The newest buzzword to hit the diet world seems to be keto — which refers to the high-fat, low-carb ketogenic diet. With claims that you can eat all the fat you want, never feel hungry again, lower your blood sugar if you have type 2 diabetes, and even boost your athletic performance, the diet promises something for everyone.

But what exactly is the ketogenic diet, and is the weight loss program right for you? Let’s take a closer look before you attempt to make over your eating habits and lifestyle.

What Is the Ketogenic Diet Exactly?
The ketogenic diet is based on the principle that by depleting the body of carbohydrates, which are its primary source of energy, you can force the body to burn fat for fuel, thereby maximizing weight loss. When you consume foods that contain carbohydrates, the body converts those carbohydrates into glucose, or blood sugar, which it then uses for energy. (1)

Because glucose is the simplest form of energy for the body to use, it’s always used for energy before your body turns to stored fat for fuel. (1)

On a ketogenic diet, the goal is to restrict carbohydrate intake so that the body must break down fat for energy. When this occurs, fat is broken down in the liver, thereby producing ketones, which are by-products of your metabolism. These ketones are then used to fuel the body in the absence of glucose. (2)

How Do You Follow the Ketogenic Diet?
There are several types of the keto diet, but essentially, to achieve a state of ketosis, you have to severely reduce the amount of carbs you eat. (You can use this ketogenic calculator to create a custom food plan.) Data suggest the average American man over age 20 consumes 47.4 percent of his daily calories from carbs, and the average American woman over age 20 consumes 49.6 percent of her daily calories from carbs. (3) But in the classic ketogenic diet, which was originally used for the management of seizure disorders, 80 to 90 percent of calories come from fat, 5 to 15 percent come from protein, and 5 to 10 percent come from carbohydrates.

A modified version of the ketogenic diet, which allows you to eat protein more liberally — at 20 to 30 percent of your total calories — with the same carbohydrate restriction, is the more commonly used version of the diet today. Some of the aims of the latest version of the ketogenic diet are weight loss, weight management, and improved athletic performance.

An In-Depth Look at Ketosis: The Fat-Burning Mechanism That Makes the Keto Diet Work
The ketogenic diet for weight loss is based on the idea that driving the body into ketosis will maximize fat loss. Ketosis is a normal metabolic process that occurs when the body does not have enough glucose stores for energy. When these stores are depleted, the body resorts to burning stored fat for energy instead of carbs. This process produces acids called ketones, which build up in the body and can be used for energy. (2)

How Do You Know If You’re in Ketosis?
To figure out whether you’re in a state of ketosis, check your urine for ketones. You can purchase ketone strips online or from a retail pharmacy. A strip that tests positive for ketones will indicate you have reached a state of ketosis. (2)

Many people associate elevated ketones with a diabetic medical emergency known as ketoacidosis, but nutritional ketosis associated with a ketogenic diet and diabetic ketoacidosis are very different.

What Are the Potential Health Risks and Benefits of the Keto Diet?
If you search online for the term “keto diet,” you’ll see that the health claims associated with the ketogenic diet are numerous. But before you give this diet approach a try, it’s important to know what the science suggests about how it may affect your health. Namely, you’ll want to be aware of potential keto diet dangers.

Risk: You May Suffer Fatigue and Other Symptoms As a Result of the Keto Flu
One of the most common side effects of starting the ketogenic diet is the “keto flu.” This term describes the often unpleasant, fatigue-inducing symptoms that occur as the body adjusts from a high-carbohydrate to a low-carbohydrate diet. During the keto flu, the body’s stored glucose begins depleting, and the body starts adapting to producing and utilizing ketones as energy. (2)

Symptoms of the keto flu include headache, fatigue, dizziness, sleep problems, heart palpitations, cramps, and diarrhea. These side effects usually lessen and eventually resolve in about two weeks. (2) But to lessen the effects of any discomfort, simply consider slowly transitioning onto a ketogenic diet rather than rushing to change your eating habits. By slowly lowering your carbohydrate intake, while gradually increasing your intake of dietary fat over time, you can transition with less of a negative impact and potentially prevent the keto flu.

Risk: You May Experience Constipation If You Don’t Eat Enough Fruits and Veggies
The removal of many grains and fruits with such a large emphasis on fats can bring about its own set of gastrointestinal side effects. Keto constipation and diarrhea aren’t uncommon. “If not done properly — with most of your carbohydrates coming from fiber-rich vegetables — you may not be getting enough fiber, which can lead to constipation,” says Chris Mohr, PhD, RD, a sports dietitian based in Louisville, Kentucky, and co-owner of MohrResults.com. (5)

Risk: You Could Develop Potentially Dangerous Nutrient Deficiencies
Further, eliminating food groups can be problematic. “Ketogenic diets are often low in calcium, vitamin D, potassium, magnesium, and folic acid, which over time can lead to nutrient deficiencies if the diet is not planned carefully,” adds Marie Spano, RD, CSCS, who is based in Atlanta.