When dietary carbohydrate is broken down into the energy substrate glucose, thereby raising blood glucose levels, the pancreas is stimulated to secrete insulin (the hormone that stores fat and inhibits ketone production). However, when carbohydrate intake is restricted, insulin remains suppressed, and the body’s primary fuel source shifts from glucose to fat, priming the body to enter a state of ketosis. When fat oxidation/breakdown is increased to a certain extent, ketones are made in the liver through a process known as ketogenesis (i.e., keto + genesis = ketone formation). When carbohydrate intake is restricted, blood glucose and insulin levels decrease, which allows fat stores to be broken down rapidly for energy. Most cells in the body can utilize either fatty acids or ketones for fuel, including the brain, which has shown to be more efficient in the presence of ketones rather than glucose.
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.
“Your liver produces ketones all the time, but the rate depends on carbohydrate and protein intake,” says Jeff Volek, Ph.D., R.D., a professor of human sciences at Ohio State University. When the majority of your diet is made up of of carbs and protein, ketogenesis slows. Replacing carbs and protein with fat will put your body into ketosis, thus ramping up ketone production. Essentially, you're burning fat instead of carbs for energy. This process takes about three days to induce.
Those issues can be part of what's known as the “keto flu,” Warren says. Other side effects of the keto diet, all of which are tied to carb withdrawal, can include lightheadedness, nausea, mental fog, cramps, and headaches, in addition to tiredness. Luckily, the keto flu doesn't usually last more than a week—which is coincidentally about when people start to see the number on the scale go down, says Warren.
By cutting carb intake significantly, we can drastically reduce insulin resistance, the precursor to type 2 diabetes. In addition, low carb diets, along with exercise, can be very effective at helping alleviate the symptoms and progression of type 2 diabetes. Beyond that, ketosis itself is appetite-suppressing, meaning your hunger will naturally check itself, increasing your caloric deficit and making you lose fat even faster. Read more about ketosis: What Is Ketosis, and How Long Does It Take to Get into Ketosis?
^ Ketogenic "eggnog" is used during induction and is a drink with the required ketogenic ratio. For example, a 4:1 ratio eggnog would contain 60 g of 36% heavy whipping cream, 25 g pasteurised raw egg, saccharin and vanilla flavour. This contains 245 kcal (1,025 kJ), 4 g protein, 2 g carbohydrate and 24 g fat (24:6 = 4:1). The eggnog may also be cooked to make a custard, or frozen to make ice cream.
For patients who benefit, half achieve a seizure reduction within five days (if the diet starts with an initial fast of one to two days), three-quarters achieve a reduction within two weeks, and 90% achieve a reduction within 23 days. If the diet does not begin with a fast, the time for half of the patients to achieve an improvement is longer (two weeks), but the long-term seizure reduction rates are unaffected. Parents are encouraged to persist with the diet for at least three months before any final consideration is made regarding efficacy.
After initiation, the child regularly visits the hospital outpatient clinic where they are seen by the dietitian and neurologist, and various tests and examinations are performed. These are held every three months for the first year and then every six months thereafter. Infants under one year old are seen more frequently, with the initial visit held after just two to four weeks. A period of minor adjustments is necessary to ensure consistent ketosis is maintained and to better adapt the meal plans to the patient. This fine-tuning is typically done over the telephone with the hospital dietitian and includes changing the number of calories, altering the ketogenic ratio, or adding some MCT or coconut oils to a classic diet. Urinary ketone levels are checked daily to detect whether ketosis has been achieved and to confirm that the patient is following the diet, though the level of ketones does not correlate with an anticonvulsant effect. This is performed using ketone test strips containing nitroprusside, which change colour from buff-pink to maroon in the presence of acetoacetate (one of the three ketone bodies).