As mentioned, there are a few reasons why the keto diet usually equals weight-loss gold, says Keatley. For starters, people usually reduce their daily caloric intake to about 1,500 calories a day because healthy fats and lean proteins make you feel fuller sooner—and for a longer period of time. And then there’s the fact that it takes more energy to process and burn fat and protein than carbs, so you're burning slightly more calories than you did before. Over time, this can lead to weight loss.
Supplemental ketosis: This form of ketosis has recently gained momentum in the field of ketogenic dieting. Supplemental ketosis is a ketogenic state that is achieved through the ingestion of ketogenic supplements. Consuming these substances alone does not mean that an individual is “keto-adapted.” While these products can help during the keto-adaptation period, especially if one is experiencing the “keto-flu,” they will only elicit short-term increases in blood ketone levels. Exogenous ketones can acutely produce benefits similar to the ketogenic diet; however, these products are best used in conjunction with a well-formulated keto diet for beginners, or the very at least, a diet that restricts carbohydrates. The commonly used supplements on the market are medium-chain triglyceride (MCT) oil and exogenous ketones. MCT oil is a fat that, in contrast to other longer-chain fatty acids, travels straight from the intestines to the liver where it is readily metabolized. This allows for ketone production in the liver to occur faster than with other fats (long-chain fatty acids have to travel through the lymph and circulatory systems first). Exogenous ketones are synthetic substances that mimic the ketones produced in our body (endogenous ketones). Exogenous ketones can come in the form of ketone salts or ketone esters.
"You can find a lot of "fat bomb" recipes on the Internet," Wittrock says. "These are very good at satisfying your sweet tooth, and are a great way to increase fat consumption without going over on protein. Also, I'm a huge fan of salted pumpkin seeds and salted sunflower seed kernels. Believe it or not, pork rinds are also a very good keto snack."
Once “keto-adapted,” many tissues increase their capacity to utilize ketones for fuel. Some tissues even prefer to use ketones for their cellular energy needs. For instance, the heart, as well as many areas of the brain, prefers to use ketone bodies as opposed to glucose. One interesting fact is that Dr. Stephen Cunnane found that the uptake of ketone bodies in the brain is proportional to their production.[12] Additional research has also demonstrated that as uptake of ketones increases, the uptake of glucose decreases in brain tissue.[13][14] In contrast, there are certain cells that cannot use fatty acids or ketone bodies, and are considered “obligate glucose users.” Red blood cells and specific parts of the brain are obligate glucose users. Don’t stress, however, because even though you may not be consuming a lot of carbohydrates, these cells can obtain glucose through a biological process called gluconeogenesis (the production of glucose from other non-glucose materials).
One downside to a ketogenic diet for weight loss is the difficulty maintaining it. “Studies show that weight loss results from being on a low-carb diet for more than 12 months tend to be the same as being on a normal, healthy diet,” says Mattinson. While you may be eating more satiating fats (like peanut butter, regular butter, or avocado), you’re also way more limited in what’s allowed on the diet, which can make everyday situations, like eating dinner with family or going out with friends, far more difficult. Because people often find it tough to sustain, it’s easy to rely on it as a short-term diet rather than a long-term lifestyle.

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.
The nerve impulse is characterised by a great influx of sodium ions through channels in the neuron's cell membrane followed by an efflux of potassium ions through other channels. The neuron is unable to fire again for a short time (known as the refractory period), which is mediated by another potassium channel. The flow through these ion channels is governed by a "gate" which is opened by either a voltage change or a chemical messenger known as a ligand (such as a neurotransmitter). These channels are another target for anticonvulsant drugs.[7]
Lastly, if you're active, you might need to make some adjustments to take that into account. "For the first one to two weeks, temporarily reducing your exercise load can be helpful as your body adjusts to being in ketosis," he says. "Additionally, for those who have an intense workout schedule, carb cycling may be a good option." Carb cycling essentially means you'll increase your carb intake on the days you're doing exercise, ideally just two to three days per week. "While low-carb days may be around 20 to 30 grams of net carbs daily, high-carb days can range all the way up to 100 grams, although it can vary based on your size and activity level," says Dr. Axe. (Related: 8 Things You Need to Know About Exercising on the Keto Diet.)
