Mainstream nutrition is full of nonsense.
Despite clear advancements in nutrition science, the old myths don't seem to be going anywhere.
Here are 20 mainstream nutrition myths that have been debunked by scientific research.
Several decades ago, the entire population was advised to eat a low-fat, high-carb diet ().
At the time, not a single study had demonstrated that this diet could actually prevent disease.
Since then, many high quality studies have been done, including the Women's Health Initiative, which is the largest nutrition study in history.
Bottom Line: Numerous studies have been done on the low-fat, high-carb diet. It has virtually no effect on body weight or disease risk over the long term.
The salt myth is still alive and kicking, even though there has never been any good scientific support for it.
Although lowering salt can reduce blood pressure by 1-5 mm/Hg on average, it doesn't have any effect on heart attacks, strokes or death (, ).
Of course, if you have a medical condition like salt-sensitive hypertension then you may be an exception (8).
But the public health advice that everyone should lower their salt intake (and have to eat boring, tasteless food) is not based on evidence.
Bottom Line: Despite modestly lowering blood pressure, reducing salt/sodium does not reduce the risk of heart attacks, strokes or death.
It is often claimed that people should eat many, small meals throughout the day to keep the metabolism high.
But the studies clearly disagree with this. Eating 2-3 meals per day has the exact same effect on total calories burned as eating 5-6 (or more) smaller meals (, ).
Eating frequently may have benefits for some people (like preventing excessive hunger), but it is incorrect that this affects the amount of calories we burn.
There are even studies showing that eating too often can be harmful... a new study came out recently showing that more frequent meals dramatically increased liver and abdominal fat on a high calorie diet (11).
Bottom Line: It is not true that eating many, smaller meals leads to an increase in the amount of calories burned throughout the day. Frequent meals may even increase the accumulation of unhealthy belly and liver fat.
We've been advised to cut back on whole eggs because the yolks are high in cholesterol.
However, cholesterol in the diet has remarkably little effect on cholesterol in the blood, at least for the majority of people (, 13).
Studies have shown that eggs raise the "good" choleserol and don't raise risk of heart disease ().
One review of 17 studies with a total of 263,938 participants showed that eating eggs had no effect on the risk of heart disease or stroke in non-diabetic individuals ().
However... keep in mind that some studies have found an increased heart attack risk in diabetics who eat eggs (16).
Whole eggs really are among the most nutritious foods on the planet and almost all the nutrients are found in the yolks.
Telling people to throw the yolks away may just be the most ridiculous advice in the history of nutrition.
Bottom Line: Despite eggs being high in cholesterol, they do not raise blood cholesterol or increase heart disease risk for the majority of people.
Wheat has been a part of the diet for a very long time, but it changed due to genetic tampering in the 1960s.
The "new" wheat is significantly less nutritious than the older varieties ().
Preliminary studies have shown that, compared to older wheat, modern wheat may increase cholesterol levels and inflammatory markers (, 19).
It also causes symptoms like pain, bloating, tiredness and reduced quality of life in patients with irritable bowel syndrome ().
Whereas some of the older varieties like Einkorn and Kamut may be relatively healthy, modern wheat is not.
Also, let's not forget that the "whole grain" label is a joke... these grains have usually been pulverized into very fine flour, so they have similar metabolic effects as refined grains.
Bottom Line: The wheat most people are eating today is unhealthy. It is less nutritious and may increase cholesterol levels and inflammatory markers.
For decades, we've been told that saturated fat raises cholesterol and causes heart disease.
In fact, this belief is the cornerstone of modern dietary guidelines.
For most people, eating reasonable amounts of saturated fat is perfectly safe and downright healthy.
Bottom Line: Several recent studies have shown that saturated fat consumption does not increase the risk of death from heart disease or stroke.
Coffee has long been considered unhealthy, mainly because of the caffeine. However, most of the studies actually show that coffee has powerful health benefits.
Coffee drinkers have a much lower risk of depression, type 2 diabetes, Alzheimer's, Parkinson's... and some studies even show that they live longer than people who don't drink coffee (30, 31, 32, 33, 34).
