by all of the methods with which a person expends energy during the day, including thermic effect of food, resting metabolism and physical activity (McArdle et al., 2012) .

This equation has never been observed to have been defied, and defying such basic equation would mean to defying the laws of thermodynamics. Despite that, a lot of people claim that this equation does not always hold true, that a calorie is not a calorie. The reason these people dispute the energy balance equation is because of misunderstandings, either of the equation itself or of the tools they rely on to measure their energy expenditure.

Common errors are caused by the estimated energy value of food consumed and the estimation of energy expended with exercise. Accessories that track the activity such as the Fitbit estimate very inaccurately the energy expenditure and should not be used to reach the absurd conclusion that one's body is defying the laws of physics.

The variables in the equation are not independent, but interdependent: when gross energy value of food is increased, the TDEE increases in response, and when a person eats less then TDEE decreases in response. This does not mean that changing calorie intake is pointless, but it does have an effect on TDEE.

In my experience, some individuals require small changes in their calorie intake to lose weight and their behavior is barely unaffected, while some others require a larger change in calorie intake to achieve a clorie deficit and weight loss, the behavior of these individuals can be observed to change significantly.

Artificial sweeteners are evil

There are a lot of claims regarding the effects and the safety of artificial sweeteners. Aspartame was one of the first artificial sweeteners to be suspected to cause cancer and other diseases. This suspicion was also extended to all of the artificial sweeteners. This suspicion was unfounded, aspartame has been studied extensively and has never been proven to be unsafe (Butchko et al., 2002) .

More recently artificial sweeteners have been suggested to cause the body to behave in abnormal and undesireable ways, particularly when it comes to weight control. Many of these claims are connected to the carbohydrate-insulin hypothesis and conclude that artificial sweeteners cause the body to accumulate fat. This is in opposition to the evidence which instead consistently shows that replacing sugar-sweetend drinks with artificially-sweetened drinks is more effective as a weight loss intervention than replacing sugar-sweetened drinks with water (McGlynn et al., 2022) .

While water may be better than artificially-sweetened drinks, some people who consume sugar-sweetened drinks are unable to switch from their usual drinks to plain water. For those people, artificially-sweetend drinks are the best option to limit their food intake and to help them control their weight. Artificially-sweetened drinks do not show any negative effects and there is no reason to avoid them, other than cost, which is higher than water (in most locations).

Gluten-free diets are healthier

Gluten is a protein found in many grains, including wheat. Wheat is the main ingredient of pasta, bread, cookies, cakes, etc. All of these foods are super tasty, and as usual, some people are ready to scare you away from eating them.

About 1% of the population (Mustalahti et al., 2010) suffers from celiac disease, a disease that causes damage to the intestinal villi when gluten comes into contact with them. These people are treated by removing gluten from their diet, this treatment seems to reverse the damage they experienced. But some people claim that everybody should avoid gluten, that celiac disease is just an extreme case of what we all have when we eat gluten. This claim does is not supported by the evidence.

Non-celiac gluten sensitivity, also referred to as gluten sensitive enteropathy or gluten intolerance, is an intolerance to gluten with similar symptoms as seen with celiac disease, but without the accompanying elevated levels of antibodies and intestinal damage. The problem is that there is no convincing evidence that this condition actually exists. There is no way to diagnose it, because there is substancial doubt that it is real.

There is also concrete evidence that consuming a gluten-free diet can have negative effects. In a study involving over 100,000 participants without celiac disease, suggested that non-celiac individuals who avoid gluten may increase their risk of heart disease, due to the potential for reduced consumption of whole grains, sources of vegetable fibers, vitamins and minerals. (Lebwohl et al., 2017)

Gluten may also act as a prebiotic. Bacteria like Arabinoxylan oligosaccharide, which are normally found in a healthy human gut, can cause gastrointestinal diseases when their activity is impacted by such drastic dietary choices (Neyrinck et al., 2012) .

Some evidence shows that people with celiac disease have a slightly higher risk of developing cognitive impairment, one of the symptoms of this impairment is often referred to as brain fog. A study involving about 13,000 women without celiac disease were followed for 28 years to observe any potential links between gluten intake and cognitive function. No significant differences were found in cognitive scores comparing women with the highest and lowest gluten intakes. Even accounting for those who developed dementia or cancer in the course of the study (Wang et al., 2021) .

Gluten is a source of problems only for those who test positive for celiac disease. Most people can and have eaten gluten for their entire lives, without any adverse side effects.

Protein will kill you

Protein has been associated with many myths, in particular it is said to cause several diseases. One that is way too common to hear is that excess protein causes kidney diseases. Long ago it was thought that the nitrogen contained in proteins would have to be eliminated with urea and that this process would cause kidney failure. There is no evidence that excess protein harms healthy kidneys, more than 20 years ago the consensus was already established in that a low-protein diet may even be the cause of kidney function decline (Institute of Medicine, 1999) and more recently, it was again stated that the claim has no foundation and instead is directly opposed to the evidence which suggests that an increase of protein in the diet is correlated to improvements in kidney function (Phillips et al., 2016) .

Similarly, protein has been suggested by many individuals to cause liver disease. Their idea is that because aminoacids are processed by the liver, then an excess of aminoacids can damage the liver. Once again there is no evidence to support this claim.

Heart disease has been associated with protein consumption because people who consume a lot of meat, particularly in the united states of america, often consume cuts of red meat rich in saturated fatty acids, and are also often overweight and obese. While a diet rich in saturated fatty acids and being overweight and obese are factors associated with heart disease, there is no evidence to support that protein itself causes heart disease. The mediterranean diet, which is categorized as high-protein diet, has also been found so heart-healthy that it is prescribed to individuals who have had myocardial infarction (McArdle et al., 2012) .

