You’ve likely heard the term “Ketogenic Diet” floating around the internet, or even in conversations with friends and family members who say “I’m not eating carbs” (usually touting the fact that they now eat unlimited bacon). Some people are turning to this very low carb diet approach to lose weight quickly. But what is a ketogenic diet, does it work, and how safe is it?
A ketogenic diet is a very low carbohydrate diet, meaning you consume less than 5% of your daily calories from carbohydrate. In an 1800 calorie diet, this is only 23 grams of carbohydrate per day, which roughly the equivalent to 1 and a ½ slices of bread. And don’t forget, carbohydrates are found in many foods, including fruits, vegetables, and dairy, which all count towards this daily allowance of carbohydrate.
So, what do people eat on a ketogenic diet eat? The majority of this very low carb diet is made up of foods high in dietary fat. In fact, keto-diet followers aim for roughly 75% of their calories from fat, and limited their intake of protein to about 20%. What does this look like? Each meal has a small amount of protein (meat, poultry, fish, seafood, eggs), a large amount of high fat foods (avocado, coconut oil, butter, olive oil, nuts and nut butters, bacon, egg yolks, and cheese) and a very small amount of very-low carb vegetables such as spinach, kale, broccoli, cucumbers, celery, or peppers. Most fruit, grains, beans, and starchy vegetables do not fit into this diet.
The science behind it: Simply put, very low carb diets shift your body into burning fat for fuel, rather than its preferred fuel of carbohydrate. Which means, yes, ketogenic diets may lead to weight loss, because it mimics the effect of starvation in the body. The majority of weight loss seen in the first few days is the result of water loss as your body breaks down (and eventually runs out) of stored glucose. Once it runs out of glucose, it mobilizes the body’s fat stores for energy. The process of breaking down fatty acids forms ketones- hence the name “ketogenic diet.”
Ketosis can be helpful for some people- for example, research has shown that ketogenic diets may help reduce the frequency of seizures in patients with epilepsy and may be effective for reducing specific types of brain tumors. Therapeutically, ketogenic diets may also be used to correct some metabolic diseases under the close supervision of a medical professional.
For the average healthy individual, ketogenic diets for short periods of time are generally safe but are not recommended for extended periods of time or for athletes. Very low carb diets can cause fatigue and hinder athletic performance. This means that prepping for a vacation by starting a ketogenic diet and going to the gym 5 days a week will only cause you to hit a wall. Your endurance will actually suffer, and you will likely feel tired and cranky. You may even end up sick, as carb restriction coupled with intense exercise can lead to a suppressed immune system.
If your goal is sustainable health, the solution is not to remove entire macronutrient groups from your diet. Most low carb diets do not work in the long run because of its restrictive nature. Following a diet that has you constantly focus on what you can’t have will likely make you want it more, and a slip up can cause you to overeat that “forbidden” food. Rather, focus on adding nutrients in to your diet from a variety of vegetables, fruits, legumes, lean proteins, and whole grains.
Most importantly, everyone is different. The best way to get individualized support for your nutrition goals is to meet with a qualified health professional, such as your doctor or a registered dietitian.