If you’ve decided to move forward in trying the keto diet, you will want to stick to the parameters of the eating plan. Roughly 60 to 80 percent of your calories will come from fats. That means you’ll eat meats, fats, and oils, and a very limited amount of nonstarchy vegetables, she says. (This is different from a traditional low-carb diet, as even fewer carbs are allowed on the keto diet.) 

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.[1] 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.[9] For this group, and for children in particular, the diet has once again found a role in epilepsy management.[1][10]
Take a multivitamin. “Because you are removing grains, the majority of fruit, some vegetables, and a significant amount of dairy from your menu, a multivitamin is good insurance against any micronutrient deficiencies,” says Jadin. Depending on what your individual overall diet looks like, Jadin says you might also need to add a calcium, vitamin D, and potassium supplement.
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.
H. Guldbrand, B. Dizdar, B. Bunjaku, T. Lindström, M. Bachrach-Lindström, M. Fredrikson, C. J. Östgren, F. H. Nystrom, “In Type 2 Diabetes, Randomisation to Advice to Follow a Low-carbohydrate Diet Transiently Improves Glycaemic Control Compared with Advice to Follow a Low-fat Diet Producing a Similar Weight Loss,” Diabetologia (2012) 55: 2118. http://link.springer.com/article/10.1007/s00125-012-2567-4.

Still, it can be hard to get enough fat when you first start this diet. Butter, nuts, coconut and olive oils, and fatty cuts of meat are all on the menu. However, don't go overboard with polyunsaturated fats like soybean, corn, or sunflower oil. Keto dieters who increase their intake of those fats often end up with gastrointestinal distress that causes them to jump ship.

^ 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).[17] The eggnog may also be cooked to make a custard, or frozen to make ice cream.[37]

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.
I eat relatively healthy and fairly low carb (I am already gluten free). I am interested in getting into Ketosis for the the health benefits, but am quite thin for a guy and don’t want to lose any weight. I look at the sample diet above and am pretty sure I would drop weight quickly (I consume about 2,500+ calories daily now). I eat 3 meals plus 2-3 snacks (snacks mostly of nuts (with raisins that would have to go), greek yogurt (would switch to plain), peanut butter, cheese and fruit (would need to reduce qty)). Would eating straight up butter be ok for additional calories also once I am in Ketosis?
In pediatric patients whose seizures could not be treated with these anti-epileptic drugs, a ketogenic diet was able to reduce seizures by more than 50% in 54% of the young patients tested, with 10% of the cohort becoming seizure-free after one year on the diet.[28] Since this study, numerous additional studies have shown this modality to be effective for children and adults with epilepsy. Results of ketogenic diet–driven studies have included 55% of patients seeing a reduction in seizures by more than 50%,[29] and 27% of patients seeing a 90% or greater reduction in seizures with many entering into complete remission.[30]
At the start of a keto diet for beginners, it is not uncommon for an individual to experience rapid weight loss. This may concern some people, but it is worth noting that not ALL weight lost is body fat. When we lower our carbohydrate intake our insulin lowers, causing us to excrete more water. Additionally, reducing carbohydrate intake causes the body to break down glycogen stores (to initially maintain blood sugar levels); glycogen is the storage form of glucose that is located in our liver and skeletal muscle. The loss of both water and glycogen accounts for most of the weight loss in the first few days. Don’t be discouraged! Soon after, total body water and glycogen levels will balance out.

Also make sure that you know what foods have mostly carbs, fat, and protein, so you can make the right choices. For instance, it’s not just bread, pasta, chips, cookies, candy, and ice cream that contain carbs. Beans may contain protein, but they’re also very high in carbohydrates. Fruit and veggies also mostly contain carbs. The only foods that don’t contain carbs are meat (protein) and pure fats, like butter and oils (including olive oil and coconut oil).

Although studies have shown that the keto diet can reduce seizures for children with epilepsy, there is no evidence indicating that keto helps with other brain disorders or improves mental cognition, according to Harvard Health Publishing. Some studies show that keto may lower blood sugar for people with type 2 diabetes, but there is not enough long-term research to determine whether it’s safe and effective for diabetics.
When in the hospital, glucose levels are checked several times daily and the patient is monitored for signs of symptomatic ketosis (which can be treated with a small quantity of orange juice). Lack of energy and lethargy are common, but disappear within two weeks.[17] The parents attend classes over the first three full days, which cover nutrition, managing the diet, preparing meals, avoiding sugar, and handling illness.[19] The level of parental education and commitment required is higher than with medication.[44]
Carbohydrates have been linked to this skin condition, so cutting down on them may help. And the drop in insulin that a ketogenic diet can trigger may also help stop acne breakouts. (Insulin can cause your body to make other hormones that bring on outbreaks.) Still, more research is needed to determine exactly how much effect, if any, the diet actually has on acne. 

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.[9] 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[19] and includes changing the number of calories, altering the ketogenic ratio, or adding some MCT or coconut oils to a classic diet.[18] 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.[19] 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).[45]
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.

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.