The ketogenic diet has become extremely popular these days, both as a fat loss diet and as a performance diet within the ultra-endurance community. For many people in the Spartan community, it can be an incredible tool that allows them to stay sixpack lean year-round while maintaining a decent amount of muscle mass and retaining the energy to run a day-long race. But if you're a newbie to the ketogenic diet, you might be wondering what it's all about. Here's your go-to guide to getting started on keto. 

What Exactly Is the Ketogenic Diet?

The human body normally uses glucose as its primary energy source. According to Elizabeth Shaw RD, the ketogenic diet is effective for fat loss because the body enters a state of ketosis, breaking down fat for fuel in the absence of carbohydrates. In this state, fat is processed into ketone bodies, which are then used for energy in place of glucose.  

Entering ketosis requires following an extremely low-carb diet, usually for several days.  Once you’re in ketosis, you still have to eat almost no carbs, although you can have a little bit of fruit or a few crackers.  

One thing people like about the ketogenic diet is it’s simplicity.  When you cut out several entire food groups, you don’t have to make very many choices about what to eat.    

Related: 5 Keto-Friendly Snacks to Fuel You Through the Afternoon

Advantages of Being in Ketosis

Once your body has entered this state, there are several advantages to being in ketosis. Research suggests that ketogenic diets produce superior fat loss results compared to non-ketogenic diets. Not that ketosis burns fat, but ketone bodies act as appetite suppressants, and because simply reducing the amount of variety in your diet will effectively limit your appetite. 

Ketosis leads to reduced systemic inflammation, which may lower the risk of some types of cancer, as well as depression. This may be why ketosis helps people maintain muscle mass while losing weight. 

Anecdotally, many people report improved focus. And in fact, there is evidence that ketogenic diets improve mental function.  

Finally, the ketogenic diet punishes you for cheating on it. When you first enter ketosis, you’ll probably suffer from the “keto flu,” a state in which you feel fatigued and unhappy for anywhere from four to twenty-four hours.  This makes getting started on keto hard, but once you’re in ketosis, it provides a powerful motivation to stick to the diet.  

Related: Ketogenic, Paleo, Fasting: Which Is Right for You?

Getting Started On Keto

Stage One: The Induction Phase

Before you enter ketosis, you can begin pre-adapting your body to using ketones by taking a raspberry ketone supplement—three to five grams a few times a day for a week or two before beginning the diet.  You may also want to use this time to gradually reduce your carbohydrate intake and learn to cook more low-carb foods.  

Once you’re ready to enter ketosis, cut out all carbohydrates other than non-starchy vegetables.  No rice, bread, beans, potatoes, pasta, crackers, or even fruit. The lower your carbohydrate intake is, the faster you’ll get into ketosis and get over the hardest part of this diet.  

In place of those foods, you’ll need to consume more fat. Start eating fattier cuts of meat, and feel free to eat lots of eggs, cheese and butter. However, it’s important to eat unsaturated as well as saturated fat, so make sure to use a lot of olive and vegetable oils in your cooking, and start eating more nuts and avocados. Overeating bacon and cheese is a common mistake on this diet.

In fact, overeating animal products and under eating plants, in general, causes a lot of nutrient deficiencies on the ketogenic diet. “There are nutrients one needs to be very cognizant of when following a keto diet, such as fiber, as well as many of the B-vitamins like riboflavin, thiamin and B6, as well folate found in carbohydrate sources,” says Shaw. While multivitamins and fiber supplements can help, a healthy implementation of the ketogenic diet must include large quantities of vegetables and even a little bit of fruit.   

That said, eat a ton of fat, and don’t worry about counting calories for now. Do, however, make an effort to consume unsaturated fats, which mostly come from plant sources.  

Protein intake should be kept moderate. Don’t make an effort to eat more of it, but you’ll naturally eat plenty of it since protein is largely found in the same foods as fats. Limit protein intake to no more than .6 grams per pound of bodyweight.    

Finally, make sure you get enough electrolytes, especially potassium and magnesium. Get a bottle of potassium salt and start sprinkling it on your food. For magnesium, consume more leafy greens, but also consider taking a magnesium supplement in the evenings.  

The induction phase typically takes three to seven days, during which you’ll need to cut back on exercise since you’ll be low on energy. If you want to get into ketosis faster, you could instead opt to fast for two days straight—this isn’t fun, but it makes the maintenance phase seem easy by comparison.  

Related: 9 Diet Tweaks to Live By to Shed Fat & Get Lean

Stage Two: The Maintenance Phase

Once you’re in ketosis, you’ll largely keep eating the same way as you did during the induction phase. However, you can be a bit less extreme about it.  

Limit carbohydrates to no more than thirty grams a day, excluding fiber. You can now start eating low-sugar fruits like berries, but you’ll need to carefully track your carb intake. Eat a ton of vegetables, and a wide variety of them—do not less this become an all-meat and cheese diet.   

Protein intake should now be raised to .8-1 grams per day per pound of bodyweight.

All remaining calories should come from fat. Start counting calories for the first two weeks—you do need to be in a caloric deficit, however this will probably be easy. If anything you may need to make an effort to eat more, which you can do by adding oils to your meals or eating calorie-dense foods like cheese and nuts.  

Related: 6 Better Ways to Snack: Common Pitfalls & Pro Tips

Once you’re settled into a routine, start gradually increasing your activity level. The pounds should start melting off, and you’ll find your energy level goes back up—often higher than it was before. If your energy level stays low, you’re almost certainly under-eating. People who have been skinny their whole lives often don’t do well on keto for just this reason.  

Low energy during workouts—particularly sprinting or weightlifting—can also be an issue due to glycogen depletion. “Learning how to properly fuel for the type of goals you have is crucial,” says Shaw. After your first month or two on the diet, you may consider having some extra carbohydrates shortly before or after your workout—this is a modified version of the diet known as the Targeted Ketogenic Diet.   

Finally, get blood work, including cholesterol and triglycerides, after a few months on the diet. For some people a ketogenic diet improves these markers, while others see them get worse.  

The ketogenic diet is an incredibly powerful tool for fat loss and performance in endurance sports. It’s tough getting started on keto, but simple to follow—and potentially beneficial—once you’re on it.

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