Although the ketogenic diet may seem to be relatively new, it has been around for a long time. It was, in fact, a 100 years ago in 1921 that Dr Russel Wilder from the Mayo Clinic used a low carbohydrate, high fat diet, to reduce the severity and incidence of seizures in pediatric patients with epilepsy. He named the low carb, high fat diet that brought about changes similar to fasting as the 'ketogenic diet'. (1) The ketogenic diet, more commonly called the keto diet, became the main method of treating epilepsy in children for many years.
In recent years other health benefits of the keto diet have been reported and one of the most well-known health benefits of the keto diet has been its effectiveness as a weight loss tool. However, the health benefits of the keto diet extend beyond weight loss as the keto diet has the potential to support overall health and may help reduce the risk of some health conditions. But let's start with the basics.
A keto diet is a diet that restricts the amount of carbohydrates while increasing the fat content in the diet. By changing the amounts of these two nutrients, the keto diet basically changes how your body gets energy. The low carb intake on a keto diet forces the body to break down fats rather than carbohydrates as a source of energy.
In a typical diet, carbs provide 45 to 65% of the calories. The body uses the glucose released during carbohydrate metabolism as the main source of energy. Since you are consuming sufficient amount of calories from carbs, the fats from the diet are not needed for energy and are therefore stored as fat in the body. When carb intakes exceed needs, extra carbs are also converted and stored as body fat. This is the main cause of weight gain.
A keto diet, on the other hand, restricts the amount of carbs in the diet to provide only 5 to 10% of your calorie intake. (2) By limiting the amount of carbs, the body turns to other sources of energy and goes into a state of ketosis.
Ketosis is a natural response of the body that springs into action when carbohydrate intake is decreased or when food intake is low, like during fasting, and fat becomes the main source of energy. During ketosis, breakdown of fats in the liver produces ketones, which are used as fuel by most of the body, including the brain.
It takes some time for your body to enter ketosis, because ketosis can only start after all carbohydrate reserves in the body have been depleted. Depending on how strictly you follow the keto diet, your body may enter ketosis anywhere from a couple of days to three weeks after you start the keto diet. Learn more about signs your body is entering ketosis here.
Although the keto diet is very different from the typical diet eaten by most people and may be challenging for some, following the ketogenic diet provides many health benefits that range from losing weight and lowering blood sugar levels to improving memory. Read on to learn more about the health benefits of the keto diet.
Although not a typical weight loss diet, the keto diet has become popular as a diet that helps promote weight loss and may work for a number of reasons.
Unlike other popular diets that recommend a low fat diet, the keto diet is based on a high fat intake. A higher fat content in the diet has been found to reduce appetite and increase satiety by lowering hunger stimulating hormones. (3,4,5)
The suppressed appetite and increased feeling of fullness experienced on the keto diet is because it takes a longer time to digest fatty foods. Not feeling hungry when following a ketogenic diet leads to a lowered food intake and an overall reduction in total calorie intake, which makes the ketogenic diet a good diet for weight loss. (6) This has been supported by several studies.
A ketogenic diet review of 13 studies found that subjects on very-low-carb ketogenic diets lost more weight than those on a low fat diet. (7) Another meta-analysis review of 11 studies reported that subjects following a ketogenic diet that was a high fat, low carb diet for 6 months lost more weight than those on low fat diets. (8) A 2019 study also reported that participants on a very-low-carb ketogenic diet for 12 weeks lost more weight and had a greater reduction in their BMI (body mass index) than those on a low carbohydrate diet or moderate-low carbohydrate diet. (9)
A keto diet that limits the intake of carbs has the potential to help lower blood sugar and insulin levels in people with type 2 diabetes. (10) Patients with type 2 diabetes who followed a low carbohydrate ketogenic diet for six weeks lowered their hemoglobin A1C levels, blood sugar and improved glycemic control such that their diabetic medications were reduced or discontinued. (11) Similar results were found in another study that reported that type 2 diabetes patients had greater weight loss and waist circumference reduction as well as a decline in hemoglobin A1C levels and better blood sugar control in the group on the very low calorie ketogenic diet with low carbohydrate intake as compared to the control group on a standard low calorie diet. (12)
A meta-analysis of 13 studies that included a total of 567 subjects found that the ketogenic diet was effective in controlling fasting blood sugar levels, reducing hemoglobin A1C levels in addition to lowering blood pressure, BMI and body weight. The subjects also showed an improvement in their lipid metabolism – reported as lower levels of triglycerides, total cholesterol, and low-density lipoprotein (LDL cholesterol) while increasing high-density lipoprotein levels (HDL). (13)
Some scientific studies suggest that ketogenic diets may have powerful benefits for the brain and may help manage some symptoms of Alzheimer's disease and Parkinson's disease. (14, 15) The high fat, low carb keto diet brings the body to a state of ketosis, that leads to the production of ketone bodies which appear to have some neuroprotective effect on the aging brain cells.
