What you need to know about the ketogenic diet

Diet trends come and go, but it seems like there’s always a low-carb program in the mix. The ketogenic diet is at the top of the list right now.

The ketogenic diet, also called the keto diet, focuses on getting most of your calories from fat and some from protein, while drastically cutting carbohydrates.

We spoke to Maria Petzel, a senior clinical dietitian at MD Anderson, to learn more about the keto diet, maintaining a healthy weight, and reducing your cancer risk. Here’s what she had to say.

How does the keto diet work?

In a typical healthy diet, 45-65% of calories come from carbohydrates. With low-carb diets like the South Beach or Atkins diets, about 20-30% of your calories come from carbs. With the ketogenic diet, carbohydrates make up only 5-10% of your calories.

When your body is deprived of carbohydrates, it uses stored fat for energy instead. To do this, the liver turns the fat into acids called ketones. Those ketones are used by your muscles and tissues for fuel.

This process is called ketosis. It typically starts after three to four days of restricting carbs.

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Can the ketogenic diet help you lose weight?

Ultimately, if you lose weight on the keto diet, it’s not because of some complicated body chemistry.

The initial weight loss is water weight associated with the loss of the body’s stored carbohydrate. After that, the weight loss is the same as any diet, mostly fat.

“The key to weight loss is to burn more calories than you eat each day, no matter the source of those calories,” says Petzel. “Being in ketosis will suppress the appetite, and that may help to lower total calorie intake in general.”

 “Because of the loss of water weight, when they return to a regular diet, people find that they quickly gain back some of the weight they lost doing a low-carb diet. If they don’t continue to avoid excess calorie intake they can ultimately gain all of the weight back,” Petzel says.

Is the keto diet safe?

“Ketosis may help you lose weight, but it’s not necessarily helping your body,” Petzel says.

After a few days on the diet, you may experience fatigue, dizziness, nausea or stomach pains. Some people refer to these symptoms as the “keto flu” though it does pass.

In addition to the short-term, unpleasant symptoms that come from restricting carbohydrates, ketosis can have more serious side effects.

Too many ketones can be bad for your body. Ketosis can dehydrate you and change the chemical balance of your blood. Ketosis can be especially dangerous for people with diabetes because it can affect their insulin levels and lead to dangerously low blood sugar levels.

The long-term effects of the keto diet are less clear.

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Researchers have found mixed results of the effects of high-fat, high-protein and low-carbohydrate diets on heart health, non-insulin dependent diabetes, and other chronic diseases. Some high-fat, high-protein foods, like red or processed meats are known to increase cancer risk.

In addition, the lack of fiber in the diet can lead to constipation, which can worsen conditions like diverticulitis.

Certainly, following a diet that basically cuts out an entire nutrient category, including almost all grains, fruits and vegetables can lead to vitamin and mineral deficiencies, says Petzel.

Researchers do not fully understand the effects of a ketogenic diet on specific tumor types or treatments for those with cancer. Studies suggest that it may help control some types of tumors but promote others.

Everyone responds to ketosis differently, says Petzel, so it’s important to talk to your doctor before starting any new diet.

Focus on long-term healthy eating

Your best bet for maintaining a healthy weight is to focus on making sustainable changes to your diet.

Watch your portion sizes, and stick to mostly plant-based foods. Strive to get a balance of carbohydrates, proteins and healthy fats, and avoid processed meats.

“Tied in with exercise, these habits are more likely to help you maintain a healthy weight over a long period of time,” Petzel says. “And that can help lower your cancer risk.”