Bottom Line: Despite being perceived as unhealthy, coffee is actually loaded with antioxidants. Numerous studies show that coffee drinkers live longer and have a lower risk of many serious diseases.
Fat is the stuff that is under our skin, making us look soft and puffy.
Therefore it seems logical that eating fat would give us even more of it.
However, this depends entirely on the context. Diets that are high in fat AND carbs can make you fat, but it's not because of the fat.
Bottom Line: The fattening effects of dietary fat depend entirely on the context. A diet that is high in fat but low in carbs leads to more weight loss than a low-fat diet.
It is often said that dietary protein increases strain on the kidneys and raises the risk of kidney failure.
Although it is true that people with established kidney disease should cut back on protein, this is absolutely not true of otherwise healthy people.
In fact, a higher protein intake lowers blood pressure and helps fight type 2 diabetes... which are two of the main risk factors for kidney failure (, ).
Also let's not forget that protein reduces appetite and supports weight loss, but obesity is another strong risk factor for kidney failure (, 44).
Bottom Line: Eating a lot of protein has no adverse effects on kidney function in otherwise healthy people and improves numerous risk factors.
High-fat dairy products are among the richest sources of saturated fat in the diet and very high in calories.
For this reason, we've been told to eat low-fat dairy products instead.
However, the studies do not support this. Eating full-fat dairy product is not linked to increased heart disease and is even associated with a lower risk of obesity (45).
In countries where cows are grass-fed, eating full-fat dairy is actually associated with up to a 69% lower risk of heart disease (, ).
If anything, the main benefits of dairy are due to the fatty components. Therefore, choosing low-fat dairy products is a terrible idea.
Of course... this does not mean that you should go overboard and pour massive amounts of butter in your coffee, but it does imply that reasonable amounts of full-fat dairy from grass-fed cows are both safe and healthy.
Bottom Line: Despite being high in saturated fat and calories, studies show that full-fat dairy is linked to a reduced risk of obesity. In countries where cows are grass-fed, full-fat dairy is linked to reduced heart disease.
It is simply false that "all calories are created equal." Different foods go through different metabolic pathways and have direct effects on fat burning and the hormones and brain centers that regulate appetite (48, , 50).
A high protein diet, for example, can increase the metabolic rate by 80 to 100 calories per day and significantly reduce appetite (, , ).
In one study, such a diet made people automatically eat 441 fewer calories per day. They also lost 11 pounds in 12 weeks, just by adding protein to their diet ().
There are many more examples of different foods having vastly different effects on hunger, hormones and health. Because a calorie is not a calorie.
Bottom Line: Not all calories are created equal, because different foods and macronutrients go through different metabolic pathways. They have varying effects on hunger, hormones and health.
When the low-fat guidelines first came out, the food manufacturers responded with all sorts of low-fat "health foods." The problem is... these foods taste horrible when the fat is removed, so the food manufacturers added a whole bunch of sugar instead.
The truth is, excess sugar is incredibly harmful, while the fat naturally present in food is not (, ).
Bottom Line: Processed low-fat foods tend to be very high in sugar, which is very unhealthy compared to the fat that is naturally present in foods.
We are constantly warned about the "dangers" of eating red meat.
It is true that some studies have shown negative effects, but they were usually lumping processed and unprocessed meat together.
The largest studies (one with over 1 million people, the other with over 400 thousand) show that unprocessed red meat is not linked to increased heart disease or type 2 diabetes (, ).
Two review studies have also shown that the link to cancer is not as strong as some people would have you believe. The association is weak in men and nonexistent in women (, ).
So... don't be afraid of eating meat. Just make sure to eat unprocessed meat and don't overcook it, because eating too much burnt meat may be harmful.
Bottom Line: It is a myth that eating unprocessed red meat raises the risk of heart disease and diabetes. The cancer link is also exaggerated, the largest studies find only a weak effect in men and no effect in women.
It is often claimed that no one benefits from a gluten-free diet except patients with celiac disease. This is the most severe form of gluten intolerance, affecting under 1% of people (, ).
