Ketogenic Diet (Keto Diet)

Medically Reviewed on 1/9/2024

What is the ketogenic diet?

 Ketogenic is a term for a low-carb diet
Ketogenic is a term for a low-carb diet.

The ketogenic diet is a diet that produces reactions in the body similar to those that occur during fasting. This is a type of extreme low-carb diet that was first developed in 1921 due to the ability of this type of diet to reduce or suppress seizures. As new medications to treat seizures were developed, the ketogenic diet became less popular as a way to manage seizure disorders. However, in 2008, a clinical trial showed that a ketogenic diet could help children with treatment-resistant epilepsy become seizure-free. A ketogenic diet is often prescribed for people who have failed two mainline anti-seizure drugs, with studies showing seizure-reduction rates as high as 85% after this treatment. It can be effective for patients of any age or seizure type. The reasons why a ketogenic diet works to help reduce seizures are unclear, but it is believed to induce metabolic changes that lower the risk of seizures.

The diet itself is a low-carb, high-fat diet that involves extreme reduction of carbohydrate consumption and replacing it with fat, up to a concentration of 70%-80% of calories from fat. There is no one standard ketogenic diet, and different ratios of nutrients have been used in so-called keto diets. All have in common the reduction of carbohydrates and an increase in fat along with a moderate amount of protein.

The reduction in carbohydrates deprives the body of glucose and causes a metabolic state known as ketosis, due to the accumulation of molecules known as ketones in the bloodstream. Ketones consist of acetoacetate, acetone, and beta-hydroxybutyrate and form in the liver from long- and medium-chain fatty acids when the body burns stored fat for energy after glucose is depleted or in situations in which there is inadequate insulin present for glucose to be used as energy. In addition to seizure disorders, ketogenic diets have been tested in the management of some people with other conditions including diabetes, cancer, polycystic ovary syndrome, and Alzheimer's disease.

Further, the "keto diet" has gained attention as a potential weight-loss tool. Its proponents argue that a carefully controlled ketogenic diet can avoid the dangers of ketoacidosis and be an effective way to lose weight.

What is ketosis?

Ketosis is the accumulation of ketone bodies or ketones in the blood. Ketosis occurs in healthy people during fasting and strenuous exercise. In excess, blood ketones can produce a toxic level of acid in the blood, referred to as ketoacidosis.

  • Ketoacidosis is a known and life-threatening complication of type 1 diabetes and has been described in some cases as healthy people eating a very low-carbohydrate diet.

What are different types of the ketogenic diet?

Since ketosis can be achieved in various ways, there are several types of the ketogenic diet:

  1. Standard ketogenic diet: This is the most popular version of the ketogenic diet and one with the most research. A standard ketogenic diet incorporates very low carbs (about 5%-10% of total calorie intake), moderate protein (about 20% of total calorie intake), and high fats (about 70%-75% of total calorie intake). This is the most recommended version for people seeking weight loss and blood sugar control.
  2. Targeted ketogenic diet: This type of ketogenic diet is mainly recommended for athletes to enhance their performance. In a targeted ketogenic diet, additional carbs are allowed around periods of extensive physical activity such as 30-45 minutes before an athletic event. Carbs should be easy to digest so that once the athletic event is finished, ketosis can be achieved with the conventional ketogenic dietary pattern.
  3. Cyclical ketogenic diet: Adhering to a ketogenic diet can be difficult. The cyclical pattern of a ketogenic diet makes it easier to follow. As the name suggests, a cyclical ketogenic diet, also called keto-cycling, involves ketogenic diet cycles interspersed with periods of higher carb intake. For example, the person may follow a ketogenic diet for five days of the week, and for the next two days, they can consume a higher amount of carbs. This version is best suited for people who find it too difficult to stick to the ketogenic diet.
  4. High-protein ketogenic diet: This version of a ketogenic diet is mainly suited to people with high protein requirements such as bodybuilders. It incorporates about 30%-35% protein, 60%-65% fats and 5% carbs.

