Editor’s note: This story was originally published on May 8, 2023. It has been updated.

If you’ve seen tomatoes used as buns or cucumber slices for sandwich bread or riced cauliflower instead of rice, then it’s possible you’ve encountered the ketogenic diet, which is also known as the keto diet.

The keto diet is one that’s low on carbohydrates and high on protein and fats.

Here’s a deeper look into what the keto diet is, the possible benefits and risks of the diet and what the latest research says about eating keto.

What is the keto diet?

The keto diet is a way of eating that’s low on carbohydrates and high on fat. That’s why you’ll see some keto social media influencers stop using hamburger buns made out of flour and instead turn to tomato slices. According to Harvard Health Publishing, the diet tries to get a person into ketosis and use ketone bodies as fuel.

This means to eat keto, a person would have to eat more fat in their diet and less carbohydrates. Harvard Health Publishing said, “Because the keto diet has such a high fat requirement, followers must eat fat at each meal. In a daily 2,000-calorie diet, that might look like 165 grams of fat, 40 grams of carbs, and 75 grams of protein. However, the exact ratio depends on your particular needs.”

Typically, a person will need to eat 20 to 50 grams of carbohydrates a day to get into the ketosis state, per the Cleveland Clinic, depending on a person’s needs. This means the bulk of a person’s diet would be low starch vegetables, cheese, meat, butter and fat, eggs and foods similar to this.

The keto diet has been talked about in connection with the Atkins diet. According to the Mayo Clinic, a cardiologist named Robert C. Atkins made the Atkins diet in the 1960s. It’s a low carbohydrate diet which a person follows in phases. One of the main differences between keto and Atkins, per Healthline, is on Atkins, a person gradually increases their carbohydrates after being on the diet and the keto diet involves a person staying at the same level.

Who made the keto diet?

William Banting, a funeral director, is sometimes credited with devising the keto diet in the 1860s as a way for him to lose weight. According to Insider, Banting tracked and shared his daily meals in a booklet. The keto diet wasn’t used in clinical practices until the 1920s.

James W. Wheless said doctors in the 1920s started using the keto diet as a way to treat children with epilepsy. The diet is now used for some chronic conditions like Type 2 diabetes or polycystic ovarian syndrome.

What foods do you eat on a typical keto diet?

A typical keto diet will include foods which fit the bill of being low in carbohydrates and high in fats. Foods like salmon, beef, chicken, cheese, leafy greens, broccoli, zucchini, nuts, seeds, cream, butter, olive oil, avocados and eggs are some examples of foods commonly eaten on a keto diet.

What foods aren’t allowed on keto?

Technically, any food that isn’t too high in carbohydrates is allowed, but since carbohydrate limit is so low, eating a couple pieces of bread along with some fruit could result in someone not reaching ketosis.

Some foods which would have to be limited or eliminated on a keto diet include flour, bread, grains, baked goods, chips, high sugar fruits, potatoes, corn and other foods higher in carbohydrates.

Potential benefits of keto

Some of the benefits of keto include weight loss and blood sugar regulation, per Healthline. There’s also some evidence it may help with cholesterol.

Potential risks of keto

There are some potential risks associated with the keto diet. UChicago Medicine said, “The keto diet could cause low blood pressure, kidney stones, constipation, nutrient deficiencies and an increased risk of heart disease. Strict diets like keto could also cause social isolation or disordered eating. Keto is not safe for those with any conditions involving their pancreas, liver, thyroid or gallbladder.”

Another potential risk is what’s called keto flu. Harvard Health Publishing said keto flu can start a couple days after starting keto. They said, “Headache, foggy brain, fatigue, irritability, nausea, difficulty sleeping, and constipation are just some of the symptoms of this condition, which is not recognized by medicine.”

Latest research on keto

Last week, a report from the American Heart Association ranked the keto diet low in terms of its impact on the heart. The Washington Post reported, “But they generally require limiting a lot of “healthy” carbs that align with the heart association’s dietary principles, like beans, whole grains, starchy veggies, and many fruits. And they typically include a high intake of fatty meats and foods rich in saturated fat.”