Protein has also been said to cause bone mineral density loss and, by extensions, osteopenia and osteoporosis. This can scare women in particular as they are the population most affected by these diseases (McArdle et al., 2012) .

This myth dates back to the 1920's when increased protein in the diet had been observed to cause an increase in calcium excretion with no change in total calcium absorption by the intestine. This lead to the formulation of the acid-ash hypothesis: eating more protein would lower the pH of the fluids in the body, leading to the erosion of bones. This hypothesis has since been shown to be wrong several times: first the assumption that calcium absorption was unaffected by the change in diet was wrong, secondly the mechanism can't be happen because of the several buffer systems that keep the pH of blood and other fluids stable. Futher, markers of calcium metabolism do not correlate with calcium excretion, and individuals consuming extremely high-protein diets do not show symptoms of osteoporosis (Fenton et al., 2009) .

Despite the evidence, the acid-ash hypothesis has been utilized as the basis of several different myths, some claiming that the body can be in an acidosis state and that one must strive to eat a specific alkaline diet to cure all kind of diseases, including obesity. Of course, all of these claims are nonsense.

Fasting is magic

Fasting is the practice of not eating any food except for drinking water. There are several different relatively common approaches to fasting and all of these approaches have their own unique claims.

Intermittent fasting is the practice of limiting food intake within a time window during each day. For example one could decide not to eat any food before 10:00 and after 16:00 for months or even years. This dietary choice "is not more effective in weight loss than eating throughout the day" (Lowe et al., 2020) .

A common claim is that intermittent fasting grants psychological benefits but this is not backed by any scientific evidence. Another common claim is that this dietary choice improves body composition by increasing lean body mass more than conventional time-unrestricted feeding: this claim is in contradiction with the scientific evidence in many ways. Evenly spreading protein in at least 3 meals during the day (Mamerow et al., 2014) and supplementating with protein right before night sleep (Snijders et al., 2019) are currently thought as the most optimal ways to maintain or increase lean body mass.

Alternate day fasting is a self-explanatory name. This dieting practice also does not seem to have any benefit and all the supposed benefits on body composition and health are attributable to the weight loss that may occur if the fasting leads to a calorie restriction. (Trepanowski et al., 2017) .

Additionally, if a calorie restriction is obtained with this approach, it is clear that the weight loss will be at the expense of lean body mass, which is instead maintained with a conventional daily calorie restriction approach (Templeman et al., 2021) . This is likely because the human body does not have a mechanism to store aminoacids which, if not provided frequently enough, will be obtained by breaking down lean body mass. The loss of lean body mass is to be avoided in general but it is particularly dangerous to older individuals who already lose lean body mass due to the ageing process.

Another thing worth nothing about alternate day fasting is that there is a mesurable and significant decrease in TDEE, which means that it is very likely for mood, non-exercise activity thermogenesis (NEAT) and other components of TDEE to be negatively affected by this practice (Templeman et al., 2021) .

Inflammation must be avoided

Inflammation sounds like something one should avoid at all costs, that is because everybody has taken, at least once, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen. Most women take these drugs to soothe the pain of the menstrual cycle. However, there are some kinds of inflammation that are desireable, such as the acute response to strength training: the use of NSAIDs to reduce this kind of inflammation has been shown to reduce strength training adaptations (Lilja et al., 2017) .

It is important to understand that not all sorts of inflammation are the same. Chronic systemic inflammation can contribute to the development of heart disease and cancer. Strength training, which causes acute localized inflammation, instead offers protection against heart disease and cancer (among other benefits). Chronic vs acute and systemic vs localized are important differences, unfortunately even some allegedly highly educated people do not understand.

Some groups claim that their diet is superior to other diets because of the way it supposedly modulates chronic systemic inflammation. Any diet, whether it is high-fat, high-carb or high-protein, reduces systemic inflammation as long as it introduces a calorie deficit (Kovell et al., 2020) . In particular, there is no evidence that sugar is inflammatory when calories are equated. (Sørensen et al., 2005) .

There is some evidence suggesting that replacing saturated fat sources with omega-3 fatty acids lowers systemic inflammation (Mazidi et al., 2017) , this benefit seems to be helpful in reducing the effect of systemic lupus erythematosus (Duarte-García et al., 2020) but this does not mean that omega-3 supplementation is beneficial to improve other conditions or even general health.

To date, there is no evidence that an optimal ratio between omega-3 and omega-6 exists, and there is no evidence that it should even be a concern. There are many mechanistic studies but no human randomized control trial to investicate these claims. Both omega-3 and omega-6 are essential fatty acids: humans need a certain amount for function, but excess of any of these fatty acids does not seem to cause any harm (except when this excess causes weight gain which in turn causes harm).

You need to detox

There are a lot of claims about toxins. One such claim is that the body being in a state of toxicity, and that removing toxins causes the removal of fat cells which store these toxins. This is nonsense. there is no evidence that the body creates more fat cells to store toxins, and even if that was the case, there are further nonsense assumptions: there is no evidence that any treatment can remove physiological toxins from the body and there also is no evidence that if those were removed then fat cells would also be removed.

Toxin is a buzzword that is thrown around frequently, but which toxins are being discussed is never explicit. Likely because the people who talk about toxins do not know themselves what toxins are and the audience does not know and/or does not care.

Let's entertain the idea that these toxins that are being talked about are in fact real. If we assume that people eat a constant amount of food but toxins cause them to have a harder time losing weight, then these toxins must affect the TDEE. In clinical acute toxicity reports, such as renal and liver failure, the TDEE occasionally remains the same but most of the times it actually increases. This is because the body produces proteins used to remove these excess toxins, and such processes requires energy and matter. Therefore toxicity should promote weight loss, not inhibit it.