Fact or fiction? Let's explore what people are saying about keto and whether or not it's true or false.
The ketogenic diet remains the most popular diet in the world. Given this growing attention, you would be forgiven for thinking that this is just another faddish diet that will soon fade into the background only to give way to the next new eating trend.
The reality is that the ketogenic diet has been around for over 100 years. It was first developed as a clinical treatment for uncontrolled epilepsy in the 1920s but, over the decades, has also been shown to have numerous health benefits including weight loss, improved blood sugar levels and insulin sensitivity, reduced inflammation, and oxidative stress as well as positive effects on mood, neurological function, cardiovascular health, and metabolic wellbeing (1).
Due to these benefits, the ketogenic diet is unlikely to disappear any time soon. Nevertheless, some have raised concerns about keto, questioning its benefits and doubting its suitability as an alternative to the typical Western diet.
Of course, given that the ketogenic diet turns many traditional nutritional guidelines and assumptions on their head, it’s no surprise that there is so much misinformation and impulsive scepticism.
Therefore, it’s worth examining the most common keto myths, looking at what the research shows and sorting fact from fiction.
Keto Myth #1 - Your Brain Needs Carbs
Considering the ketogenic diet was first developed as an effective therapy for epilepsy it is ironic that this should be one of the more common misconceptions.
Furthermore, given that improved mental clarity and focus are some of the most noted benefits, this would suggest that the brain seems to manage quite well on a low carbohydrate diet.
While conventional thinking has always held that glucose was the brain’s preferred energy source, there are a host of studies demonstrating that ketones, which are produced during a ketogenic diet, are an efficient alternative fuel for the brain. In fact, compared to glucose, ketones are more efficient, providing more energy per unit of oxygen used (2).
Ketones are also a cleaner energy source because they produce fewer toxic byproducts of metabolism, such as reactive oxygen species, which can cause inflammation and cell damage and increase the risk of neurodegenerative diseases (3).
It is worth noting that most neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease, are characterised by disturbances in glucose metabolism which may be involved in both disease development and progression (4). This, in part, explains why a ketogenic diet is being considered and researched as a treatment for these conditions (5).
It may also account for the evidence from studies that reported positive effects of ketones on cognitive function (6).
The ketogenic diet has also been demonstrated to have mood stabilising benefits by regulating the levels and functions of neurotransmitters, such as dopamine, serotonin, GABA, and glutamine (7).
Keto Myth #2 - It's bad for heart health and will raise your cholesterol
A keto diet involves consuming more fat and cholesterol than a typical carbohydrate-based diet rich in grains. As a result, it has raised some concerns that it can elevate blood cholesterol levels and increase the risk for cardiovascular disease.
These fears are founded on a flawed hypothesis first proposed by nutritionist Ancel Keys in the early 1950s. He theorised that people who consumed high amounts of saturated fat had elevated levels of cholesterol leading to higher rates of death from heart disease.
Yet, despite the investment of billions of dollars into the fat hypothesis and the comprehensive promotion of low-fat diets around the world, the rate of deaths due to coronary artery disease is increasing (8).
What the research shows is that saturated fat has little to no influence on serum cholesterol levels and is not significantly associated with the development of stroke or heart disease. (9, 10).
In fact, the evidence is all pointing towards our carbohydrate consumption. A recent large-scale study involving 148,858 participants across 21 countries concluded that a high intake of refined grains and carbohydrates was associated with a higher risk of mortality and major cardiovascular disease events. The authors recommended that lower consumption of refined grains and carbohydrates should be considered, globally (11).
So, what does the research say about the ketogenic diet?
One study looking at a total of 447 individuals found that it was not only effective for weight loss but also improved triglyceride and cholesterol values (12).
Another meta-analysis found that low-carbohydrate diets lead to a significant decrease in both systolic and diastolic blood pressure, triglyceride levels, an increase in HDL cholesterol levels (good), and no change in LDL cholesterol levels (13).
A third meta-analysis drawing on 25 studies found that individuals assigned to a low-carb ketogenic diet also achieved greater reductions in body weight, triglycerides, and blood pressure, but they also demonstrated a greater increase in HDL (good) and LDL cholesterol (14).
For most people, a ketogenic diet causes no adverse effects on blood markers with results typically showing stable LDL cholesterol levels, a decrease in triglycerides, and an increased HDL cholesterol (15, 16).
If you have a genetic predisposition or a history of elevated cholesterol levels or heart issues, we advise undertaking a ketogenic diet with the supervision of your doctor.
Keto Myth #3 - Keto is dangerous long-term
Critics of the ketogenic diet often claim that because there are no studies examining the long-term safety of a ketogenic diet, it is irresponsible and potentially dangerous to stick with this diet for an extended period of time.
