Although many hypotheses have been put forward to explain how the ketogenic diet works, it remains a mystery. Disproven hypotheses include systemic acidosis (high levels of acid in the blood), electrolyte changes and hypoglycaemia (low blood glucose). Although many biochemical changes are known to occur in the brain of a patient on the ketogenic diet, it is not known which of these has an anticonvulsant effect. The lack of understanding in this area is similar to the situation with many anticonvulsant drugs.
The ketogenic diet is calculated by a dietitian for each child. Age, weight, activity levels, culture, and food preferences all affect the meal plan. First, the energy requirements are set at 80–90% of the recommended daily amounts (RDA) for the child's age (the high-fat diet requires less energy to process than a typical high-carbohydrate diet). Highly active children or those with muscle spasticity require more food energy than this; immobile children require less. The ketogenic ratio of the diet compares the weight of fat to the combined weight of carbohydrate and protein. This is typically 4:1, but children who are younger than 18 months, older than 12 years, or who are obese may be started on a 3:1 ratio. Fat is energy-rich, with 9 kcal/g (38 kJ/g) compared to 4 kcal/g (17 kJ/g) for carbohydrate or protein, so portions on the ketogenic diet are smaller than normal. The quantity of fat in the diet can be calculated from the overall energy requirements and the chosen ketogenic ratio. Next, the protein levels are set to allow for growth and body maintenance, and are around 1 g protein for each kg of body weight. Lastly, the amount of carbohydrate is set according to what allowance is left while maintaining the chosen ratio. Any carbohydrate in medications or supplements must be subtracted from this allowance. The total daily amount of fat, protein, and carbohydrate is then evenly divided across the meals.
If you start at 25g of net carbs a day, you can slowly increase to 50g as you lose weight. Once you reach your goal, you can increase your carbs as you see how they affect your weight. If you eat fruit for a week and gain weight, cut back. You have to figure out what works best for you. Ketosis can be maintained with as many as 100g of carbs each day.
I have been eating this way (very low carb, high fat, protein in between) for around 3 years now. I have found that for me I can MAINTAIN quite easily at an ideal weight and eating to satiety, but in order to actually LOSE weight, I have to at least have a very small calorie deficit. And though the change is gradual, it is sustainable and quite immediate (just little by little). The amount of that calorie deficit required in order to drop excess varies a lot from one individual to the next though, I think. I am particularly intolerant to hunger, and so I cannot overly emphasize how small of a deficit I will allow for. The nice thing about that though is that the hunger is far more pleasant in the absence of carbs.
I have PCOS as well. Research a PCOS-specific diet. It often overlaps with Keto or Paleo recipes. But you have to also avoid holstein cow produced dairy products, red meat, pork, soy products (which are in almost every processed food) in addition to carbs and sugar. And absolutely avoid anything you can’t be sure doesn’t have extra hormones injected into it (like many mass-farmed meats). Vigorous exercise is also necessary to lose weight when you have PCOS (It’s much, much more difficult for us to lose weight than people with normal hormonal balances).
On a ketogenic diet, you’re generally eating a diet that’s high in fat (roughly 70 percent of your total calories come from fat), moderate in protein (about 20 percent of your calories), and low in carbohydrate (about 5 percent of calories). By limiting carbohydrates (to usually less than 45 grams for the average person), your body lacks the glucose (from carbs) that it normally uses for energy, so it eventually switches over to burning fat as its primary fuel source instead; through a metabolic process called ketosis, the liver converts the fat into fragments of fatty acids called ketones, which power the brain and other organs and tissues.
A systematic review in 2018 looked at 16 studies on the ketogenic diet in adults. It concluded that the treatment was becoming more popular for that group of patients, that the efficacy in adults was similar to children, the side effects relatively mild. However, many patients gave up with the diet, for various reasons, and the quality of evidence was inferior to studies on children. Health issues include high levels of low-density lipoprotein, high total cholesterol, and weight loss.
Variations on the Johns Hopkins protocol are common. The initiation can be performed using outpatient clinics rather than requiring a stay in hospital. Often, no initial fast is used (fasting increases the risk of acidosis, hypoglycaemia, and weight loss). Rather than increasing meal sizes over the three-day initiation, some institutions maintain meal size, but alter the ketogenic ratio from 2:1 to 4:1.