8 Myths of the Ketogenic Diet: What Science Really Says

The ketogenic diet limits carbohydrate intake. It’s a high-fat diet with moderate protein. The diet consists of 80-90% fat, 6-15% protein, and 5-10% carbohydrates. 

Our primary energy source is glucose, which we get from carbohydrates. When you consume only small amounts of carbohydrates, your body enters a state called ketosis, transforming fat into ketones to be used as an alternative energy source.

Some studies support the benefits of the ketogenic diet, including blood glucose management and weight loss. Despite this, there is a lot of misinformation about the ketogenic diet on the Internet. We will examine the top keto myths and discuss the truth behind them.

Myth 1: Keto Is a Fad Diet

While some people have no doubts that keto is the best diet, others may think it's just a fad. The ketogenic diet is not a fad diet. In fact, it has been used as part of the treatment for people with epilepsy.¹ 

However, it has recently gained popularity due to its effects on weight loss and metabolism. Further research is needed to fully understand the long-term effects of keto on health, its safety and efficacy, and how it works in people with different conditions.

Myth 2: Going Keto Is The Fastest And Best Way To Lose Weight

Research shows that the ketogenic diet can help with weight loss, but it is not necessarily faster or more effective than a calorie-deficit diet combined with regular exercise. 

A recent study showed that after three months on a ketogenic diet, participants who were overweight lost an average of 4.6 kg.² In another study, researchers looked at how a calorie-restricted diet affected weight loss in women with obesity. In one month, participants lost an average of 3.9 kg.³ Therefore, no conclusive evidence shows that keto is faster or more effective. The results can change based on many individual factors. 

Myth 3: Keto Feels Amazing

When first starting keto, it's likely to experience symptoms due to drastic changes in the diet.

Decreased carbohydrate intake can cause symptoms that may last for a few days to weeks with varying intensities.¹⁻⁴ But they are expected to disappear as the body adapts to the diet. These symptoms include headaches, nausea, dizziness, difficulty concentrating, sugar cravings, muscle cramps and weakness, fatigue, gastrointestinal symptoms, and changes in heartbeat, which are commonly called the 'keto flu.' 

Despite the unpleasant symptoms at the beginning, a study showed a link between the ketogenic diet and self-reported emotional well-being, calmness, alertness, and emotional and cognitive stress. However, the self-reported nature of the results can affect their accuracy.⁵ Some studies suggest that the ketogenic diet can also be used as an adjunct therapy for people with mental conditions, but consulting a healthcare professional is crucial.⁶

Myth 4: Once You Lose Weight With Keto, You're Done For Good

Some people may think that if they follow the keto diet, they can lose a lot of weight quickly and then go back to their normal diet. But this doesn’t seem to be the case. 

A study compared weight loss and maintenance between a ketogenic diet and a personalized low-glycemic index diet. Low-glycemic index foods gradually raise blood sugar levels. They help prevent spikes. This makes them good for managing blood glucose and aiding weight loss.⁷

The study lasted 6 months, and then researchers followed up with participants at 18 months. In the first 6 months, those on the ketogenic diet lost 2.7 kg more than the other group. However, at 18 months, the keto group had regained 6.8 kg on average. Meanwhile, the low-GI group continued to lose weight, dropping another 4 kg. This was due to the keto group not adhering to the diet consistently in the long term. They reported not following the diet due to a lack of motivation, social events, holidays, and so on. Therefore, the sustainability of the diet is also important, as well as its effectiveness.⁷

Myth 5: People with Diabetes Can’t Follow a Ketogenic Diet

Some people think that those with diabetes can't follow the ketogenic diet because they believe ketosis and ketoacidosis are the same. Ketosis and ketoacidosis are two different things. Ketoacidosis is a serious condition where blood and urine ketone levels become dangerously high. It can occur in people with diabetes when blood glucose levels get too high or are poorly regulated, and this is known as diabetic ketoacidosis. It is a life-threatening condition.⁸

People with diabetes can be more prone to ketosis, and if ketone levels get too high, it can cause diabetic ketoacidosis.⁹ Therefore, much more caution is needed when following a ketogenic diet as a person with type 2 diabetes.¹º 