It is true to say that there are no long-term studies looking at the wider health parameters associated with a ketogenic diet over several years or decades, but the same is true for every other diet including the DASH diet, Mediterranean diet, Flexitarian diet, Plant-based diet, MIND diet, vegetarian and vegan diets. In fact, no diet on the planet has been proven safe for long-term consumption by a study.
Nevertheless, as the body of research examining the near-term health benefits of a ketogenic diet grows, it becomes harder and harder to imagine that this poses any of the potential long-term risks touted by concerned critics. Dozens of studies have demonstrated that ketogenic diets are associated with wide and profound health benefits including a reduction in body weight and body mass index, improved cardiovascular risk factors including blood pressure, the reversal of type 2 diabetes, improved acne, reduced risk of certain cancers, improved PCOS symptoms, reduced inflammation, and improved brain function (17).
Given these health improvements, how exactly do keto-sceptics propose that a ketogenic diet is potentially dangerous?
Keto Myth #4 - Keto may cause fatty liver
Fatty liver is a serious condition associated with liver damage, type 2 diabetes, high blood pressure and kidney disease. It was once a rare condition almost exclusively associated with alcoholism but is now all too common. Today, non-alcoholic fatty liver disease (NAFLD) is becoming the most common cause of chronic liver disease in the developing world, found in 17-30% of the population in Western countries (18).
Several factors have been shown to contribute to the development of NAFLD, including the consumption of excess calories, eating too many refined carbohydrates and sugars as well as a sedentary lifestyle.
Overeating saturated fat has also been shown to increase the likelihood of developing NAFLD, but these studies typically identify saturated fat as a source of excess calories in a diet already high in carbohydrates (19).
Due to the association of NAFLD with obesity, the typical dietary recommendations are based on the conventional notion that eating a low-fat diet will lead to weight loss and therefore improve fatty liver.
However, the evidence indicates that low-carb diets are more effective than low-fat diets at treating fatty liver (20).
A recent study concluded that a ketogenic diet is an effective treatment for nonalcoholic fatty liver disease and markedly decreased liver fat content and hepatic insulin resistance (21).
Of course, this makes perfect sense when we consider that ketosis promotes the conversion of fats to ketones to be used as fuel by the body.
Keto Myth #5 - Keto causes kidney stones
There is some evidence that following a highly restrictive medical ketogenic diet for a condition like epilepsy may increase the risk of kidney stones (22).
For those following a more moderate ketogenic diet, these risks are far less likely. Nevertheless, there are anecdotal accounts of ketogenic diets causing kidney stones.
Keeping in mind that kidney stones are extremely common, with up to eight per cent of Australians experiencing them at some time, there are some contributing factors that could increase the risk of kidney stones while on a keto diet. These include not drinking enough water, not replacing your electrolytes, and eating too many vegetables high in oxalates
There has been some concern that higher levels of protein consumption increase the risk of kidney stones, but there is no significant evidence for this in healthy individuals (23). Besides, a ketogenic diet involves the consumption of moderate amounts of protein, not high or excessive amounts.
Understanding these factors means there are some simple measures you can take to minimise any risk. These factors are typically most apparent when you first start a ketogenic diet. During the early stages of ketosis, your kidneys release stored water from muscles. This can result in dehydration and loss of electrolytes which may last for the first one or two weeks until the body has properly adapted to ketosis.
The best way to approach this issue is to treat it as if you were doing regular exercise and ensure you stay hydrated and replace lost electrolytes.
Keto Myth #5 - May cause gall bladder problems
The gallbladder is a small, pear-shaped organ that sits just beneath your liver. Its role is to store bile produced in the liver and then release it into the small intestine to help with the breakdown of fat.
Gallstones may form in some people when bile stored in the gallbladder hardens into a stone-like material. Most people who have gallstones don't know it but when gallstones become larger, or when they begin obstructing bile ducts, symptoms or ‘attacks’ may occur.
Conventional medical thinking assumes that eating fatty foods can result in the formation of gallstones and cause gallbladder attacks. Therefore, a low-fat diet is typically recommended. The problem with such advice is that when we eat a low-fat diet the flow of bile is reduced resulting in longer bile storage time which increases the risk of gallstone formation.
In fact, several studies have demonstrated that low-fat diets significantly increase your risk of developing gallstones (24, 25). One such study observed that a relatively high fat intake could prevent gallstone formation, probably by maintaining adequate gallbladder emptying (26).
Another study found that a high intake of carbohydrates increases the risk of gallstone disease. The researchers concluded that these results add to the concern that low-fat, high-carbohydrate diets may not be an optimal dietary recommendation (27).
One word of caution is if you have existing gallstones, eating fat may initially lead to some gallstone pain. In such a case you may need to introduce a ketogenic diet slowly and do so under the consultation of a qualified healthcare professional.
Nevertheless, based on the evidence, a ketogenic diet supports gallbladder health and prevents the formation of gallstones.
