Ketones in the body are natural chemicals your body makes when it burns fat for energy. Most of the time, this process is completely normal. However, when ketone levels get too high, they can become a serious health concern — especially for people with diabetes. This article explains what ketones are, how they form, what causes high levels, and when you should speak with a healthcare provider.
What Are Ketones in the Body?
Ketones are a type of chemical called ketone bodies. Your liver produces them when your body breaks down fat for fuel. This happens when there is not enough glucose (sugar) available for energy.
Think of glucose as your body’s first choice for fuel. When glucose runs low — due to fasting, a low-carb diet, or diabetes — your body switches to burning fat instead. Ketones are the by-product of that fat-burning process.
There are three main types of ketone bodies your body produces:
Acetoacetate — the first ketone produced during fat breakdown
Beta-hydroxybutyrate — the most abundant ketone in the blood
Acetone — a volatile substance also used industrially as a solvent; it is the ketone responsible for the fruity or nail-polish smell on the breath
Acetone is actually the same chemical found in nail polish remover. However, when your body makes it naturally in small amounts, it is simply a normal part of metabolism. The trouble starts when levels rise too high.
How Does the Body Produce Ketones?
The Role of Fat Metabolism
Your body is always breaking down nutrients for energy. Normally, carbohydrates provide glucose, and glucose powers your cells. When carbohydrate intake drops or insulin is lacking, your body shifts to burning stored fat.
The liver breaks fatty acids down into ketone bodies. These ketones then travel through the bloodstream and are used as fuel by the brain, muscles, and other organs. This process is called ketogenesis.
When Is Ketone Production Normal?
Small amounts of ketones in the body are completely normal. For example, your body naturally produces low levels of ketones overnight while you sleep and fast. This is nothing to worry about in healthy individuals.
People following a ketogenic (keto) diet deliberately push their bodies into a state called ketosis. In ketosis, the body relies mainly on fat — and therefore ketones — for energy. Many Canadians follow this type of diet for weight management or blood sugar control, though it is always worth discussing with your family doctor first.
What Causes High Ketone Levels?
Ketone levels rise when the body burns more fat than usual over a sustained period. Several conditions and lifestyle factors can trigger this.
Diabetes and Insulin Deficiency
The most medically significant cause of high ketones in the body is diabetes — particularly Type 1 diabetes. Without enough insulin, cells cannot absorb glucose from the blood. As a result, the body acts as though it is starving and begins breaking down fat rapidly.
This can lead to a dangerous condition called diabetic ketoacidosis (DKA). In DKA, ketone levels become so high that the blood turns acidic. DKA is a medical emergency. According to Health Canada, diabetes affects over three million Canadians, making this a very relevant concern across the country.
Fasting and Low-Carbohydrate Diets
Extended fasting or following a very low-carbohydrate diet causes the body to burn fat for fuel. This raises ketone levels. In healthy people without diabetes, this rarely reaches dangerous levels.
However, if you are fasting for medical reasons or following a strict keto diet, it is a good idea to monitor how you feel and speak with your doctor about any concerns.
Prolonged Exercise
Intense or prolonged physical activity can deplete glucose stores quickly. Your body then turns to fat metabolism, which raises ketone production. This is usually temporary and not harmful in healthy individuals.
Illness and Infection
When you are sick, your body is under stress. Fever and infection can speed up metabolism and reduce appetite. This combination can raise ketones in the body, especially in children or people with diabetes.
Alcohol Consumption
Heavy alcohol use can trigger a condition called alcoholic ketoacidosis. This happens when alcohol disrupts normal metabolism, leading to a build-up of ketones. It can occur even in people without diabetes and requires prompt medical attention.
Symptoms of High Ketone Levels
Recognising the signs of elevated ketones is important. Catching it early can prevent a minor issue from becoming a medical emergency.
Common symptoms of high ketone levels include:
Fruity or acetone-like smell on the breath
Nausea or vomiting
Stomach pain or cramping
Excessive thirst and frequent urination
Fatigue and weakness
Confusion or difficulty concentrating
Rapid or laboured breathing
Flushed skin
If you or someone you know with diabetes experiences these symptoms, do not wait. Seek emergency care immediately. DKA can become life-threatening within hours. You can learn more about warning signs from the Mayo Clinic’s guide to diabetic ketoacidosis.
How Are Ketone Levels Tested?
Urine Ketone Testing
The most common way to check for ketones is a urine test. You can buy ketone urine test strips at most Canadian pharmacies without a prescription. These strips change colour to indicate ketone levels. They are simple, affordable, and widely available.
People with Type 1 diabetes are often advised to test their urine for ketones when blood sugar is high or when they feel unwell. Your diabetes care team can guide you on when and how often to test.
Blood Ketone Testing
Blood ketone meters are also available in Canada. They give a more precise reading than urine strips. Some blood glucose monitors can also measure ketones using a special test strip.
