In the 1960s, medium-chain triglycerides (MCTs) were found to produce more ketone bodies per unit of energy than normal dietary fats (which are mostly long-chain triglycerides).[15] MCTs are more efficiently absorbed and are rapidly transported to the liver via the hepatic portal system rather than the lymphatic system.[16] The severe carbohydrate restrictions of the classic ketogenic diet made it difficult for parents to produce palatable meals that their children would tolerate. In 1971, Peter Huttenlocher devised a ketogenic diet where about 60% of the calories came from the MCT oil, and this allowed more protein and up to three times as much carbohydrate as the classic ketogenic diet. The oil was mixed with at least twice its volume of skimmed milk, chilled, and sipped during the meal or incorporated into food. He tested it on 12 children and adolescents with intractable seizures. Most children improved in both seizure control and alertness, results that were similar to the classic ketogenic diet. Gastrointestinal upset was a problem, which led one patient to abandon the diet, but meals were easier to prepare and better accepted by the children.[15] The MCT diet replaced the classic ketogenic diet in many hospitals, though some devised diets that were a combination of the two.[10]
As for branched-chain amino acids, you'll find smart people who swear that they're keto-friendly, and others who don't. One of the BCAAs, valine, can be glucogenic, meaning that it can lead to glucose production and potentially contribute to leaving ketosis behind.[1] But does that mean it will happen? Not necessarily, particularly if you're just an occasional supplement user.
Quite simply, for the majority of people the answer is a resounding “yes!” Due to its high-fat nature, it is often perceived as a health risk, often deterring individuals from trying it. Despite this misconception, research has demonstrated that the ketogenic diet is safe for most people, providing you don’t have one of the following conditions (even if you have any of these conditions, the ketogenic diet may still be safe, but you would need to work very closely with your doctor):

The ketogenic diet may seem like the Jekyll to the Hyde-like low-fat craze of the 1990s. The bulk of current research finds that the middle ground between the two extremes is more beneficial for overall health. Make it easy for yourself: Eat at least two servings a week of fatty fish (salmon, sardines, mackerel) and cook with a variety of quality fats (olive oil, canola oil, avocado oil) throughout the week.
And if you can't survive without your pasta, there are plenty of products out there like Explore Cuisine's organic black bean spaghetti that give you the pasta experience without the carbs. There are also tons of keto-friendly restaurants—like Red Lobster, Olive Garden, and Texas Roadhouse—that can allow you to treat yourself to a night out without coming out of ketosis.
Thanks for trying to stick to the evidence! So often these “newer” diets and therapies are not fully researched and are of peoples opinions. As a physical therapist I try to keep up on what will help my patients. This article and website will be added to my resource list. It’s not possible to be the expert on everything, so thanks for putting out quality information.
Unfortunately, it has been ingrained into society that consuming dietary fat is detrimental to our health. Due to early “research” by individuals such as Ancel Keys, these concepts have plagued our perceptions of dietary fat for several decades. Dietary fat, when consumed alone, isn’t the culprit for bad health, but rather it is the pairing of high amounts of fat and high amounts of carbohydrates in meals (i.e., fast food) driving the issues. This high fat and carb combination has led to the many serious health problems we face today, giving rise to the quote, “Don’t blame the butter for what the bread did.”

