The term “keto diet” is one of the most popular food and health-related search terms on the internet. Unlike fad diets, like the master cleanse and the grapefruit diet, which lose popularity almost as quickly as they gain it, the ketogenic diet as a way to lose weight swiftly has maintained widespread popularity for over a decade.
But, beyond weight loss, is the keto diet effective for helping to manage chronic diseases?
As a health and nutrition coach, you have probably looked into, or even tried, the ketogenic diet. It is also likely that several of your clients have asked you about it.
However, it can be difficult to discern between research-backed facts and information potentially skewed by companies that profit from ketogenic products and services. To clear up the fog, here we look into the research behind the effectiveness of the ketogenic diet, not as a weight loss diet, but as an eating pattern that may benefit people with serious health conditions.
Keto Diet 101
What Exactly Is the Ketogenic Diet?
From a nutritional perspective, the keto diet is an eating regimen that is very high in fats, moderate in protein, and very low in carbohydrates. The guiding principle is that, by consuming most of your calories from fats rather than from carbohydrates, your body switches from steadily depending on carbohydrates for energy to depending on fat for energy.
Unless a person is on a low-calorie ketogenic diet, calorie consumption isn’t usually restricted; instead, it focuses on macronutrient distribution. While there isn’t a standard agreement on calorie distribution between macronutrients, most sources talk about people on a ketogenic diet getting about 70% of their daily calories from fat, about 25% calories from protein, and a maximum of 5% of calories (or 20 to 50g) from carbohydrates.
Why Was the Keto Diet Invented?
Many people in the health and wellness field categorize the keto diet as a “fad diet.” However, the use of the keto diet for weight loss and muscle gain in the short term is a recent application.
The ketogenic diet was originally created as a therapeutic diet to successfully treat epilepsy almost one hundred years ago.
Dr. Wilder was the first to formulate the hypothesis that the ketogenic diet would be beneficial for reducing the number of epileptic attacks in people affected by epilepsy in the 1920s. After observing that fasting seemed to reduce the number of epileptic attacks, he tested the theory that a diet high in fat and very low in carbohydrates would also be beneficial. The multiple studies that Wilder and his team conducted all found that a ketogenic-style diet was beneficial for managing epilepsy.
Leading up to the 2000s, researchers experimented with the ketogenic diet for a number of other conditions, from type 2 diabetes to pediatric nutrition to Rett syndrome. More recently, it has been used to support athletic endurance and, popularly, to support weight loss.
You can read more about the history and evolution of the keto diet here.
The Science of Calories
All of the body’s cells need energy to carry out regular functions. Chemists, food scientists, and health professionals agreed to use the quantified form of this energy, which is kilocalories, or kCal, to help the general public gain a better understanding of the energy their bodies need and how different foods contribute to those energy needs.
The cells that make up heart muscles, called cardiac myocytes, need energy to move ions in and out of the cell that causes muscles to contract.
Brain cells, called neurons, need energy to move impulses between cells.
Besides these two examples, there are hundreds of other types of cells and an estimated 32.7 trillion total cells in the body (that is 32,700,000,000,000 cells!). Logically, these cells need plenty of energy that they get from the food we eat.
Cells are wired to use glucose as their ideal source of energy. This is because it is easily broken down in the digestive system, and it can be easily stored in the form of glycogen in the muscles and liver for backup energy. Glucose is a simple sugar that is most easily broken down from carbohydrates, but it can also be made from protein sources and from stored glycogen in the muscles and liver.
The Metabolism: Balancing Energy Needs
Contrary to popular belief, the metabolism isn’t something that must be “sped up” or “slowed down” after taking supplements or exercising. Metabolism is a term used to describe the chemical reactions that happen in our body to keep your cells doing their jobs—including breaking down macronutrients that provide energy to cells.
The best way of understanding the difference between what happens to our body when we get our energy from either fats or carbohydrates is by looking into how our body evolved to process each of those macronutrients. We summarize this evolutionary process below:
- From an evolutionary perspective, researchers have found that human cells likely developed to “prefer” glucose as their main source of energy because, for all of human history, carbohydrate-rich foods have been easily accessible year-round, whereas fat-rich and protein-rich foods tended to be much more scarce.
- Even today, carbohydrates also tend to be the macronutrient that is cheapest (in monetary and ecological terms) and most accessible of all the macronutrients.
- In times of abundance, our bodies fill up glycogen stores and begin to store additional energy as fat. In hunter-gatherer times, this was beneficial because their bodies pulled from fat stores when food supply was low, such as famine and seasonal hunger.
- One of the main theories behind the reason why digestible carbohydrates, and thus glucose, were so important in the human diet was that the body needed access to additional energy for the growing brain of the human species. At the same time, however, dietary fat was also needed to build the brain.
- When food was scarce, our body could still access energy stores in the fat for a short period of time. To take advantage of stored fat, the body breaks adipose tissue down into components called ketone bodies, or ketones for short. Most cells in our body are able to use ketones instead of glucose as energy. Ketone bodies are the basis of the ketogenic diet.
