The ketogenic diet is when people change their nutrition plan, so their bodies produce ketones. This occurs in a process called ketosis, which is when a person burns fat instead of carbohydrates as their main source of energy.
The ketogenic diet is low in carbohydrates and higher in fats. While several versions of the diet exist, a person will typically eat 3 to 4 grams (g) of fat for every 1 g of protein and carbohydrates.
The result is a diet that provides around 70% of calories from fat, 20% from protein, and 10% from carbohydrates. This is different from a traditional low-carbohydrate diet that usually involves increasing protein intake.
The Mediterranean ketogenic diet is one example of a ketogenic diet that is high in fat. It incorporates no more than 30 g of carbohydrates, 1 g of protein for every 2.2 pounds of bodyweight mainly coming from fish, and fat sources that are 20 percent saturated fat and 80 percent unsaturated fat, primarily from olive oil.
In this article, we look at the best foods to eat for people who are following a ketogenic diet. We also examine what should be avoided and what are the benefits and risks.
Fats are the biggest source of energy and calories in a ketogenic diet.
Not all fats are the same. For example, doctors do not consider trans fats to be healthful fats. These are hydrogenated fats added to foods to maintain their shelf life.
Saturated fats are a significant part of the ketogenic diet. Saturated fats are those that are solid at room temperature. The body needs some of these to promote a healthy immune system and for other body functions.
Ketogenic-friendly saturated fat sources include:
- coconut oil (0 g carbohydrate per 100 g)
- grass-fed beef (0 g carbohydrate per 100 g)
- butter from grass-fed cows (0 g carbohydrate per 100 g)
- whole milk and whole-milk dairy foods (4.88 g carbohydrate per 100 g)
Dietitians and doctors call monounsaturated and polyunsaturated fats the “good” fats.
Research shows keto diets with a higher proportion of unsaturated fats versus saturated fats have long-term benefits. These fats are liquid at room temperature, and sources of them include:
- almond oil (0 g carbohydrate per 100 g)
- flaxseed oil (0.39 g carbohydrate per 100 g)
- mackerel (0 g of carbohydrate per 100 g)
- olive oil (0 g of carbohydrate per 100 g)
- sardines (0 g of carbohydrate per 100 g)
- pumpkin seeds (8.96 g of carbohydrate per 50 seeds)
- sustainably-harvested seafood
- walnuts (13.71 g of carbohydrate per 100 g)
- wild salmon (0 g of carbohydrate per 100 g)
The ketogenic diet is not a high-protein diet. The body converts excess protein to glucose when carbohydrate intake is low, thereby restricting ketosis.
Foods that are sources of protein on the ketogenic diet tend to be the same foods that provide healthy fats.
For example, grass-fed meat products are a staple on this diet. Grass-fed meats tend to have higher levels of omega-3 fatty acids than others, which is an advantage on the ketogenic diet.
Nuts, seeds, and eggs are also ketogenic diet staples.
Seafood, especially fish and low-carbohydrate shellfish, such as shrimp and most crabs, are also on the menu.
Some shellfish also contain carbohydrates, which people on a ketogenic diet should take this into account when eating these options. These varieties include clams, mussels, oysters, and squid.
Ketogenic-recommended vegetables are of the non-starchy variety. “Starchy” vegetables contain carbohydrates and are not a part of the ketogenic diet.
Examples of non-starchy vegetables include:
- artichoke (10.51 g of carbohydrate per 100 g)
- asparagus (3.88 g of carbohydrate per 100 g)
- baby corn (18.7 g of carbohydrate per 100 g)
- broccoli (6.64 g of carbohydrate per 100 g)
- Brussels sprouts (8.95 g of carbohydrate per 100 g)
- eggplant (5.88 g of carbohydrate per 100 g)
- green beans (6.97 g of carbohydrate per 100 g)
- okra (7.45 g of carbohyrdrate per 100 g)
- onions (9.34 g of carbohydrate per 100 g)
- salad greens, such as romaine, spinach, arugula, and endive
- squash (11.69 g of carbohydrate per 100 g)
- tomato (3.89 g of carbohydrate per 100 g)
- turnips (3.39 g of carbohydrate per 100 g)
- water chestnuts (6.34 g of carbohydrate per 100 g)
Fruits are not a part of the ketogenic diet because of their higher carbohydrate and sugar content.
However, avocado is a part of the diet thanks to its high-fat content. Blackberries are also sometimes included due to their very high fiber content.
Foods that are mainly carbohydrates, such as breads and pastas, are not seen on the ketogenic diet.
Most fruit is not ketogenic-diet friendly either, as mentioned above.
The ketogenic diet is different from many traditional diet plans because it is low in carbohydrates. This can make it difficult for some people to follow. However, there are ways to eat the ketogenic diet and enjoy its benefits without feeling deprived.
Some of the steps people can take to do this include:
- Sipping on unsweetened coffee and tea instead of sodas or other high-sugar drink options.
- Adding ketogenic-approved condiments, such as yellow mustard, ketchup with no added sugar, mayonnaise, hot sauce, Worcestershire sauce, and high-fat salad dressings. All these options should not have sugar added to them.
- Cooking with no-sugar-added herbs and spices, such as basil, cilantro, cayenne pepper, thyme, salt, pepper, or chili powder.
A person should also talk to a dietitian about their individual nutritional and supplement needs on a ketogenic diet. Cutting out most carbohydrates can lead to some people not getting enough of certain nutrients.
The ketogenic diet may have made headlines in recent years for its power to help people lose weight or manage their diabetes. However, those with epilepsy have used the diet since the 1920s to reduce their seizure occurrence.
Children with epilepsy who have been resistant to traditional seizure medications may respond well to the ketogenic diet.
According to the Epilepsy Foundation, an estimated 50 percent of children on the ketogenic diet reduce their seizures by half on the ketogenic diet. An estimated 10 to 15 percent of children do not experience seizures after adopting the diet.
A child will usually continue to take their medications in addition to following the diet.
Researchers are starting to study the keto diet’s benefits for adults more and more. A 2016 review found that following a ketogenic diet promoted weight loss and improved heart health.
The diet also appeared to lower hemoglobin A1c levels, a measurement of a person’s blood sugar levels over 3 months.
Another article found that the ketogenic diet helped to suppress appetite while maintaining a steady metabolic rate, or rate at which the body uses energy over time.
The ketogenic diet involves consuming high levels of fats. As such, several side effects can occur if a person follows the diet long-term, especially if they do not eat enough fiber and vegetables.
These side effects include:
A person may also be more prone to bone fractures. For this reason, dietitians often recommend taking supplements to boost bone strength, such as vitamin D, calcium, selenium, and many of the B vitamins.
Following the ketogenic diet can initially lead to what doctors call the “keto flu,” a condition that causes feelings of dizziness, fatigue, difficulty sleeping, and constipation for a few days to several weeks. This can be avoided or shortened by supplementing with electrolytes when first starting the diet.
After this time, a person will tend to start feeling better and experience the more positive effects of the ketogenic diet. However, people must carefully watch their food intake to ensure they are getting enough calories and nutrients to support good health.
The keto diet will not suit everyone. A person should always talk to their doctor before beginning any new diet. They may also wish to consult a dietitian to ensure they are eating enough nutrients to stay healthy.