Ketogenic diets

When considering a diet for Type 1 diabetes, it is entirely up to the individual to decide what works best for their situation. This site is an informational resource for a very low carbohydrate lifestyle. 


A very low carbohydrate and a ketogenic lifestyle are the same for practical purposes. Specialists will argue with the fine detail. Nevertheless, ‘very low carb’ and ‘ketogenic’ are interchangeable when discussing lifestyles. 

A Standard Diet or Normal Diet is the same diet recommended by nearly all governments worldwide, with some inter-country variations. But they all use the same evidence and unsurprisingly come to the same conclusions. The conclusion is that fat is bad because it causes heart disease. So, a low-fat diet is recommended. Because of this conclusion, the percentage of fat removed from the diet is replaced by carbohydrates. It can be seen immediately that even though the recommendations consciously reduced fat, they did not make recommendations to consciously increase the carbs. The increase in carbs was just a filler to make the figures up to 100% 

So 300g of carbs, the recommended daily intake, is a non-scientific figure. It is the recommended carbohydrate intake in current guidelines. The macronutrient recommendations for a Standard Diet according to a BBC revision guide for school examinations are:

  • Total carbohydrates – 50% with no more than 5% from free sugars.
  • Total fat – no more than 35% with no more than 11% from saturates.
  • Protein – 15% as a secondary source of energy.
  • These are taken from Dietary Reference values. There are some variations around this, and some special interest charities recommend different levels. But it is generally accepted that a normal diet is based on the above numbers.
  • Low Carb has a value of 130g of carbs a day or less (often rounded to 150g). So, roughly a quarter of energy comes from carbohydrates in this diet. Often protein recommendations remain at 15%, so the fat will make up the shortfall in this diet. The low carb value was an attempt to define the minimum carbohydrate needed for brain health. It was calculated that the brain needs 500 calories a day of energy to keep going. It is a remarkable energy requirement as the brain consists of just 5% of the body’s weight, yet it consumes 20% of the energy. When this number was calculated, this was equivalent to 520 calories (one gram of carbs supplies 4 calories of energy, so 130g of carbohydrate). It was thought that the brain had an obligatory need for glucose at the time. It was also believed that this needed to be supplied from food directly. This is incorrect. The body can make sufficient glucose for all of its needs by using protein and fat and does not require the consumption of carbohydrates to meet the needs of the brain, which we now know can use fuels such as ketones. The only use nowadays for the 130-150g  figure is to compare research outcomes based on agreed definitions.  It also happens to be a rough figure (at the top-end) that many clinician experts on low carbohydrate metabolism will informally agree is a reasonable amount of carbs to start with when managing a metabolic condition such as prediabetes or diabetes (100g per day is probably a better figure to aim for).

Very low carbohydrate and ketogenic diets reduce carbohydratess to less than 50g per day. Ketogenic is often defined as 30g per day, even 20g per day. So around 10% of energy is from carbohydrates, 15% from protein and 75% from fat.

This carbohydrate level is the minimum possible to consume on a mixed diet containing vegetables. There are carbohydrates in the leaves of vegetables that are released during cooking. It is called cellulose. 50g of carbs will only supply 50x4calories =200 calories per day of energy. So that is less than ten calories per hour and is insignificant. Individuals with Type 1 diabetes will immediately see that this is tiny, especially considering that ‘in-house- the body can make at a minimum 180g of glucose from metabolic processes. (This is what long-acting insulin is used for, to counteract the glucose produced by the body’s metabolism plus some protein and fat in the food (module MB1). If one consumes  2000 calories per day, just 200 calories are produced from 50 g of carbohydrates; 90% of energy will come from fat and protein, but mostly fat. The result of fat-burning is a molecule called a ketone. Therefore, a very low carbohydrate diet generates ketones. It is ketogenic. Ketosis is often called a starvation diet.  Starvation will result in ketosis if fewer calories are consumed than required. However, the ketogenic diet here is not calorie-restricted. It is a carbohydrate-restricted diet. Calories are unrestricted within reason, although in practice, most people unintentionally consume fewer calories because of the satiating effect of protein and fat. Natural nutritional, healthy ketosis. It does not increase the risk of ketoacidosis.

Consuming minimal carbohydrates will require a very small insulin bolus for meals. But individuals will still require roughly the same amount of long-acting or basal insulin to cover the body’s glucose production. Tiny insulin doses lead to small errors, leading to increased safety. It is popularly called ‘The Law of Small Numbers’.

Some people can eat the recommended amounts of carbohydrates and thrive on them. The figures from the National Diabetes Audit for England and Wales suggest that this is around 1 in 20 based on the numbers achieving an HbA1c of less than 48mmol/mol ( 6.5%) on the assumption that they are consuming a Standard Diet. Others thrive on intermediate levels of carbs. Research indicates that the lower the carbs, the lower the HbA1c.

This site is going to address very low-carbohydrate diets. References to very low carb and keto are the same thing for practical purposes. Both terms are used to avoid confusion when reading other articles. It does not need to be complicated.