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.
^ Jump up to: a b c Clemente FJ, Cardona A, Inchley CE, Peter BM, Jacobs G, Pagani L, Lawson DJ, Antão T, Vicente M, Mitt M, DeGiorgio M, Faltyskova Z, Xue Y, Ayub Q, Szpak M, Mägi R, Eriksson A, Manica A, Raghavan M, Rasmussen M, Rasmussen S, Willerslev E, Vidal-Puig A, Tyler-Smith C, Villems R, Nielsen R, Metspalu M, Malyarchuk B, Derenko M, Kivisild T (October 2014). "A Selective Sweep on a Deleterious Mutation in CPT1A in Arctic Populations". American Journal of Human Genetics. 95 (5): 584–589. doi:10.1016/j.ajhg.2014.09.016. PMC 4225582. PMID 25449608.
As ketones levels rise in the body, the cells of heart, brain and muscles begin to use them for fuel. And once the body is using ketones as a main fuel source, there are some profound and positive health effects. Ketogenic diets are very effective for correcting cellular metabolic dysfunction. The high blood sugar of diabetes gets reversed, the seizures of epilepsy can be calmed, Alzheimers and Parkinsons symptoms are alleviated, extra weight can be lost, joint pain is diminished and so on. In other words, the ketogenic diet is not a “fad.” It is a potent regulator of metabolic derangement, and when formulated and implemented correctly, it can be extremely effective at reversing all kinds of health problems. (See this paper.)
Use fat as a lever. We’ve been taught to fear fat, but don’t! Both keto and low carb are high fat diets. Fat is our source of energy as well as satiety. The key to understand, though, is that fat is a lever on a low carb or keto diet. Carbs and protein stay constant, and fat is the one you increase or decrease (push the lever up or down) to gain or lose weight, respectively. So if your goal is weight loss, eat enough fat to be satisfied, but there’s no need to “get your fats in” once you’re satisfied.
You can have a completely smooth transition into ketosis, or…not. While your body is adapting to using ketones as your new fuel source, you may experience a range of uncomfortable short-term symptoms. These symptoms are referred to as “the keto flu.” Low-sodium levels are often to blame for symptoms keto flu, since the kidneys secrete more sodium when you’re in ketosis, says Volek. A few side effects:
If you're healthy and eating a balanced diet, your body controls how much fat it burns, and you don't normally make or use ketones. But when you cut way back on your calories or carbs, your body will switch to ketosis for energy. It can also happen after exercising for a long time and during pregnancy. For people with uncontrolled diabetes, ketosis is a sign of not using enough insulin.
This is an absolutely necessary function for basic survival. As the body can only store carbs for a day or two, the brain would quickly shut down after a couple of days without food. Alternatively it would quickly have to convert our muscle protein into glucose – a very inefficient process – just to keep the brain going. That would make us waste away quickly. It would also ensure that the human race could hardly have survived all those millennia before we had 24-7 food availability.
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.