- The body can also use protein as energy, but its primary job in the body is to make hormones, muscles, and enzymes and transport proteins. In certain conditions, the body can break down protein from muscles and the diet to make glucose.
Unlike a diet rich in fruits, vegetables, herbs, and whole grains that our ancestors ate, Western-style diets tend to be rich in refined carbohydrates. These carbohydrates tend to be void of fiber, vitamins, and minerals.
While the consumption of complex carbohydrates is linked to a reduction in the risk of chronic disease, the consumption of refined carbohydrates is linked to a number of chronic diseases, including type 2 diabetes, heart disease, and cancer.
What Happens When We Eat Mostly Fat?
The ketogenic diet is based on a high, steady supply of fat, a moderate supply of protein, and a very low supply of carbohydrates.
When this happens, cells switch from using glucose as their main source of energy to using ketones, the product of fat breakdown. After several days of consuming a ketogenic diet, your body will achieve nutritional ketosis, which is a natural state that occurs when the metabolism is accommodated to the intentional increase in fat consumption.
On the keto diet, the body goes into a steady state of breaking down fat in the body or from the diet into ketones, and our cells use these as energy.
Most organs in the body can use ketones instead of glucose as energy. The muscles, the heart, and the brain, which have high energy demands, use ketones most readily.
However, the liver cells, also known as hepatic cells, cannot use ketone bodies as fuel, so they continue to need glucose to function. This means that even people on very-low-carbohydrate diets, like the ketogenic diet, need to continue to consume some glucose-containing carbohydrates to prevent muscle breakdown.
The Ketogenic Diet as Therapy: Can It Help Manage Chronic Health Conditions?
Recently, the ketogenic diet is being revisited as one that might truly have the potential to help manage, and even reverse, a number of chronic health conditions.
What are these conditions? Is the ketogenic diet effective in treating them?
Here, we look at the evidence around the use of the ketogenic diet for managing the symptoms or reversing the effects of five health conditions.
As a reminder, regardless of the evidence behind the effectiveness of the keto diet as part of a therapy plan, if you have a client or patient with a chronic health condition, it is important that you work with their entire health team to make sure that a keto diet works as part of their treatment plan before assisting them in adopting a ketogenic diet.
One hundred years after it was first used to treat epilepsy, ketogenic diet therapy (KDT) is now considered an evidence-based treatment for epilepsy and is safe and tolerable for children. Researchers now have a much better understanding of the role of ketosis in reducing the number and intensity of seizures.
How does it work? The abundance of ketone bodies and scarcity of glucose disrupt certain neural connections (called glutamatergic synaptic transmissions), inhibit the generation of more glucose, and activate potassium channels, which helps to control muscle spasms.
How effective is the ketogenic diet for controlling seizures? One meta-analysis looked at the effect of the ketogenic diet in children with epilepsy. The research showed that infants on the ketogenic diet for more than one month had a reduction in epileptic attacks by up to 50%, and 33% of infants no longer had any seizures after being on the ketogenic diet.
More research on the long-term effects of a ketogenic diet on children with epilepsy needs to be conducted.
Metabolic Syndrome and Type 2 Diabetes
The use of the ketogenic diet to manage glucose levels in people with metabolic diseases is intriguing to many who are at risk of metabolic diseases like pre-diabetes and type 2 diabetes.
The theoretical mechanism behind the ketogenic diet for managing diabetes is as follows: The keto diet significantly restricts carbohydrates, so the body switches from using glucose to using ketones. As a result, blood glucose levels, one of the main indicators of metabolic health, remain stable, and insulin requirements go down as well.
Studies that have examined the application of the ketogenic diet for glucose levels found that people with type 2 diabetes who were also overweight resulted in a reduction in body weight and an improvement in glycemic control.
A systematic review and meta-analysis confirmed that low-carbohydrate diets, including ketogenic diets, helped to control glucose in type 2 diabetes patients, and it had a positive effect on triglyceride and HDL cholesterol levels. They didn't, however, show a reduction in weight in the long term.
Other research groups, however, highlight the possible risks of a ketogenic diet for people with type 2 diabetes. Since the ketogenic diet changes how our bodies use insulin, it can lead to insulin resistance and raise the risk for type 2 diabetes in people who have healthy insulin production. In other words, this study suggests that following the diet when you don’t have diabetes could raise the risk of developing diabetes.
Additionally, some people with diabetes who are ketone-prone are more at risk of facing complications. Implementation of the keto diet without supervision is widespread, and there is a lack of guidelines for the use of the ketogenic diet as part of a treatment regimen for diabetes.
Initial evidence is promising, but the enthusiasm around the implementation of the ketogenic diet as part of standard practice for managing metabolic conditions, like type 2 diabetes, exceeds the evidence health professionals have available to have full confidence in recommending it. Researchers still do not know how a keto diet impacts diabetes in the long term.
