The keto diet is what you could call "trendy." It's been one of the most popular diets for weight loss for several years and boasts a host of celebrity followers, including Halle Berry, Megan Fox, Kourtney Kardashian, Adriana Lima, and more. But unlike many fad diets, the keto diet has a storied history—it actually dates back to the '20s, when it was first developed as an epilepsy treatment, and has been scientifically supported and thoroughly researched for decades.
In a nutshell, it's a high-fat, extremely low-carb diet, but it isn't that simple. Cutting out carbs essentially forces your body to subsist off of a non-carbohydrate fat-based fuel derived from ketones. Once you've successfully made this transition, "Your body burns fat without sacrificing any muscle—your basic low-fat diet can't say the same," summarizes our sister site Byrdie. Considering the complexity of the diet, we tapped Molly Devine, RD, LDN, and advisor to KetoLogic, a helpful carb counter tool for those on the diet, for more information. For starters, we asked her what actually happens to your body when you go on the ketogenic diet.
"You should be prepared for the transition into a ketogenic state," she told MyDomaine. "This often comes with a temporary loss of energy, body aches, brain fogginess, often referred to as the 'keto flu.' This often causes people to abandon this diet, assuming it isn't working for them. However, this period typically only lasts two to four days, and symptoms can be lessened with the help of an expert to guide you through this stage. As you begin the full transition into ketosis, the fog lifts, energy is restored at a much greater level than before, and most people find that they have shed several pounds of body weight."
She specifies that, in order to reach this state of ketosis, you must cut out all carbohydrates (this stealthy carb counter can help), ease up on the protein, and eat the right types of fat. "Fruit is a carbohydrate! The only exception here is the avocado, which is mainly fat. I recommend all fruit to be removed in the first month, and then slowly introduce low-sugar fruits such as berries," she explains.
"You can eat more fat, but the type of fat you eat does matter. I encourage people to look at the quality of their food sources and the body will thank you. Aim for grass-fed beef and dairy (butter), free-range chicken and eggs, wild-caught fish, avocados, coconut oil, etc." Finally, she adds, "This isn't a low-carb, high-protein way of eating. Fat needs to be your primary fuel source, and that means finding pure-fat sources that don't include protein. Your body will convert excess protein into glucose for fuel, and this will spike insulin, preventing ketosis."
While the first sign that your body is burning ketones for energy (instead of carbohydrates) is a noted increase in energy and mental clarity, a host of positive health changes transpire over time. This is what you can expect when going on the keto diet long-term, according to Devine:
Improved mental clarity and focus. "Your brain loves ketones and much prefers them to glucose for fuel. This is why people report clearer thinking while in a ketogenic state, and this way of eating is used therapeutically in patients with epilepsy, Parkinson's, and other cognitive disorders."
Decreased hunger and cravings. "Hunger and cravings are drastically reduced because the high dietary fat intake keeps you sated while the ability to burn excess body fat for fuel provides the body with a steady stream of energy."
Reduced inflammation. "Systemic inflammation is reduced by the avoidance of refined carbohydrates and sugar, and reduction in insulin production, which improves symptoms in autoimmune conditions such as auto-immune thyroid, rheumatoid arthritis, and IBD."
Reduced excess body fat. "Most people experience initial weight loss in the first few weeks on this diet due to a large amount of water weight loss from the depletion of glycogen stores and inflammation in the body from excessive carbohydrate intake. Depending on the individual, this can be up to 10 to 15 pounds." Keep in mind that "if calories remain high, you may be in ketosis and may not gain weight, but weight loss will be hard."
Improvements in insulin resistance. "Individuals with insulin resistance elevated blood glucose levels, and type 2 diabetes often see a reduction in blood glucose levels and often are able to reverse these conditions."
Improved gut health. "Gut health is often improved by the avoidance of refined carbohydrates and sugars. This leads to less IBS/D symptoms, such as bloating, gas, diarrhea, and constipation."
Regulation of hormonal balance. "By avoiding dietary carbohydrates, there is a reduction in insulin spikes (the body's natural response to increased glucose), which helps to regulate other hormones in the body. Women also find that irregular menstrual cycles return to normal and individuals suffering from acne tend to see clearer skin."
Paoli A, Rubini A, Volek JS, Grimaldi KA. Beyond Weight Loss: A Review of the Therapeutic Uses of Very-Low-Carbohydrate (Ketogenic) Diets. Eur J Clin Nutr. 2013;67(8):789-96.doi:10.1038/ejcn.2013.116
Gershuni VM, Yan SL, Medici V. Nutritional Ketosis for Weight Management and Reversal of Metabolic Syndrome. Curr Nutr Rep. 2018;7(3):97-106.doi:10.1007/s13668-018-0235-0