What Are Ketones?


After fasting or following a very low carbohydrate diet for some time, the body is deprived of glucose and insulin levels are lowered, which forces the body to burn fat for fuel from ketones.

As a result, an abundance of the molecule acetyl-CoA leads to the formation ketones—beta-hydroxybutyric acid, acetoacetate, and acetone—in a process known as ketogenesis.

Ketone Formation

When the body is low on carbohydrates or glucose and does not have any in storage, it forms ketones to use as energy. Strictly limiting carbohydrate intake to less than 50 grams or even 20 to 30 grams per day and increasing fat intake to about 70% to 80% of total calories can cause ketone formation. The body is able to use ketones as fuel because they cross the blood-brain barrier (part of the central nervous system) and fatty acids do not.

Ketones can also be created in people with diabetes for a variety of reasons. For example, they can form in people when blood sugars are elevated and they are lacking insulin (as in times of illness or missed insulin doses) or in people with normal blood sugars who are ill and take SGLT-2 inhibitors (prescription medications used to help lower blood sugar).

Testing Ketones

People with diabetes are often prescribed ketone testing strips. Testing for ketones can be done with urine or blood tests. You can detect ketones in the blood before they reach the urine. Early detection and treatment of ketones in people with diabetes can reduce the risk of an emergency, therefore clinicians usually recommend a blood ketone meter, an at-home test kit.

However, if you are monitoring your ketones for other reasons, or you cannot afford a blood ketone meter and test strips, you can also test for ketones through the urine.

Ketones in Urine

Results range from 0 (not detected) to +4 (high amount detected). If you are using an at-home testing kit, you will dip your test strip into your urine and compare the color to the color on the bottle. Typically, any color other than beige is an indication that there are ketones in your urine.

Ketones in Blood

Blood ketone meters are prescribed to people with diabetes to monitor their ketone levels accurately. A normal level of ketone is below 0.6 mmol/L. Any level higher than this, indicates ketones are present.

Understanding Ketone Levels

Ketone levels vary from person to person. For example, dietary intake, including carbohydrates, protein, and fat intake can influence ketone levels. Experts recommend regular ketone measurements to provide valuable feedback to personalize diets.

 Low levels of ketones in healthy individuals usually are not a problem, but elevated ketone levels in people with underlying health conditions, such as diabetes, can be very dangerous.

High Ketone Levels

High ketone levels are typically not a problem when inducing nutritional ketosis in healthy individuals, because insulin is able to regulate glucose levels and a normal pH level is maintained. However, high ketone levels in people with diabetes is a medical emergency as it can result in DKA.

Experts suggest that the range of ketones present in DKA is fivefold to tenfold greater than the levels achieved during nutritional ketosis. DKA can present with symptoms such as increased thirst, fatigue, urination, stomach pain, fruity breath, rapid, shallow breathing, vomiting, and nausea.

Nondiabetic ketoacidosis is another risk of having high ketone levels. Although this condition is rarely caused by low-carbohydrate diets, people with other health conditions or those who experience illness such as seasonal flu are at higher risk.

Low Ketone Levels

The human body produces a small number of ketones after a period of not eating or fasting. This is not an indication that the body is utilizing ketones for fuel. However, in people with diabetes, low levels of ketones or trace amounts of ketone, with high glucose levels, may indicate that a person needs more insulin.

For people following a ketogenic diet, levels of ketone can fluctuate depending on their dietary intake. If you are trying to establish a state of nutritional ketosis and are eating too much protein, protein will be metabolized into glucose and reduce ketone production.


Ketones are formed as a source of energy when the body is low on glucose. In healthy individuals who do not have any issues with insulin function, nutritional ketosis is usually not a dangerous condition. However, in people with diabetes, the presence of ketones can increase the risk of DKA, which can be life-threatening if not treated.

If you are looking to achieve a level of nutritional ketosis, you should know that the long-term effects of this diet are not well understood, and you may need additional nutritional support.

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