Ketogenic diets have become incredibly popular.
Early research suggests this high-fat, very low-carb diet may benefit several health conditions.
Although some of the evidence is from case studies and animal research, results from human controlled studies are also promising.
Here are 15 health conditions that may benefit from a ketogenic diet.
Epilepsy is a disease that causes seizures due to excessive brain activity.
Anti-seizure medications are effective for some people with epilepsy. However, others don't respond to the drugs or can't tolerate their side effects.
Of all the conditions that may benefit from a ketogenic diet, epilepsy has by far the most evidence supporting it. In fact, there are several dozen studies on the topic.
Research shows that seizures typically improve in about 50% of epilepsy patients who follow the classic ketogenic diet. This is also known as a 4:1 ketogenic diet because it provides 4 times as much fat as protein and carbs combined (1, 2, 3).
The modified Atkins diet (MAD) is based on a considerably less restrictive 1:1 ratio of fat to protein and carbs. It has been shown to be equally effective for seizure control in most adults and children older than two years of age (4, 5, 6, 7, 8).
The ketogenic diet may also have benefits on the brain beyond seizure control.
For example, when researchers examined the brain activity of children with epilepsy, they found improvements in various brain patterns in 65% of those following a ketogenic diet — regardless of whether they had fewer seizures (9).
Bottom Line: Ketogenic diets have been shown to reduce seizure frequency and severity in many children and adults with epilepsy who don't respond well to drug therapy.
Metabolic syndrome, sometimes referred to as prediabetes, is characterized by insulin resistance.
You can be diagnosed with metabolic syndrome if you meet any 3 of these criteria:
- Large waistline: 35 inches (89 cm) or higher in women and 40 inches (102 cm) or higher in men.
- Elevated triglycerides: 150 mg/dl (1.7 mmol/L) or higher.
- Low HDL cholesterol: Less than 40 mg/dL (1.04 mmol/L) in men and less than 50 mg/dL (1.3 mmol/L) in women.
- High blood pressure: 130/85 mm Hg or higher.
- Elevated fasting blood sugar: 100 mg/dL (5.6 mmol/L) or higher.
People with metabolic syndrome are at increased risk of diabetes, heart disease and other serious disorders related to insulin resistance.
Fortunately, following a ketogenic diet may improve many features of metabolic syndrome. Improvements may include better cholesterol values, as well as reduced blood sugar and blood pressure (10, 11, 12, 13, 14).
In a controlled 12-week study, people with metabolic syndrome on a calorie-restricted ketogenic diet lost 14% of their body fat. They decreased triglycerides by more than 50% and experienced several other improvements in health markers (14).
Bottom Line: Ketogenic diets may reduce abdominal obesity, triglycerides, blood pressure and blood sugar in people with metabolic syndrome.
People with glycogen storage disease (GSD) lack one of the enzymes involved in storing glucose (blood sugar) as glycogen or breaking glycogen down into glucose. There are several types of GSD, each based on the enzyme that is missing.
Typically, this disease is diagnosed in childhood. Symptoms vary depending on the type of GSD, and may include poor growth, fatigue, low blood sugar, muscle cramps and an enlarged liver.
However, early research suggests that a ketogenic diet may benefit people with some forms of GSD.
For example, GSD III, also known as Forbes-Cori disease, affects the liver and muscles. Ketogenic diets may help relieve symptoms by providing ketones that can be used as an alternate fuel source (15, 17, 18).
GSD V, also known as McArdle disease, affects the muscles and is characterized by a limited ability to exercise (19).
In one case, a man with GSD V followed a ketogenic diet for one year. Depending on the level of exertion required, he experienced a dramatic 3- to 10-fold increase in exercise tolerance (20).
However, controlled studies are needed to confirm the potential benefits of ketogenic diet therapy in people with glycogen storage disease.
Bottom Line: People with certain types of glycogen storage disease may experience a dramatic improvement in symptoms while following a ketogenic diet. However, more research is needed.
Polycystic ovary syndrome (PCOS) is a disease marked by hormonal dysfunction that often results in irregular periods and infertility.
One of its hallmarks is insulin resistance, and many women with PCOS are obese and have a hard time losing weight. Women with PCOS are also at an increased risk for type 2 diabetes (21).
Those who meet the criteria for metabolic syndrome tend to have symptoms that affect their appearance. Effects may include increased facial hair, acne and other signs of masculinity related to higher testosterone levels (22).
In a 6-month study of eleven women with PCOS following a ketogenic diet, weight loss averaged 12%. Fasting insulin also declined by 54% and reproductive hormone levels improved. Two women suffering from infertility became pregnant (24).
Bottom Line: Women with PCOS following a ketogenic diet may experience weight loss, reduction in insulin levels and improvement in reproductive hormone function.