There are numerous benefits that come with being on keto: from weight loss and increased energy levels to therapeutic medical applications. Most anyone can safely benefit from eating a low-carb, high-fat diet. Below, you’ll find a short list of the benefits you can receive from a ketogenic diet. For a more comprehensive list, you can also read our in-depth article here >
Restricting your calories may be important for some individuals depending on their goals. Additionally, it may aid in the initiation of ketosis; however, not everyone will require calorie tracking to maintain a deficit. It is not uncommon for caloric-restriction to occur inadvertently as a ketogenic diet tends to be satiating, leaving individuals satisfied with fewer calories.
Body Composition: Physical changes in the body are one of the primary reasons people are attracted to and implement low-carbohydrate diets. By definition, being in a state of ketosis means you are able to tap into the body’s fat stores, metabolizing fat for immediate energy and producing ketones for fuel. Furthermore, the ketogenic diet has been shown to reduce circulating insulin levels, which may lead to less storage of fat by the hormone insulin.[6] While both “low-carbohydrate” and ketogenic diets are effective for weight loss, studies have demonstrated that the ketogenic diet is superior.[1]
After increasing water intake and replacing electrolytes, it should relieve most all symptoms of Keto Flu. For an average person that is starting a ketogenic diet, eating 20-30g of net carbs a day, the entire adaptation process will take about 4-5 days. My advice is to cut your carbs to fewer than 15g to ensure that you are well on your way into ketosis within one week. If you are experiencing any more keto flu symptoms, double check your electrolyte intake and adjust.
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.
Many ketogenic dieters also swear by MCT oil. (MCT simply stands for medium chain triglycerides.) MCT's energy-sustaining powers can be explained as follows: When MCT oil is metabolized in the body, it behaves more like a carbohydrate than a fat. Unlike other fats, MCT oil does not go through the lymphatic system. Instead, it is transported directly to the liver where it is metabolized so it releases energy like a carbohydrate and creates lots of ketones (which can be used for fuel) in the process.
Electrolytes: To reiterate, maintaining electrolyte balances is critical on a ketogenic diet, in order to prevent side effects and the “keto-flu.” While this can be done exclusively through whole foods, some individuals may require additional sources. Sodium, magnesium, potassium, and in some cases, calcium, can all be replenished via supplementation.
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.
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If you want to slam a protein shake post-workout, that's probably fine as long as you've got room for it in your macros. But shoot for one that is very low—like, zero—in carbohydrates. Pure isolates, such as Signature 100% Whey Isolate, are extremely low in carbohydrate. If you struggle to fit fat in during the day, toss a tablespoon of olive oil in with your shake. You won't taste it, and it gives a quick 13-14 grams of fat.
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During the 1920s and 1930s, when the only anticonvulsant drugs were the sedative bromides (discovered 1857) and phenobarbital (1912), the ketogenic diet was widely used and studied. This changed in 1938 when H. Houston Merritt, Jr. and Tracy Putnam discovered phenytoin (Dilantin), and the focus of research shifted to discovering new drugs. With the introduction of sodium valproate in the 1970s, drugs were available to neurologists that were effective across a broad range of epileptic syndromes and seizure types. The use of the ketogenic diet, by this time restricted to difficult cases such as Lennox–Gastaut syndrome, declined further.[10]
Tracking protein is important for anyone who has adopted a ketogenic diet. Depending on activity level and other metabolic factors, some individuals may be able to tolerate more protein. As mentioned above, at a certain level protein can be glucogenic; so tailor it to your needs. However, we would say to lean towards more, not less, especially for older individuals trying to preserve muscle mass.
