Now that ketogenic diets have become popular, many keto hybrid diets have sprung up, including plant-based versions. (One is “ketotarian,” which is predominantly plant-based but includes the option of eggs, ghee, and fish and shellfish.) While this approach can be healthy, Hultin cautions against trying keto as a vegan. “Because you can’t eat beans or lentils on a ketogenic diet, and nuts and seeds are even limited due to their carbohydrate content, you’re really just left with some tofu and will need to rely on low-carb protein powder,” she says. There is a good possibility this won’t pan out. “I don’t see this as a sustainable diet due to the extreme restrictions,” she says.
Keto-adaptation occurs as tissues maximally increase their capacity to utilize ketone bodies for fuel. As glucose metabolism slows and fatty acid breakdown ramps up, ketones are synthesized and increasingly utilized for fuel. After a few weeks or months of increasing ketone and fat utilization, the body adapts to these new fuel sources. In addition to increased fat breakdown and ketone synthesis and utilization, keto-adaptation is associated with decreased and stabilized blood glucose levels.
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. While both “low-carbohydrate” and ketogenic diets are effective for weight loss, studies have demonstrated that the ketogenic diet is superior.
Positive science on ketosis coupled with personal successes passed by word-of-mouth have driven more people to explore the ketogenic diet, says Volek. More recently, the keto diet hints at having a promising therapeutic role in cancer, Alzheimer’s, Parkinson’s and polycystic ovary syndrome (PCOS). Research is still early in many areas, but Volek suspects there will more definitive answers on the wider scope of the diet’s benefits within the next decade.
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. Additional research has also demonstrated that as uptake of ketones increases, the uptake of glucose decreases in brain tissue. 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).
The ketogenic diet is a mainstream dietary therapy that was developed to reproduce the success and remove the limitations of the non-mainstream use of fasting to treat epilepsy.[Note 2] Although popular in the 1920s and '30s, it was largely abandoned in favour of new anticonvulsant drugs. Most individuals with epilepsy can successfully control their seizures with medication. However, 20–30% fail to achieve such control despite trying a number of different drugs. For this group, and for children in particular, the diet has once again found a role in epilepsy management.
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.
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. But does that mean it will happen? Not necessarily, particularly if you're just an occasional supplement user.