Though more research is needed, ketones produced as a source of energy when on a ketogenic diet may decrease formation of amyloid plaques that accumulate in the brains of those with Alzheimer's disease and reverse their neurotoxicity.(16)
Two recent studies, published in 2019 and 2021, reported that a daily intake of a ketogenic medium chain triglyceride (MCT) drink for 6 months improved cognition - specifically memory, function and language, in those with mild cognitive impairment. (17,18)
Although the ketogenic diet was successful in treating patients with epilepsy, a chronic brain disorder that causes uncontrolled seizures, its use was discontinued when pharmaceutical drugs became available. (1) However, recent interest in the ketogenic diet has renewed the efforts of researchers to study the role it could play in reducing seizures and understand the possible benefits of the ketogenic diet in treating epilepsy.
A clinical trial conducted in 2008 on 145 children who did not respond to epileptic drugs found that children on the ketogenic diet had a 75% reduction in seizure frequency compared to those on the control diet. (19) Reviews of several studies have found the keto diet to be effective in children with drug-resistant epilepsy (20, 21) The Epilepsy Foundation recommends that children who do not respond to different medications for controlling their seizures may be prescribed the ketogenic diet by their physician. (22)
Women with polycystic ovary syndrome or PCOS experience several metabolic and endocrinal symptoms some of which include obesity, insulin resistance, type 2 diabetes, irregular menses and infertility. Though there is little research conducted on the effect of the ketogenic diet on PCOS, the rationale that they may be effective in reducing insulin resistance in overweight women with PCOS has been investigated in a few studies.
A pilot study conducted in 2005 on five women with PCOS who followed the ketogenic diet for six months reported that the women lost weight, had reduced fasting insulin levels and had improved ratios of the luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Two of the women suffering from infertility became pregnant during the study. (23)
A recent study published in 2020 also reported that 14 overweight women with polycystic ovarian syndrome who followed a Mediterranean version of the ketogenic diet for 12 weeks significantly lowered their body weight, body mass index, fat body mass and visceral adipose tissue. (24) A review article published in 2020 also found that the ketogenic diet may improve symptoms of PCOS. (25) While more research is needed, there is preliminary evidence that a ketogenic diet may be beneficial for some women with polycystic ovary syndrome.
Research on the benefits of the ketogenic diet has expanded to include its possible role in preventing and treating cancer. Some studies suggest that ketogenic diet may have an anti-tumor effect on certain cancers when used along with chemotherapy. (26) A 2020 review article concluded that the keto diet may change the metabolic environment and make it hard for cancer cells to grow.(27)
A 2021 study on women with early-stage breast cancer on radiotherapy reported that those following a ketogenic diet had an improved quality of life and metabolic health than those on a standard diet. (28) Results of another 2021 study that compared outcomes of breast cancer patients on a standard, low carb diet and a ketogenic diet during therapy found that both the ketogenic diet and low carb diets were beneficial in improving quality of life.(29)
Nonalcoholic fatty liver disease is a common chronic liver disease in Western countries that is linked to incidence of obesity. Left untreated, nonalcoholic fatty liver disease or NAFLD may lead to liver cirrhosis. (30) Weight loss through the use of ketogenic diet may provide a relatively easy treatment option for people suffering from nonalcoholic fatty liver disease, according to some studies.