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How does your body lose weight in ketosis?

Ketosis occurs when your body does not have enough sugars to burn for energy, so it burns fats instead, leading to weight loss. This is the principle behind the keto diet.

Normally, your body uses carbohydrates from the food you eat or from glycogen (carbs stored in the liver) as a preferred source of energy. When you eat fewer carbs, your body cannot make glycogen and thus turns to fats to use for energy. Your liver breaks down fats into substances called ketones, which are byproducts of fat metabolism. Glucose is the main source of energy for your brain. Therefore, when you follow a low-carb diet, a larger portion of your brain will use ketones for energy as well.

The high-fat content of the keto diet makes you feel full throughout the day, helping you cut down on your overall eating. In the long term, a ketogenic diet suppresses your appetite, which causes you to consume fewer calories.

How to achieve ketosis

Fasting is the quickest way to achieve ketosis. However, this will work only for a few days and is not ideal because you are not getting enough important nutrients. The best way to achieve ketosis is to go on a low-carb diet or follow a ketogenic (keto) diet, which is a low-carb high-fat diet that restricts your carb intake to fewer than 50 grams per day to as little as 20 grams per day. The level of carbohydrates to induce ketosis varies from person to person.

How long does it take to lose weight in ketosis?

Ketosis is a metabolic state in which the body uses fat as fuel instead of carbs. According to proponents of the keto diet, ketosis is key to quick weight loss. It can take 2-4 days or longer to start losing weight in ketosis, although the rate of weight loss depends on various factors such as your metabolism, carb-protein-fat intake, fitness level, and how strictly you follow the diet.

How many carbs will disrupt ketosis?

Most ketogenic diet guidelines recommend limiting your total carbohydrate intake to 15-30 grams or 5%-10% of your total calorie intake a day. Eating more than 50 grams of carbs may disrupt ketosis.

Top 11 signs you are in ketosis

The following 11 signs and symptoms indicate the body is in ketosis:

  1. Feeling tired or fatigued (typically short-term)
  2. Bad breath
  3. Dry mouth
  4. Increased thirst
  5. Decreased urination
  6. Change in bowel movements (diarrhea or constipation)
  7. Decreased appetite
  8. Decreased hunger
  9. Weight loss
  10. Experiencing flu symptoms, such as headache and nausea
  11. Insomnia

Can you tell by your urine if you are in ketosis?

You can tell by your urine that you are in ketosis using over-the-counter urine ketone testing kits. While kits can be purchased at drug stores and pharmacies, you can also ask your healthcare provider for a prescription or recommendations. Make sure to follow the instructions on the labels, as testing methods may vary with different brands.

Although the most accurate way to check if you are in ketosis is to test your blood, blood tests are expensive and unrealistic to do regularly. Urine ketone testing strips are by far the cheaper and more convenient method.

Who is a good candidate for the ketogenic diet?

The ketogenic diet is a recognized medical treatment for children and some adults with seizure disorders who have not responded to two different anti-seizure medications. Specific seizure disorders with multiple reports in the medical literature of benefits from the ketogenic diet include the following:

For people with certain other seizure disorders, the diet has also been suggested to be of benefit.

As a weight-loss tool, there is not adequate evidence to suggest that this diet is superior to other weight-control plans and may be associated with long-term risks or nutritional deficiencies.

What are foods to avoid with the ketogenic diet?

Since the keto diet is a low-carb diet plan, foods to avoid with the ketogenic diet include all carbohydrate sources, including both refined and unrefined products. Not only sugars but also whole-grain carbohydrates are not allowed.

Foods to avoid include:

  • All bread and cereals
  • Pasta
  • Cookies and baked goods
  • Rice
  • Processed foods (canned soups, all desserts, and all types of candy)
  • Starchy vegetables like corn and potatoes
  • Fruits and their juices

Can I drink alcohol on the keto diet?