Some health authorities, such as Diabetes UK, do not recommend the ketogenic diet to people with diabetes due to the higher risk of ketoacidosis, as well as concerns about its efficacy and safety. However, it’s possible to do it under the supervision of a healthcare provider.¹¹ A recent meta-analysis has shown that a short-term ketogenic diet can improve fasting blood glucose, insulin sensitivity, and HbA1c levels in people with type 2 diabetes.¹² 

Myth 6: There Are No Limits On Fats

The ketogenic diet consists of 80-90% fat. Some of it comes from fats within foods such as eggs, meat, heavy cream, avocado, nuts, seeds, and other pure fats like beef tallow and olive oil. 

However, not all fats are equal. Some are high in saturated fats (mostly foods from animal origin), while others are high in unsaturated fats (mostly from plant origin). According to the American Heart Association, a heart-healthy diet consists mostly of unsaturated fats and a limited amount of saturated fats, not more than 6%, as well as avoiding trans fats.¹³

Mostly, people follow a ketogenic diet rich in saturated fats because animal products (which contain saturated fat) are likely to have little or no carbohydrates compared to plant-based fat sources. Some plant-based oils, such as coconut oil, are also high in saturated fats. 

However, high consumption of saturated fats is linked to death from heart disease.¹⁴ While a large study showed that a diet high in polyunsaturated fatty acids was linked to a 9% lower risk of dying from heart disease.¹⁵ So, researchers also asked what happens when a ketogenic diet is rich in unsaturated fats, mainly polyunsaturated fats. 

The study examined the effects of a ketogenic diet high in saturated fat (SAT group) vs. a ketogenic diet high in polyunsaturated fats (POLY group). The results showed that the POLY group significantly increased insulin sensitivity compared to the SAT group. While the SAT group had a significant increase in LDL (low-density lipoprotein, often referred to as "bad" cholesterol) and total cholesterol. However, the evidence is limited.¹⁶

Therefore, it seems that a ketogenic diet with limited saturated fat may be more beneficial than one high in saturated fat, although the evidence is still limited.

Myth 7: Ketogenic Diet Causes Cardiovascular Conditions 

The effects of a ketogenic diet on cardiovascular health are controversial. Some studies suggest benefits, while others say it can worsen important markers of heart health. A recent meta-analysis showed that ketogenic diets did increase total and LDL cholesterol. However, it also increased HDL (high-density lipoprotein, often referred to as "good" cholesterol"), reduced triglycerides, and lowered blood pressure, all of which are beneficial to heart health.¹⁷ 

However, some people may not be affected in the same way as others. In a study, twenty men with normal weight and no blood lipid conditions did not experience an increase in their LDL, but the diet was only followed for six weeks.¹⁸ Meanwhile, some individuals may experience excessive increases. A case study of a 56-year-old woman showed that her LDL exceeded the normal range after just four weeks of following the diet.¹⁹ Another 38-year-old man had an LDL level of 496 mg/dL, which is almost five times higher than the optimal level.²º A study also linked the ketogenic diet to a decreased risk of death from any cause without increasing the risk of death from cardiovascular diseases.²¹ 

Thus, duration and individual factors may be key components in this. It may be possible to follow a short-term keto diet and maintain cardiovascular health. However, it is best to consult your doctor, especially if you have a history of cardiovascular disease.

Myth 8: You Can Keep Following a Ketogenic Diet

Most people follow the keto diet for a short time. Although it is technically possible to continue following it, we don’t know enough about its safety and effectiveness in the long term.

One study followed children who stayed on the keto diet for over 6 years to manage epilepsy. After 6 years, some developed kidney stones, bone fractures, and high cholesterol.²² Another study examined people with type 1 diabetes on the keto diet for 10 years and found no harmful effects on their kidneys, thyroid, or bones. Therefore, the evidence remains unclear and limited.²³ 

In conclusion, the benefits you can get from a keto diet depend on many individual factors. Besides the benefits, there are risks as well, such as increasing the risk of nutrient deficiencies, high cholesterol levels, kidney stones, and fatty liver.²⁴ Therefore, it's crucial to consult your healthcare provider to get informed advice and guidance on the ketogenic diet for weight loss and supporting health.