A pilot study conducted in 2007 on five obese patients with NAFLD who followed a ketogenic diet with less than 20 grams of carbohydrates for 6 months reported improvement of the fatty liver disease as well as a significant weight loss.(30)
Results from another study also found that obese subjects with metabolic syndrome and NAFLD lost weight and lowered their low-density lipoprotein cholesterol (LDL), fasting plasma glucose, blood pressure and liver enzymes after 12 weeks on the ketogenic diet. (31)
Three recent articles published in 2020 review literature on use of ketogenic diets in obese patients with NAFLD report weight loss and decreased liver fat in short term studies. Authors of the articles recommend larger, long-term studies to assess the safety and efficacy of ketogenic diets on NAFLD. (32, 33, 34)
Children diagnosed with autism spectrum disorder (ASD) face several challenges some of which include anxiety, focus and attention problems, abnormal social interaction, difficulty with communication and in some cases, repetitive behaviors and interests. In addition, children with autism may suffer from seizures, a symptom observed in patients with epilepsy. (35,36)
Treatments for ASD include intensive behavioral therapy and medications, some of which may cause adverse effects, while changes in their diets may be an easier option. Using the rationale that the keto diet is effective in reducing frequency of seizures in epileptic subjects, researchers
studied the effect of ketogenic diet on symptoms of ASD. A review article cites several studies that showed that the ketogenic diet may be especially helpful for ASD patients with epilepsy.(35) A 2018 study found that children on a modified ketogenic diet supplemented with middle chain triglycerides (MCT) for three months displayed an improvement in some ASD behaviors. (36)
Migraine headaches that affect about 12% of the American population, according to the Migraine Research Foundation, can cause severe pain and may often be accompanied by sensitivity to touch, light and smell, nausea, vomiting and dizziness. (37)
The effect of the ketogenic diet may extend to decreasing symptoms of migraine headaches, according to some studies. Though long-term studies are needed, several short-term studies found that subjects on the keto diet reported fewer monthly attacks of migraine headaches and reduced their medication intake as compared to those on the standard diet. (38,39, 40, 41)
It is important for the brain to receive a steady supply of energy to function normally. Glucose, the main form of energy used by the brain, needs a special protein called glucose transporter type 1 (GLUT1) to carry glucose across the blood brain barrier into the brain. However, patients suffering from a rare genetic disorder called the glucose transporter type 1 deficiency syndrome or GLUT1DS have impaired glucose transporters (GLUT1), which decreases the amount of glucose entering the brain. The lack of energy available to the brain due to GLUT1DS causes seizures, cognitive impairment, epilepsy and movement disorders. (42)
The ketogenic diet has become a gold standard for life-long treatment of patients with GLUT1DS because it provides ketone bodies as a source of energy for the brain. Ketones do not need glucose transporters to reach the brain.
Studies show that the ketogenic diet improved the quality of life, alertness and reduced frequency of seizures. (42, 43) Though more research is needed, the keto diet appears to be effective in reducing symptoms of GLUT1DS and may be an alternate treatment option available for those suffering from GLUT1DS.
Now that you know about some of the benefits of the keto diet, you may want to learn more about the diet itself. What you probably know by now is that the ketogenic diet is a very restrictive diet and is not like the typical low fat diets that help you lose weight. In fact, the keto diet will definitely need you to change your eating habits as it particularly limits the amount of carbohydrates you can eat and is one of the main reason it is hard to follow for a long time.
Also, unlike a low fat diet, the keto diet will require you to eat high fat foods. A side effect of eating fatty foods, especially those rich in saturated fats, is putting your heart health at risk of heart disease. To reduce risk of heart disease and maintain heart health, it important that you chose foods that contain healthy fats.
Before starting on the keto diet, it is important to learn as much as you can about the staple foods you can eat from the different food groups while on the keto diet and, also, what foods to avoid. You can learn more about the benefits and possible side effects of the keto diet.
While benefits of keto diet in helping lose weight and other health conditions are promising, it is important you consult your doctor before starting on the keto diet – especially if have any existing health conditions.
The keto diet works because it forces your body to enter nutritional ketosis that helps with fat loss that leads to weight loss. To understand how the keto diet works, it is important to know what is ketosis and how you can tell if you are entering ketosis.