People with diabetes often experience impressive reductions in blood sugar levels on a ketogenic diet. This is true of both type 1 and type 2 diabetes.
In a 16-week study, 17 of 21 people on a ketogenic diet were able to discontinue or decrease diabetes medication dosage. Study participants also lost an average of 19 pounds (8.7 kg) and reduced their waist size, triglycerides and blood pressure (28).
In a 3-month study comparing a ketogenic diet to a moderate-carb diet, people in the ketogenic group averaged a 0.6% decrease in HbA1c. 12% of participants achieved an HbA1c below 5.7%, which is considered normal (29).
Bottom Line: Ketogenic diets have been shown to reduce blood sugar in people with diabetes. In some cases, values return to a normal range, and medications can be discontinued or reduced.
Cancer is one of the leading causes of death worldwide.
Many researchers note that elevated blood sugar, obesity and type 2 diabetes are linked to breast and other cancers. They suggest that restricting carbs in order to lower blood sugar and insulin levels may help prevent tumor growth (31, 32).
Case studies and patient data analyses have found improvements in various types of brain cancer, including glioblastoma multiforme (GBM) — the most common and aggressive form of brain cancer (39, 40, 41).
One study found 6 out of 7 GBM patients had a modest response to an unrestricted-calorie ketogenic diet combined with an anti-cancer drug. Researchers noted that the diet is safe but probably of limited use alone (42).
Although it may not have a significant impact on disease progression in advanced and terminal cancers, the ketogenic diet has been shown to be safe in these patients and potentially improve quality of life (45, 46, 47).
Randomized clinical studies need to examine how ketogenic diets affect cancer patients. Several are currently underway or in the recruiting process.
Bottom Line: Animal and human research suggests ketogenic diets may benefit people with certain cancers, when combined with other therapies.
Autism spectrum disorder (ASD) refers to a condition characterized by problems with communication, social interaction and, in some cases, repetitive behaviors. Usually diagnosed in childhood, it is treated with speech therapy and other therapies.
Autism shares some features with epilepsy, and many people with autism experience seizures related to the over-excitement of brain cells.
A pilot study of 30 children with autism found that 18 showed some improvement in symptoms after following a cyclical ketogenic diet for 6 months (53).
In one case study, a young girl with autism who followed a gluten-free, dairy-free ketogenic diet for several years experienced dramatic improvements. These included resolution of morbid obesity and a 70-point increase in IQ (54).
Randomized controlled studies exploring the effects of a ketogenic diet in ASD patients are now underway or in the recruiting process.
Bottom Line: Early research suggests some people with autism spectrum disorders may experience improvements in behavior when ketogenic diets are used in combination with other therapies.
Parkinson's Disease (PD) is a nervous system disorder characterized by low levels of the signaling molecule dopamine.
The lack of dopamine causes several symptoms, including tremor, impaired posture, stiffness and difficulty walking and writing.
In an uncontrolled study, seven people with PD followed a classic 4:1 ketogenic diet. After 4 weeks, five of them averaged a 43% improvement in symptoms (60).
The effects of a ketogenic diet on PD is another area that needs controlled studies.
Bottom Line: The ketogenic diet has shown promise in improving symptoms of Parkinson's disease in both animal and human studies. However, high-quality research is needed.
What's more, they typically provide other health improvements as well.
In a 24-week study, men who followed a ketogenic diet lost twice as much fat as men who ate a low-fat diet (65).
In addition, the ketogenic group's triglycerides dropped significantly, and their HDL ("good") cholesterol increased. The low-fat group had a smaller drop in triglycerides and a decrease in HDL cholesterol.
Ketogenic diets' ability to reduce hunger is one of the reasons why they work so well for weight loss.
A large analysis found that very low-carb, calorie-restricted ketogenic diets help people feel less hungry than standard calorie-restricted diets (66).
Even when people on a ketogenic diet are allowed to eat all they want, they generally end up eating fewer calories due to the appetite-suppressing effects of ketosis.
In a study of obese men who consumed either a calorie-unrestricted ketogenic or moderate-carb diet, those in the ketogenic group had significantly less hunger, took in fewer calories and lost 31% more weight than the moderate-carb group (67).
Bottom Line: Studies have found that ketogenic diets are very effective for weight loss in obese people. This is largely due to their powerful appetite-suppressing effects.
Glucose transporter 1 (GLUT1) deficiency syndrome, a rare genetic disorder, involves deficiency of a special protein that helps move blood sugar into the brain.
Symptoms usually begin shortly after birth and include developmental delay, difficulty with movement and sometimes seizures.