Blood ketone testing is generally recommended for people with diabetes who need more accurate monitoring. Talk to your family doctor or diabetes educator about the best option for your situation.
Understanding Your Results
Ketone levels are usually measured in millimoles per litre (mmol/L) for blood tests. As a general guide:
Below 0.6 mmol/L — normal range
0.6 to 1.5 mmol/L — slightly elevated; monitor closely
1.5 to 3.0 mmol/L — high; contact your doctor promptly
Above 3.0 mmol/L — very high; seek emergency care immediately
For urine tests, results typically show as negative, trace, small, moderate, or large. Any result of “moderate” or higher warrants a call to your doctor or a visit to a walk-in clinic.
Ketones and the Keto Diet: What Canadians Should Know
The ketogenic diet has grown in popularity across Canada in recent years. This high-fat, very low-carbohydrate diet intentionally raises ketones in the body to promote fat burning.
For most healthy adults, mild ketosis from a keto diet is not dangerous. However, for people with diabetes, kidney disease, or other chronic conditions, the diet can carry risks. Furthermore, the long-term effects of sustained ketosis are still being studied.
If you are thinking about trying a ketogenic diet, speak with your family doctor or a registered dietitian first. They can help you decide if it is appropriate for your health needs. You can also find evidence-based nutrition information from Healthline’s overview of the ketogenic diet.
It is also worth noting that the keto diet is not covered under most provincial health plans as a medical treatment. However, if your doctor prescribes dietary therapy for a specific medical condition, a registered dietitian consultation may be covered under your provincial plan.
When to See a Doctor
You should speak with your family doctor if you have diabetes and are regularly finding ketones in your urine or blood. Even moderate levels that are not an emergency still deserve medical attention.
Visit a walk-in clinic if you are experiencing symptoms like nausea, vomiting, stomach pain, or unusual fatigue — especially if combined with increased thirst or frequent urination. These can be early warning signs of rising ketone levels.
Call 911 or go to your nearest emergency department right away if you or someone else has:
Very high blood ketone levels (above 3.0 mmol/L)
Difficulty breathing or very rapid breathing
Confusion, extreme weakness, or loss of consciousness
Uncontrolled vomiting that prevents keeping fluids down
Diabetic ketoacidosis is a medical emergency. Do not drive yourself to the hospital if you feel confused or very unwell. Call for help.
As always, this article is for general information only. Please consult your doctor or a qualified healthcare provider for advice tailored to your personal health situation.
Frequently Asked Questions About Ketones in the Body
What does it mean if I have ketones in my body?
Having ketones in the body means your body is burning fat for energy instead of glucose. Small amounts are normal, especially during fasting or low-carb dieting. However, high levels — particularly in people with diabetes — can signal a serious condition called diabetic ketoacidosis.
What are the symptoms of high ketones?
Common symptoms of high ketones include a fruity smell on the breath, nausea, vomiting, stomach pain, extreme thirst, and fatigue. In severe cases, high ketones in the body can cause confusion and rapid breathing. If you experience these symptoms, contact a healthcare provider promptly.
Can you have ketones without having diabetes?
Yes, you can have ketones in the body without having diabetes. Fasting, prolonged exercise, a ketogenic diet, or heavy alcohol use can all raise ketone levels. In healthy individuals without diabetes, this is usually not dangerous, but very high levels should always be evaluated by a doctor.
How do I check my ketone levels at home in Canada?
You can check ketone levels at home using urine test strips, which are available at most Canadian pharmacies without a prescription. Blood ketone meters are also available and give more accurate results. Ask your family doctor or diabetes educator which method is best suited to your needs.
Are ketones dangerous on a keto diet?
For healthy adults, the mild rise in ketones in the body caused by a ketogenic diet is generally not dangerous. However, people with diabetes, kidney disease, or other health conditions face greater risks. Always speak with your family doctor before starting a ketogenic diet.
What is the difference between ketosis and ketoacidosis?
Ketosis is a mild, controlled increase in ketones in the body, often seen with fasting or a keto diet — it is generally safe in healthy people. Ketoacidosis, particularly diabetic ketoacidosis (DKA), involves dangerously high ketone levels that make the blood acidic and require emergency medical treatment. The two conditions are very different in severity.
Key Takeaways
Ketones in the body are produced when the body burns fat for energy instead of glucose.
Small amounts of ketones are normal. High levels can be dangerous, especially for people with diabetes.
Acetone is one of three types of ketone bodies — it causes the fruity breath smell associated with high ketone levels.
Diabetic ketoacidosis (DKA) is a life-threatening emergency. Know the warning signs.
You can test ketone levels at home using urine strips or a blood ketone meter, available at Canadian pharmacies.
Speak with your family doctor before starting a ketogenic diet, particularly if you have any existing health conditions.
If you have moderate or high ketone levels or are experiencing symptoms, contact your family doctor, visit a walk-in clinic, or call 911 in an emergency.
Always consult a qualified healthcare provider for advice that fits your individual health needs.