If a person with a metabolic disease and the healthcare team agree that a ketogenic diet can be integrated with the overall treatment plan, it is important that everyone be aware of the risks of the diet, as well as the benefits.
The use of the ketogenic diet in people with cancer is a controversial topic. In theory, the nutritional ketosis caused by a ketogenic diet could cause oxidative stress in cancer cells but not in healthy cells. Experiments in animals have shown that the ketogenic diet is effective against the metastasis of cancer. Specific case studies for certain cancers have shown some evidence of cancer regression.
Some of the risks include uncomfortable, sometimes dangerous side effects that may compound in people undergoing cancer treatment, including nausea and weight loss.
Of course, there are hundreds of different types of cancer, and each type of cancer has a unique pathology and genesis. The current research only covers the tip of the iceberg in terms of the impact of the ketogenic diet on the development of different types of cancer, which is why the keto diet is not part of any cancer treatment guidelines.
The scientific and medical community needs consistent clinical evidence about the effectiveness of the ketogenic diet to either slow tumor growth, prevent cancer, or improve symptoms before recommending the keto diet for any cancer diagnosis.
Alzheimer’s Disease and Parkinson’s Disease
The success of ketogenic diets in the treatment of epilepsy, which originates in the brain, brought about the question of the effectiveness of the ketogenic diet for treating other diseases that originate in the brain.
The ketogenic diet is proposed to have protective effects on the brain of people with neurodegenerative diseases like Alzheimer’s disease and Parkinson’s disease. In fact, some hypotheses propose that the keto diet might even be able to modify the effects of the disease, including reducing symptoms.
Several small studies with human participants have shown a reduction in symptoms of neurodegenerative diseases.
Some of the theories of how the ketogenic diet might have a positive effect on the health of people with these diseases is that the high concentrations of ketones enhance neuronal energy reserves, which improve the ability of brain cells to resist and recover from metabolic issues that affect brain health. The antioxidant and anti-inflammatory effects specific to the ketogenic diet may also have a role.
However, the ketogenic diet may not be well-accepted by people with moderate to advanced neurodegenerative diseases or as a long-term treatment. At the same time, elderly people, who tend to be most at risk of having Alzheimer’s and Parkinson’s disease, are also at risk of having a reduced appetite and malnutrition. So, as researchers gain a better understanding of why the ketogenic diet might be effective, they will likely propose alternatives that still take advantage of the effects without the need for adopting a full-on ketogenic diet.
Thus, while some data shows that the ketogenic diet may be effective for people with very mild or mild Alzheimer’s disease or Parkinson’s disease, it may pose risks on the nutritional status of elderly people, who tend to be most affected by these conditions. Ultimately, there isn’t enough information on the long-term application of the ketogenic diet to apply it as part of a standard therapy for neurodegenerative diseases.
Nonalcoholic Fatty Liver Disease
Nonalcoholic Fatty Liver Disease (NAFLD) is a common disease where excess fat accumulates in the liver. Since fatty liver could result from drinking too much alcohol, this condition is different in that it arises in people who drink little to no alcohol.
The people who are at most risk of developing NAFLD have diabetes or insulin resistance; are overweight or obese; or have elevated cholesterol, triglycerides, or blood pressure.
A clinical study carried out with people with NAFLD who implemented the ketogenic diet with nutritional supplementation for six months not only saw improvements in liver health, but the people also experienced significant weight loss.
However, long-term implementation of the ketogenic diet in previously healthy mice actually stimulated the development of NAFLD.
The weight-loss effects in addition to the macronutrient distribution of the keto diet seem to slow the progression and reverse the effects of NAFLD. However, the medical community worries that healthy individuals may develop NAFLD when on the keto diet in the long term.
More research needs to be carried out to make conclusions about the short-term and long-term effects of the keto diet for NAFLD treatment.
What Works: Plant-Based Diets for Chronic Disease
While the keto diet is not proven to be effective for most therapeutic uses, it is not the only option.
There are dietary patterns that people can adopt that research consistently shows are effective in reducing risk. Plant-based diets are one of the primary lifestyle recommendations physician organizations are beginning to make for people who are at risk of or managing chronic disease.
Not only are plant-based diets relatively easily achieved, research shows, time and time again, that the adoption of plant-based diets on individual and societal levels can significantly reduce the burden of chronic disease and help people effectively manage diseases.
Of the five chronic health conditions reviewed here, the ketogenic diet is only standard treatment in individuals who have epilepsy.
For all other conditions, the medical community requires larger, longer-period studies in both healthy and ill individuals that demonstrate consistent, positive effects in certain populations prior to making overall recommendations to follow a keto diet. Until then, health professionals should not make generalizations about the use of the keto diet for the treatment of serious health conditions.
Plant-based diets continue to lead the way in research-backed lifestyle changes that people can make to reduce their risk of disease and manage disease.