A ketogenic diet is a diet that is designed to bring about ketosis, the breaking down of body fat into ketones, and allow the body to largely run on ketones rather than glucose.
There are a number of ways in which ketosis can be brought about and therefore there are a number of different variants of ketogenic diet.
Because the end goal of these diets is the same, the different types of ketogenic diet usually share a number of similarities, notably in being low in carbohydrate and high in dietary fat.
The figures in this guide are for information only and are not an instruction to follow. For advice on how to put together a diet, speak to a dietitian as they will be able to give you personalised guidance based on your individual needs.
Standard Ketogenic Diet (SKD)
This is a very-low carb, moderate protein and high fat diet. It typically contains 70 to 75 per cent fat, 20 per cent protei, and about 5 to 10 per cent carbs.
In terms of grams per day, a typical standard ketogenic diet would be:
- 20-50g of carbohydrate
- 40-60g of protein
- No set limit for fat
Fat in the diet should provide the majority of calories for it to be a ketogenic diet. No limit is set as energy requirements can vary significantly from person to person.
Ketogenic diets should include a strong intake of vegetables, particularly non-starchy vegetables, as these are very low in carbohydrate.
Standard ketogenic diets have consistently shown success in helping people to lose weight, improve blood glucose control and improve heart health. 
Very-low-carb ketogenic diet (VLCKD)
A standard ketogenic diet is very-low-carb and therefore a VLCKD will usually refer to a standard ketogenic diet.
Well Formulated Ketogenic Diet (WFKD)
The term ‘Well Formulated Ketogenic Diet’ comes from Steve Phinney, one of the leading researchers into ketogenic diets.
The WFKD follows a similar blueprint as a standard ketogenic diet. Well formulated means that the macronutrients of fat, protein and carbohydrate meet the ratios of the standard ketogenic diet and therefore provide the best chance of ketosis occurring.
MCT Ketogenic Diet
This follows the outline of standard ketogenic diet but has a focus on using medium chain triglycerides (MCTs) to provide much of the fat content of the diet.
MCTs are found in coconut oil and is available as MCT oil and MCT emulsion liquids.
MCT ketogenic diets have been used to treat epilepsy because the theory is that MCTs allows people to consume more carbohydrate and protein whilst keeping in ketosis. This is because MCTs provide more ketones per gram of fat than the long-chain triglycerides that are present in normal dietary fat.
Note that MCTs can lead to stomach upset and diarrhoea if consumed largely on its own. To prevent this, it’s best to have meals with a balance of MCTs and non-MCT fat.
There is a lack of studies, however, investigating whether MCTs have wider benefits on weight loss or blood sugar. 
Calorie-restricted ketogenic diet
A calorie-restricted ketogenic diet is similar to a standard ketogenic diet except in that calories are restricted to a set amount.
Research shows that ketogenic diets tend to be successful whether calorie intake is restricted or not. This is because the satiating effect of eating fat and being in ketosis tends to help prevent over-eating in itself.
Cyclical Ketogenic Diet (CKD)
The CKD diet, also known as carb backloading, involves days in which more carbs are eate, such as five ketogenic days followed by two higher carb days.
The diet is intended for athletes which can use the higher carb days to replenish glycogen lost from muscles during workouts.
Targeted Ketogenic Diet (TKD)
The TKD is similar to a standard ketogenic diet except that carbohydrates are consumed around workout times.
It is a compromise between a standard ketogenic diet and a cyclical ketogenic diet that allows you to consume carbohydrates any day you exercise.
It is based on the concept that carbohydrate consumed before or after a physical effort will be processed much more efficiently, as the muscles’ demand for energy increase when we’re being active.
High Protein Ketogenic Diet
This diet includes more protein than a standard ketogenic diet, with a ratio of 35 per cent protei, 60 per cent fat, and 5 per cent carbs.
As with other forms of ketogenic diet, there is a lack of research into whether there are any health risks if followed for many years.