Keto Myth #6 - Potential for vitamin and mineral deficiency
An examination of the standard Western diet will quickly reveal one that is characterised by refined carbohydrates, simple sugars, and processed foods. These are otherwise known as empty calories as they provide little nutritional value other than a quick hit of energy.
The bread and pasta that feature so heavily in our modern diet are made from refined flour that has been stripped of any nutrition that may have originally existed in the grains they came from. And, while wholegrain wheat may contain more nutrients than its processed counterpart, it is also a rich source of phytates that can block the absorption of many nutrients.
The fruit we eat is bred for sweetness and not nutrition.
And, the low-fat milk, yoghurt, cheese and even cream that have been consistently recommended over the last 50 years are also low in essential fat-soluble vitamins, such as vitamins A, E and D.
Now, let's compare that diet to a low-carb, high-fat ketogenic diet rich in nutritious fats such as avocado, olive oil, flaxseed oil, grass-fed butter, and fatty fish rich in omega 3s. Also, a ketogenic diet typically includes plenty of eggs (a power-packed source of nutrition) and recommends nutrient-dense protein foods including fish, seafood, grass-fed meat, and organ meats. And don’t forget to include plenty of low-carb, fibrous green-leafy veggies and some healthy nuts and seeds.
In support of this approach, a recent study assessing the nutrient intake of a low-carb, high-fat diet found that a well-planned keto meal plan can be considered replete in micronutrients. The authors went on to say that this is an important finding for health professionals, consumers, and critics of keto nutrition, as it dispels the myth that these diets are suboptimal in their micronutrient supply (28).
Keto Myth #7 - Keto is not good for your gut
A common criticism of the ketogenic diet is that because it removes high-carb foods like fruit, starchy vegetables, grains, and legumes it also eliminates important sources of dietary fibre.
A vast body of scientific evidence has accumulated on the association of dietary fibre with digestive health, regular bowel movements, satiety, improved cholesterol, and blood sugar levels, assisting with the prevention of diseases such as diabetes, heart disease and bowel cancer and promoting a healthy gut microbiome.
The concern that a ketogenic diet can be low in dietary fibre is not necessarily unjustified. It is not unusual for people to overlook the inclusion of high fibre foods when cutting out high-carb sources, which can result in constipation, poor digestion and an adversely affected gut microbiome.
However, if you have a well-planned ketogenic diet, not only will you be getting enough fibre, but it is likely to contain more fibre than most other diets. There are plenty of low-carb, high-fibre foods to choose from including all leafy green vegetables and cruciferous vegetables such as broccoli, cauliflower, Brussel sprouts, cabbage, and kale. Keto-friendly fruits such as avocado and low-sugar berries are excellent sources of fibre as well as antioxidants and phytonutrients.
And then there are nuts and seeds including Chia seeds, flaxseeds, hemp seeds, almonds and walnuts.
So, how else might a ketogenic diet affect our gut health?
One recent study showed that after 8 weeks on a ketogenic diet positive changes in the gut microbiome were driven by ketones that led to reduced levels of pro-inflammatory Th17 cells (29).
Keto Myth #8 - People just can’t stick with keto
When all of the concerns have been addressed the last remaining issue people often have with a ketogenic is that it is just too restrictive, and people can’t stay with it long-term.
There is little argument that the ketogenic diet differs from the more familiar standard Western diet, if properly planned a ketogenic diet can be a diverse, delicious, and satisfying eating plan.
The fact that people can still eat as much as they like as long as they reduce their carbohydrate intake also enhances its appeal.
Furthermore, a ketogenic diet tends to be very sustainable, especially once people enter ketosis. Many people note being able to go for long periods of time without eating because they no longer feel hungry between meals.
A study from 2017 examined how 1580 voluntary adherents to a low-carbohydrate diet rated its effectiveness and sustainability. The majority of respondents had consumed less than 100 g of carbohydrates per day for over a year and reported numerous health benefits including weight loss and improved blood glucose and lipids. They also noted a reduction in medication use, especially pain relievers and anti-inflammatories, with an average monthly saving of $288.
The researchers concluded that low-carbohydrate diets are a sustainable method of metabolic syndrome reversal in a community setting (30).
Another study involving patients with Type 2 diabetes showed an impressive 84% adherence to a ketogenic diet after 1 year (31).
There will always be pushback and scepticism whenever orthodox ideas and methods are challenged. This is healthy and compels adherents of new ideas to support their claims with evidence and good reasoning.
A ketogenic diet is an approach to eating that certainly turns traditional thinking about what a healthy, balanced diet looks like upside down. In many ways, it contradicts firmly held beliefs that have formed the cornerstone of dietary advice for over half a century.
Nevertheless, the evidence has been mounting steadily over recent years that low-carb, high-fat diets are healthy and effective strategies for improving many of the factors associated with some of the most common and serious chronic diseases.
It almost makes you wonder if our ancestors ate this way.
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