The ketogenic diet is not a benign, holistic, or natural treatment for epilepsy; as with any serious medical therapy, complications may result.[28] These are generally less severe and less frequent than with anticonvulsant medication or surgery.[28] Common but easily treatable short-term side effects include constipation, low-grade acidosis, and hypoglycaemia if an initial fast is undertaken. Raised levels of lipids in the blood affect up to 60% of children[38] and cholesterol levels may increase by around 30%.[28] This can be treated by changes to the fat content of the diet, such as from saturated fats towards polyunsaturated fats, and if persistent, by lowering the ketogenic ratio.[38] Supplements are necessary to counter the dietary deficiency of many micronutrients.[18]
Achieving optimal ketosis hinges on finding the right balance of macronutrients (or “macros” in keto-speak); these are the elements in your diet that account for the majority of your calories, a.k.a. energy—namely, fat, protein, and carbohydrates. By the way, it’s often “net grams” of carbohydrates that are counted toward your daily intake; “net” deducts the amount of fiber in a food from its carbohydrate total.
The answer to this question is often individualized and will depend on the metabolic state of each individual. One can enter a state of ketosis after an overnight fast. However, this slight elevation may not be high enough to allow for your body to efficiently utilize these ketones as a primary fuel source. Over time, as you become more adapted, your body will consistently be producing AND utilizing ketones. For some, this could take as little as one week, however, for others, it could take several weeks to accomplish. The length of time it takes to become keto-adapted also greatly depends on the composition of the ketogenic diet utilized (i.e., 20 grams versus 50 grams of carbohydrates per day) as well as personal activity level.
If you're new to keto, watch out for hidden carbs. Generally, dairy products and nuts are a good way to meet your daily fat intake, but know that some of those items may contain more carbohydrates than you think. For example, yogurt topped with nuts may seem like a great keto-friendly snack, but a 5.3 ounce serving of plain yogurt has 12 grams of carbohydrates. Vanilla flavored yogurt has 24 grams of carbohydrates. Add an ounce of cashews, weighing in at nearly nine grams of carbs, and you’re up to 21 to 33 grams of carbs for that snack, which could knock you out of ketosis. Be sure to read nutrition labels carefully and pay careful attention to serving sizes. Track foods using a keto-specific app like Senza or KetoDiet can help you stay within your recommended daily carb intake.

The most science-backed performance-boosting supplements, such as creatine monohydrate, beta-alanine, and caffeine, are all A-OK on the ketogenic diet. So, if you take a pre-workout, you should be able to continue without issue. I would also recommend gulping down some bouillon before your session to ensure your sodium and magnesium levels are on point.

In addition, there are medical conditions that should make you think twice about starting keto — or at least talk to your doctor before trying it out. Those include people on insulin, as well as those on oral and noninsulin injectable medications for high blood sugar or high blood pressure, says Hultin. Even struggling with GI issues may be a barrier to starting. “One of the side effects of a ketogenic diet is constipation, so if that’s a struggle, there’s serious reason not to go on this relatively low-fiber diet,” says Hultin. Last consideration: If existing personal dietary restrictions require you to avoid foods like soy, eggs, nuts, dairy, or seafood, a ketogenic diet may be too limiting for you. Coming from a place of elimination in an already restrictive diet can make it incredibly tough to follow, she says.

The original therapeutic diet for paediatric epilepsy provides just enough protein for body growth and repair, and sufficient calories[Note 1] to maintain the correct weight for age and height. The classic therapeutic ketogenic diet was developed for treatment of paediatric epilepsy in the 1920s and was widely used into the next decade, but its popularity waned with the introduction of effective anticonvulsant medications. This classic ketogenic diet contains a 4:1 ratio by weight of fat to combined protein and carbohydrate. This is achieved by excluding high-carbohydrate foods such as starchy fruits and vegetables, bread, pasta, grains, and sugar, while increasing the consumption of foods high in fat such as nuts, cream, and butter.[1] Most dietary fat is made of molecules called long-chain triglycerides (LCTs). However, medium-chain triglycerides (MCTs)—made from fatty acids with shorter carbon chains than LCTs—are more ketogenic. A variant of the classic diet known as the MCT ketogenic diet uses a form of coconut oil, which is rich in MCTs, to provide around half the calories. As less overall fat is needed in this variant of the diet, a greater proportion of carbohydrate and protein can be consumed, allowing a greater variety of food choices.[4][5]