Unlike glucose, ketones don't require this protein to cross from the blood to the brain. Therefore, the ketogenic diet can provide an alternative fuel source that these children's brains can use effectively.
Indeed, ketogenic diet therapy seems to improve several symptoms of the disorder. Researchers report decreased seizure frequency and improvement in muscle coordination, alertness and concentration in children on ketogenic diets (68, 69, 70).
As with epilepsy, the modified Atkins diet (MAD) has been shown to provide the same benefits as the classic ketogenic diet. However, the MAD offers greater flexibility, which may result in better compliance and fewer side effects (71, 72, 73).
In a study of 10 children with GLUT1 deficiency syndrome, those who followed the MAD experienced improvements in seizures. At six months, 3 out of 6 became seizure-free (73).
Bottom Line: Both the classic ketogenic diet and more flexible MAD have been shown to improve seizures and other symptoms in children with GLUT1 deficiency syndrome.
Traumatic brain injury (TBI) most commonly results from a blow to the head, a car accident or a fall in which the head strikes the ground.
It can have devastating effects on physical function, memory and personality. Unlike cells in most other organs, injured brain cells often recover very little, if at all.
Rat studies suggest that starting a ketogenic diet immediately after brain injury can help reduce brain swelling, increase motor function and improve recovery. However, these effects appear to occur mainly in younger rather than older rats (76, 77, 78).
That said, controlled studies in humans are needed before any conclusions can be reached.
Bottom Line: Animal studies show that a ketogenic diet improves outcomes in rats fed a ketogenic diet after traumatic brain injury. However, there are currently no quality human studies on this.
Multiple sclerosis (MS) damages the protective covering of nerves, which leads to communication problems between the brain and body. Symptoms include numbness and problems with balance, movement, vision and memory.
As with other nervous system disorders, MS appears to reduce the cells' ability to use sugar as a fuel source. A 2015 review discussed ketogenic diets' potential to assist with energy production and cell repair in MS patients (80).
Additionally, a recent controlled study of 48 people with MS found significant improvements in quality of life scores, cholesterol and triglycerides in the groups who followed a ketogenic diet or fasted for several days (81).
More studies are currently underway.
Bottom Line: Studies about the potential benefits of a ketogenic diet for treating MS are promising. However, more human studies are needed.
Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in the Western world.
In a small study, 14 obese men with metabolic syndrome and NAFLD who followed a ketogenic diet for 12 weeks had significant decreases in weight, blood pressure and liver enzymes (84).
What's more, an impressive 93% of the men had a reduction in liver fat, and 21% achieved complete resolution of NAFLD.
Bottom Line: Ketogenic diets may be very effective at reducing liver fat and other health markers in people with nonalcoholic fatty liver disease.
Alzheimer's disease is a progressive form of dementia characterized by plaques and tangles in the brain that impair memory.
Interestingly, Alzheimer's disease appears to share features of both epilepsy and type 2 diabetes: seizures, the inability of the brain to properly use glucose and inflammation linked to insulin resistance (85, 86, 87).
Animal studies show that a ketogenic diet improves balance and coordination but doesn't affect the amyloid plaque that is a hallmark of the disease. However, supplementing with ketone esters appears to reduce amyloid plaque (88, 89, 90).
For example, one controlled study followed 152 people with Alzheimer's disease who took an MCT compound. After 45 and 90 days, this group showed improvements in mental function, while the placebo group's function declined (93).
Controlled studies testing the modified Atkins diet and MCT oil in people with Alzheimer's disease are currently in progress or in the recruiting stage.
Bottom Line: Several symptoms of Alzheimer's disease have been shown to improve with ketogenic diets in animal research. Human studies suggest supplementing with MCT oil or ketone esters may be beneficial.
Migraine headaches typically involve severe pain, sensitivity to light and nausea.
One observational study reported a reduction in migraine frequency and pain medication use in people following a ketogenic diet for one month (96).
An interesting case study of two sisters following a cyclical ketogenic diet for weight loss reported that their migraine headaches disappeared during the 4-week ketogenic cycles but returned during the 8-week transition diet cycles (97).
However, high-quality studies are needed to confirm the results of these reports.
Bottom Line: Some studies suggest that migraine headache frequency and severity may improve in people following a ketogenic diet.
Ketogenic diets are being considered for use in several disorders due to their beneficial effects on metabolic health and the nervous system.
However, many of these impressive results come from case studies and need validation through higher-quality research, including randomized controlled trials.
With respect to cancer and several other serious diseases on this list, a ketogenic diet should be undertaken only in addition to standard therapies under the supervision of a doctor or qualified healthcare provider.
Also, no one should consider the ketogenic diet a cure for any disease or disorder on its own.
Nonetheless, the ketogenic diets' potential to improve health is very promising.
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