What are ketones?

Ketones or keto acids are compounds produced by the liver as an alternative form of energy when the body’s glucose (sugar) levels are low.

Triketone –Acetoacetate (AcAc), β-Hydroxybutyric acid Acid (BB) and Acetone – Produced in the liver from free fatty acids (FFA). When fasting or sleeping and exercising for long periods of time, the body continuously produces small amounts of ketone bodies as a source of energy.

Ketosis occurs when ketone production increases due to a decrease in carbohydrates and an increase in fatty acids. For example, people who follow a strict ketogenic diet (a very low-carb diet) rely on ketones for energy.

However, in people with certain health conditions, such as type 1 diabetes, high levels of ketones can lead to diabetic ketoacidosis (DKA), which can be life-threatening if not treated immediately.

Learn more about ketone formation, ketone testing, and what these levels mean.

What are ketones?

After fasting or following a very low-carb diet for a period of time, the body is deprived of glucose and insulin levels drop, which forces the body to burn fat for fuel from ketones.

As a result, large numbers of acetyl-CoA molecules lead to the formation of keto-beta-hydroxybutyrate, acetoacetate, and acetone in a process called ketosis.

ketone formation

When the body gets enough carbohydrates or can utilize stored carbohydrates (from glycogen), it uses them to produce glucose, the body’s preferred energy source.This process is called glycolysis and glycogenolysis.

Glucose can also be produced through a process called gluconeogenesis, which produces glucose from non-carbohydrate sources such as lactate.

However, when the body is starved of carbohydrates or glucose and has no stores of any kind, 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 around 70 to 80 percent of total calories can lead to ketone body formation. The body is able to use ketones for fuel because ketones can cross the blood-brain barrier (part of the central nervous system), whereas fatty acids cannot.

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People with diabetes may also produce ketone bodies for a variety of reasons. For example, when blood sugar is elevated and insulin is lacking (such as being sick or missing an insulin dose) or when blood sugar is normal but taking an SGLT-2 inhibitor (used to help lower blood sugar).

test ketones

People with diabetes often take ketone test strips. Ketone bodies can be detected with a urine or blood test. You can test for ketones in your blood before they reach your urine. Early detection and treatment of ketone bodies in people with diabetes can reduce the risk of emergencies, so clinicians often recommend a blood ketone meter, a home test kit.

However, if you monitor your ketones for other reasons, or if you cannot afford a blood ketone meter and test strips, you can also test for ketones in urine.

ketone bodies in urine

Results range from 0 (not detected) to +4 (high amount detected). If you’re using a home test kit, you’ll dip the test strip in your urine and compare the color to the color on the bottle. Generally, any color other than beige indicates ketones in your urine.

ketones in the blood

Blood ketone meters are prescribed for people with diabetes to accurately monitor their ketone levels. Normal levels of ketones are less than 0.6 mmol/L. Any level above this indicates the presence of ketones.

Understanding Ketone Levels

Ketone levels vary from person to person. For example, dietary intake, including carbohydrate, protein, and fat intake, can affect ketone levels. Experts recommend regular measurement of ketone bodies to provide valuable feedback for personalizing your diet. Low levels of ketone bodies in healthy individuals are usually not a problem, but elevated levels of ketone bodies in people with underlying health conditions such as diabetes can be very dangerous.

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high ketone levels

High ketone levels are usually not a problem when inducing nutritional ketosis in healthy individuals because insulin regulates glucose levels and maintains normal pH levels. However, high ketone levels in diabetics are a medical emergency because it can lead to DKA.

Experts recommend that the ketones present in DKA range from 5 to 10 times the levels achieved during nutritional ketosis. DKA can present with symptoms such as thirst, fatigue, urination, stomach pain, fruity breath, shortness of breath, shallowness, vomiting, and nausea.

Nondiabetic ketoacidosis is another risk for high ketone levels. Although the condition is rarely caused by a low-carb diet, people with other health conditions or those with illnesses such as seasonal flu are at higher risk.

low ketone levels

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

For people following a ketogenic diet, ketone levels may fluctuate based on their dietary intake. If you try to establish a state of nutritional ketosis and eat too much protein, the protein will be metabolized to glucose and reduce ketone production.

Before starting any diet, discuss your dietary changes with your healthcare provider. People with type 1 diabetes, people with a history of eating disorders (abnormal eating behaviors), and people who are pregnant or breastfeeding should avoid the ketogenic diet.


When the body’s glucose levels are low, ketone bodies are formed as a source of energy. In healthy individuals without any problems with insulin function, nutritional ketosis is generally not a dangerous condition. However, in people with diabetes, the presence of ketones increases the risk of developing DKA, which can be life-threatening if left untreated.

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If you wish to achieve some 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.

VigorTip words

If you’re following a ketogenic diet to induce nutritional ketosis, you’ll want to know what your ketone levels are. Also, if you have a medical condition that requires a ketogenic diet, such as diabetes or neurological disease, you can control your ketone levels by testing them in your urine or blood. A blood ketone meter is usually preferred.

Patients with diabetes should monitor their ketone body levels when blood sugar is elevated or when they are taking SGLT-2 inhibitors and develop symptoms of DKA. If you have diabetes, make sure you can visit your healthcare team at any time of the day.

Frequently Asked Questions

  • What if my ketone levels are too high?

    If your ketone levels are too high and you have diabetes, you may have diabetic ketoacidosis. This condition can be fatal if left untreated. If you don’t have diabetes and your ketone levels are too high, your body compensates and maintains homeostasis. The long-term effects of high ketone levels are unknown and more research is needed.

  • What is Ketoacidosis?

    Ketoacidosis occurs due to acidosis, which means too much acid in the body fluids. Ketoacidosis usually occurs in people with diabetes who rely on insulin to regulate blood sugar, but can also occur during periods of starvation. The ketogenic diet is not recommended for those who are pregnant, breastfeeding, or have type 1 diabetes.

  • What does ketone smell like?

    Ketones are often thought to smell fruity or like nail polish removers. This is because they contain acetone, which gives them a sweet taste.