While alcohol isn't prohibited on a keto diet, that doesn't mean you can indulge as much as you like. Even keto-friendly or low-carb alcoholic drinks contain almost 7 calories per gram. You still have to account for these calories while planning your keto meals so you don't ruin your diet. Vodka and some specifically brewed "low carb" light beers used in very moderate amounts and only occasionally may not ruin your keto diet.

What foods are included in the ketogenic diet?

As discussed previously, the ketogenic diet includes high-fat foods and proteins and restricts carbohydrates. Since there is no one approved ketogenic diet, recommended foods, and meal plans may differ.

Table. Keto Diet: Foods to Eat Anytime Chart
Category Foods
Healthy Fats
  • Grass-fed butter
  • Ghee
  • Coconut oil
  • MCT oil
  • Extra virgin olive oil
  • Flax, chia, and hempseed oil
Proteins
  • Grass-fed meat such as beef, lamb, goat, veal, and venison
  • Organic poultry such as turkey, chicken, quail, pheasant, hen, goose, and duck
  • Free-range organ meats such as liver
  • Cage-free eggs including egg yolks
  • Wild-caught fish including tuna, trout, anchovies, bass, flounder, mackerel, salmon, and sardines
Nonstarchy Vegetables
  • Leafy greens such as dandelion, beet, collard, mustard, turnip, arugula, broccoli rabe, endive, escarole, fennel, radicchio, romaine, sorrel, spinach, kale, and chard
  • Cruciferous veggies such as broccoli, cabbage, brussels sprouts, and cauliflower
  • Celery, cucumbers, zucchini, chives, leeks, and olives
  • Fresh herbs
  • Slightly higher-carb veggies such as asparagus, mushrooms, bamboo shoots, bean sprouts, bell peppers, sugar snap peas, water chestnuts, radishes, jicama, green beans, and tomatoes
Fat-based Fruit
  • Avocados
Fermented Foods
  • Kefir, yogurt, sauerkraut, kimchi, natto, miso, and kvass
Nuts and Seeds
  • Nut butter and seed butter
  • Chia seeds and flaxseeds
  • Almonds, walnuts, cashews, sunflower seeds, pistachios, chestnuts, and pumpkin seeds
Drinks
  • Water
  • Bone broth

Should people take supplements while on the ketogenic diet?

The keto diet is a restrictive dietary pattern that involves avoiding various groups of nutritious foods including fruits, whole grains, and legumes. Since nutritional deficiencies are a risk factor with any ketogenic diet plan, it is important to work with a healthcare provider, including a nutritionist or dietitian, to ensure that all nutritional requirements are met. In some cases, this may involve taking vitamin or mineral supplements.

Some of the nutritional supplements that may be needed while on a keto diet include:

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Is the ketogenic diet safe? Health Benefit and Risks

The ketogenic diet has been shown in controlled studies to be effective in children and adults who have failed two lines of standard anti-seizure medication. However, it is not safe for use in people with certain genetic conditions that affect the metabolism of fatty acids. Nutritional deficiencies are a risk for any severely restricted diet, and in 2008 there was a report of two cases of sudden cardiac arrest in children who had been on the ketogenic diet for three years. Impairments in cardiac function may be due to a deficiency in the mineral selenium from following the diet. Support from a dietitian or nutritionist may be required to help ensure that these and other potential nutrient deficiencies are addressed.

As a weight-loss measure, while there is some evidence to suggest that a ketogenic diet can be effective for weight control, there are also definitive health risks and complications associated with this low-carb, high-fat type of diet.