But another condition called gluten sensitivity is much more common and may affect about 6-8% of people, although there are no good statistics available yet (, ).
However... people should eat foods that are naturally gluten free (like plants and animals), not gluten-free "products." Gluten-free junk food is still junk food.
But keep in mind that the gluten situation is actually quite complicated and there are no clear answers yet. Some new studies suggest that it may be other compounds in wheat that cause some of the digestive problems, not the gluten itself.
Bottom Line: Studies have shown that many people can benefit from a gluten-free diet, not just patients with celiac disease.
Weight loss (and gain) is often assumed to be all about willpower and "calories in vs calories out." But this is completely inaccurate.
The human body is a highly complex biological system with many hormones and brain centers that regulate when, what and how much we eat.
It is well known that genetics, hormones and various external factors have a huge impact on body weight ().
Although it is still the individual's responsiblity to do something about their weight problem, blaming obesity on some sort of moral failure is unhelpful and inaccurate.
Bottom Line: It is a myth that weight gain is caused by some sort of moral failure. Genetics, hormones and all sorts of external factors have a huge effect.
The mainstream health organizations often lump saturated and artificial trans fats in the same category... calling them the "bad" fats.
However, saturated fat is harmless, so it makes absolutely no sense to group the two together.
Interestingly, these same organizations also advise us to eat vegetable oils like soybean and canola oils.
But these oils are actually loaded with unhealthy fats... one study found that 0.56-4.2% of the fatty acids in them are toxic trans fats (75)!
Bottom Line: Many mainstream health organizations lump trans fats and saturated fats together, which makes no sense. Trans fats are harmful, saturated fats are not.
It is commonly believed that eating protein raises the acidity of the blood and leaches calcium from the bones, leading to osteoporosis.
Although it is true that a high protein intake increases calcium excretion in the short-term, this effect does not persist in the long-term.
The truth is that a high protein intake is linked to a massively reduced risk of osteoporosis and fractures in old age (, , 78).
This is one example of where blindly following the conventional nutritional wisdom will have the exact opposite effect of what was intended!
Bottom Line: Numerous studies have shown that eating more (not less) protein is linked to a reduced risk of osteoporosis and fractures.
Low-carb diets have been popular for many decades now.
Mainstream nutrition professionals have constantly warned us that these diets will end up clogging our arteries.
However, since the year 2002, over 20 studies have been conducted on the low-carb diet.
Low-carb diets actually cause more weight loss and improve most risk factors for heart disease more than the low-fat diet (79, ).
Although the tide is slowly turning, many "experts" still claim that such diets are dangerous, then continue to promote the failed low-fat dogma that science has shown to be utterly useless.
Of course, low-carb diets are not for everyone, but it is very clear that they can have major benefits for people with obesity, type 2 diabetes and metabolic syndrome... some of the biggest health problems in the world (81, 82, 83, ).
Bottom Line: Despite having been demonized in the past, many new studies have shown that low-carb diets are much healthier than the low-fat diet still recommended by the mainstream.
Pretty much everyone agrees that sugar is unhealthy when consumed in excess.
But many people still believe that it is only bad because it supplies empty calories.
Well... nothing could be farther from the truth.
When consumed in excess, sugar can cause severe metabolic problems (, ).
Although sugar is fine in small amounts (especially for those who are physically active and metabolically healthy), it can be a complete disaster when consumed in excess.
Vegetable oils like soybean and corn oils are high in Omega-6 polyunsaturated fats, which have been shown to lower cholesterol levels.
But it's important to remember that cholesterol is a risk factor for heart disease, not a disease in itself.
Just because something improves a risk factor, it doesn't mean that it will affect hard end points like heart attacks or death... which is what really counts.
The truth is that several studies have shown that these oils increase the risk of death, from both heart disease and cancer (, , 93).
Even though these oils have been shown to cause heart disease and kill people, the mainstream health organizations are still telling us to eat them.
They just don't get it... when we replace real foods with processed fake foods, we become fat and sick.
How many decades of "research" does it take to figure that out?