These affect your brain and spine, as well as the nerves that link them together. Epilepsy is one, but others may be helped by a ketogenic diet as well, including Alzheimer’s disease, Parkinson’s disease, and sleep disorders. Scientists aren’t sure why, but it may be that the ketones your body makes when it breaks down fat for energy help protect your brain cells from damage.

Everyone has to find their nutritional sweet spot for producing enough ketones and staying in ketosis, but “the core principle of the diet is to keep carbohydrate intake low enough, so your body continues producing ketones at elevated levels,” says Volek. “Your body adapts to this alternative fuel and becomes very efficient at breaking down and burning fat.”
It usually takes three to four days for your body to go into ketosis because you have to use up your body's stores of glucose, i.e., sugar first, Keatley says. Any major diet change can give you some, uh, issues, and Keatley says he often sees patients who complain of IBS-like symptoms and feeling wiped out at the beginning of the diet. (The tiredness happens because you have less access to carbs, which give you quick energy, he explains.)
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.
Blood Ketone Meter: Measuring ketone levels in the blood more accurately measures and indicates an individual’s metabolic state of ketosis. Similar to measuring blood glucose levels, this method also uses a blood meter and a chemo-sensitive strip made specifically to measure ketones in the blood called beta‑hydroxybutyrate (βHB). As with blood glucose measurements, a blood sample can be acquired from a finger prick. The ketone level displays on the meter within a few seconds of a sample placement on the strip.
Keto and Traumatic Brain Injury (TBI): Research involving TBI has found that upon immediate trauma to the head, the brain takes up massive amounts of glucose. However, soon thereafter, the brain becomes resistant to taking up and utilizing glucose. This damage leads to insulin resistance and inflammation of brain tissue. The anti-oxidative and anti-inflammatory properties of ketones have been shown to not only reduce inflammation but to reduce glucose uptake in the brain as well. The ketogenic diet may also be a therapeutic treatment option for those individuals who have experienced long-term ramifications of a TBI by providing ketones as an alternative fuel source that can be readily taken up and utilized by the brain following these traumas.
The ketogenic diet is indicated as an adjunctive (additional) treatment in children and young people with drug-resistant epilepsy.[26][27] It is approved by national clinical guidelines in Scotland,[27] England, and Wales[26] and reimbursed by nearly all US insurance companies.[28] Children with a focal lesion (a single point of brain abnormality causing the epilepsy) who would make suitable candidates for surgery are more likely to become seizure-free with surgery than with the ketogenic diet.[9][29] About a third of epilepsy centres that offer the ketogenic diet also offer a dietary therapy to adults. Some clinicians consider the two less restrictive dietary variants—the low glycaemic index treatment and the modified Atkins diet—to be more appropriate for adolescents and adults.[9] A liquid form of the ketogenic diet is particularly easy to prepare for, and well tolerated by, infants on formula and children who are tube-fed.[5][30]
If you need to eat more or fewer calories per day, you can adjust accordingly by simply taking out or adding a bit more of the ingredients already included in a recipe. For example, adding/removing a tablespoon of olive oil or butter will add/remove about 100 calories. If you like or dislike certain recipes, feel free to shift things around. Make sure to keep an eye on the calories so you’re still falling within an acceptable range of your daily goal.

Constipation: As mentioned above, the elimination of carbohydrates coupled with the increased release of water may lead to constipation. If this occurs, simply increasing water consumption as well as incorporating more fiber into the diet can alleviate these symptoms. Additionally, some electrolytes like magnesium can also assist with this in higher amounts.
Instead of thinking about the total carbs you’re eating, assess what those carbs provide to you. Do the majority of your carbs come from fruit and vegetables, with a payload of fiber and disease-fighting antioxidants? Fantastic. Or are you consuming them in the form of added sugars (cookies, candy, soda) or refined flour? If you are, you know what to do.
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