Some of the positive effects of the diet that have been described in addition to weight loss include:

  • Decreased food cravings due to the high-fat content decrease in the levels of hormones that stimulate appetite
  • Fat loss and an increase in calories burned

In some people, short-term following of a ketogenic diet has shown improvements in:

Overall, the health benefits of a ketogenic diet include:

  • Improved metabolism
  • Better hunger control
  • Improved muscle mass
  • Increased weight loss
  • Better blood sugar control 
  • Improved blood pressure
  • Reduced risk of cardiovascular diseases (due to improvements in various parameters including blood cholesterol, inflammatory markers, and blood pressure)
  • Lowered insulin resistance
  • Better control of seizures in some cases

Furthermore, the extreme carbohydrate restriction of the keto diet may cause symptoms including:

It has also been proposed that the long-term side effects of this keto diet may include:

  • Osteoporosis
  • Increased risk for kidney stones
  • Gout
  • Increased low-density lipoprotein (bad) cholesterol
  • Risk of hypoglycemia (low blood sugar levels) in people on antidiabetic medications
  • Poor gut health
  • Worsening of chronic kidney disease
  • Mineral and vitamin deficiencies
  • Binge eating

Currently, it remains unknown if the potential benefits of the keto diet for weight loss outweigh the health risks. It is recommended to eat whole foods, such as non-starchy vegetables, while on a keto diet to obtain adequate vitamins, minerals, and other antioxidants. Avoid eating processed foods to reduce any health risks. If you have certain health conditions such as eating disorders, pancreatic or liver disease, or chronic kidney disease, it is better to consult your doctor before you begin with a keto diet.

What are the complications of the ketogenic diet?

Ketosis flu (keto flu) is a group of side effects that individuals might encounter when they start the keto diet.

What causes ketosis flu?

Carbs are the body's principal energy source. On the keto diet, an individual lowers their carb consumption significantly, which causes the liver to deliver glucose for energy instead, of utilizing its stores. As a result, the liver cannot create sufficient glucose to cope with the energy requirements, resulting in the body breaking down fatty acids, which form ketone bodies. This process is called ketogenesis. Body tissues then use ketone bodies as fuel, and the body enters a condition of ketosis.

The decrease in blood sugar levels results in low insulin levels in the blood. There is an increased elimination of sodium, potassium, and water through urine causing dehydration and electrolyte imbalance. Insulin is likewise associated with moving glucose to the brain. Before the brain begins to utilize ketones for energy, it will have less fuel. This will happen for a few days at the beginning of the eating regimen before blood glucose gets back to standard levels.

What are the symptoms of ketosis flu?

Ketosis flu symptoms are generally minor, occur in the initial few days to a week of starting the diet, and usually present only for a couple of days to a couple of weeks. These side effects emerge as the body adapts to working with fewer carbohydrates and enters a condition of ketosis.

While certain individuals might change to a ketogenic diet with no incidental effects, others might encounter ketosis flu and the following symptoms:

Can ketosis flu be prevented?

The symptoms of ketosis flu can be prevented or reduced in severity in the following ways:

  1. Staying hydrated: A keto diet can make you shed water stores quickly and increase the risk of dehydration. This is because glycogen (a type of stored carb in the body) binds to water in the body. At the point when dietary carbs are decreased, glycogen is utilized and water is discharged. Staying hydrated can assist with side effects, such as exhaustion and muscle squeezing.
  2. Avoiding strenuous activity: While exercise is important for remaining healthy and keeping body weight under control, strenuous activities ought to be avoided while experiencing keto flu symptoms. Exhaustion, muscle cramps, and stomach upset are normal in the initial seven-day stretch of following a ketogenic diet, so it could be a smart idea to give the body some rest. Once the body is accustomed to the keto diet, it is okay to resume all types and intensities of exercise.
  3. Adequate rest: Lack of sleep causes levels of the stress hormone cortisol to rise in the body, which can negatively impact mood and make keto flu symptoms worse. Thus, adequate rest and sleep are important to reduce keto flu symptoms.
  4. Ensure you are eating sufficient fat (and carbs): Shifting to an exceptionally low-carb diet can make one desire food varieties that are limited to the ketogenic diet, such as bread and pasta. Eating sufficient good fat, the essential fuel source on the ketogenic diet will help reduce such cravings and keep one feeling satiated.
Medically Reviewed on 1/9/2024
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