The beauty of salmon is that you can cook it with marginal interference. A simple sauce of butter, lemon juice, chopped garlic, and some salt and pepper will go a long way to enhancing the natural flavor of the salmon. Drizzle the sauce over 4-6 oz portions of fish, bake at 450F for 5 minutes per 1/2″ thickness of fish. In another bowl, toss the asparagus with olive oil, salt, and pepper, spread it out evenly on a cookie sheet, and roast in the oven at 450 for 20 minutes. Easy dinner (with leftovers if you plan ahead) that’s full of nutrition, protein, and healthy fat, while keeping your carbs low. Get the recipe and instructions
Fasting ketosis: Fasting ketosis, also referred to as starvation ketosis, played a major role in the development of the keto diet for beginners. The concept of fasting has been around for centuries and can be traced back to biblical times. By definition, fasting is the absence of caloric consumption for a period of time. This can range from several hours to several days and can have profound effects on the degree of ketosis. As the duration of the fasting increases, so does the production of ketones, and thus a deeper ketogenic state is obtained. As such, the mechanisms of ketone production are similar between fasting and dietary applications similar to keto diet for beginners, both of which result in lower and more stable levels of insulin and blood glucose accompanied by fat metabolism.
When something is popular, it’s pretty much a guarantee that people are going to come up with new or easier ways of doing it. Enter the lazy keto and dirty keto diets. With lazy keto, people try to limit their carb intake to 20 to 50 grams a day but don’t really track it; with dirty keto, people generally follow the same macronutrient breakdown as "regular" keto, but it doesn't matter where those macronutrients come from.
Keto for Alzheimer’s Disease: One characteristic of Alzheimer’s disease is insulin resistance in the brain (hence why it’s now being referred to as type III diabetes), which robs this critical tissue of energy. Limiting glucose while introducing ketones may be an effective mechanism for replenishing the energy in the tissue. The higher level of ketone production accompanied with a ketogenic diet is another example as to why this diet is superior to one that simply restricts carbohydrate intake. Additionally, Alzheimer’s disease is characterized by beta-amyloid deposition, which may also be mitigated by the implementation of a ketogenic diet.
There are theoretically no restrictions on where the ketogenic diet might be used, and it can cost less than modern anticonvulsants. However, fasting and dietary changes are affected by religious and cultural issues. A culture where food is often prepared by grandparents or hired help means more people must be educated about the diet. When families dine together, sharing the same meal, it can be difficult to separate the child's meal. In many countries, food labelling is not mandatory so calculating the proportions of fat, protein and carbohydrate is difficult. In some countries, it may be hard to find sugar-free forms of medicines and supplements, to purchase an accurate electronic scale, or to afford MCT oils.[54]
On the ketogenic diet, carbohydrates are restricted and so cannot provide for all the metabolic needs of the body. Instead, fatty acids are used as the major source of fuel. These are used through fatty-acid oxidation in the cell's mitochondria (the energy-producing parts of the cell). Humans can convert some amino acids into glucose by a process called gluconeogenesis, but cannot do this by using fatty acids.[57] Since amino acids are needed to make proteins, which are essential for growth and repair of body tissues, these cannot be used only to produce glucose. This could pose a problem for the brain, since it is normally fuelled solely by glucose, and most fatty acids do not cross the blood–brain barrier. However, the liver can use long-chain fatty acids to synthesise the three ketone bodies β-hydroxybutyrate, acetoacetate and acetone. These ketone bodies enter the brain and partially substitute for blood glucose as a source of energy.[56]
This can look different for everybody, but some popular forms of this are the 16:8 diet, where you fast for 16 hours (usually from dinnertime until a late breakfast) and eat all your food within an eight-hour span. Another is the 5:2 diet, where you eat less than 500 calories for two non-consecutive days a week and then eat normally for the rest of the week.

As for branched-chain amino acids, you'll find smart people who swear that they're keto-friendly, and others who don't. One of the BCAAs, valine, can be glucogenic, meaning that it can lead to glucose production and potentially contribute to leaving ketosis behind.[1] But does that mean it will happen? Not necessarily, particularly if you're just an occasional supplement user.