High levels of ketosis can be serious High levels of ketosis can be serious

Ketosis is a state the body may find itself in either as a result of raised blood glucose levels or as a part of low carb dieting.

Low levels of ketosis is perfectly normal.

However, high levels of ketosis in the short term can be serious and the long term effects of regular moderate ketosis are only partially known at the moment.

What is ketosis?

Ketosis is a state the body goes into if it needs to break down body fat for energy. The state is marked by raised levels of ketones in the blood which can be used by the body as fuel.

Ketones which are not used for fuel are excreted out of the body via the kidneys and the urine.

Is ketosis the same as ketoacidosis?

There is often confusion as to the difference between ketosis and ketoacidosis.

Ketosis is the state whereby the body is producing ketones. In ketosis, the level of ketones in the blood can be anything between normal to very high.

Diabetic ketoacidosis, also known as DKA, only describes the state in which the level of ketones is either high or very high. In ketoacidosis, the amount of ketones in the blood is sufficient to turn the blood acidic, which is a dangerous medical state.

When does ketosis occur?

Ketosis will take place when the body needs energy and there is not sufficient glucose available for the body.

This can typically happen when the body is lacking insulin and blood glucose levels become high.

Other causes can be the result of being on a low carb diet.

A low level of carbohydrate will lead to low levels of insulin, and therefore the body will produce ketones which do not rely on insulin to get into and fuel the body’s cells.

A further cause of ketosis, less relevant to people with diabetes, is a result of excessive alcohol consumption.

Is ketosis dangerous?

The NHS describes ketosis as a potentially serious condition, whereas a number of popular diets cite ketosis as being an essential part of weight loss.

Ketosis is described as being potentially dangerous as very high level of ketones can make the blood acidic, a state known as ketoacidosis, which can lead to serious illness in a relatively short space of time.

Maintaining relatively high levels of ketones over a long period of time, such as by being on a ketogenic diet for a long time, has had questions asked over long term safety.

A study, carried out at the John Hopkins Children’s Centre in Baltimore, USA, was conducted for up to 8 years and found ketogenic diets to be relatively safe over that period. However, these studies were carried out on patients up to 26 years old and evidence of safety over the longer term and in older groups is not so well known.

Testing for ketones

It is possible to check your blood to find out the ketone level in your blood. It is also possible to check your urine for ketones, however, the result given may only indicate the level of ketones earlier in the day.

What is a safe level of ketosis?

The presence of ketones will measured in either mmol/l or by plus signs ‘+’.

Different levels of ketones

Levels of Ketones
Level of
Under 0.6 mmol/l No signs Normal
Under 1.5 mmol/l + Moderate
1.6 to 3.0 mmol/l ++ High
Over 3.0 mmol/l +++ or ++++ Very high

General advice is to keep ketones levels low to prevent any risk of organ damage, particularly to the kidneys and liver.

If you take insulin, having ketone levels above 1.5 mmol/l (+) could represent a risk of ketoacidosis.

High or very high ketone levels may be indicated by vomiting or the presence of ketones on the breath, which may smell ‘fruity’ or reminiscent of nail polish remover.

Research has yet to produce conclusive evidence over which levels of ketones are safe to maintain over extended periods of time, such as for people on low carbohydrate or ketogenic diets.

Ketosis and low carb diets

A state of ketosis is a fairly common result of going onto a low carbohydrate diet.

As indicated above, there is no particular ketone level that has been regarded as safe over the long term.

People who choose to go onto low carb diets are often advised to keep hydrated by drinking sufficient fluids through the day.

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