The optimal ketone range for weight loss is 0.5 to 3 millimoles per liter (mmol/L). To achieve this, carb intake needs to be dramatically reduced.

The ketogenic (keto) diet is a low carb, high fat diet that aims to keep your body in ketosis. This is a metabolic state in which you burn fat as your main source of fuel rather than carbs.

For many people, being in ketosis can help improve blood sugar levels, reduce appetite, and maintain muscle mass — all of which may contribute to weight loss.

Keep reading to learn more about the target ketone levels for weight loss and how to achieve and measure them.

After completely eliminating carbs, it may take your body 2 to 3 days to burn through its carb stores, which are stored in your liver and muscles as glycogen.

Once these carb stores are depleted, you’ll start producing acid compounds called ketones. These are created when your body uses dietary fat or stored body fat for energy. This process is known as metabolic switching.

At that point, you may have detectable levels of ketones in your blood. Blood ketone levels while on the keto diet typically range from 0.5 to 3 mmol/L.

These are the optimal levels for nutritional ketosis, the state in which your body uses stored fat for energy instead of glycogen, or carbs.

Is nutritional ketosis the same as diabetic ketoacidosis?

No, diabetic ketoacidosis is a condition that only occurs in people with diabetes. It’s characterized by extremely high levels of blood ketones alongside high blood sugar levels.

Blood ketone levels in ketoacidosis are usually much higher than those of nutritional ketosis. A 2022 study found that the cut-off level for ketoacidosis was 8 mmol/L.

Ketoacidosis is often accompanied by symptoms like increased thirst, dizziness, diarrhea, and needing to urinate more often. Nutritional ketosis doesn’t usually cause any symptoms and is safe for most people.

To achieve optimal ketone levels, you must restrict your carb intake. The macronutrient ratio for total calorie intake on a keto diet is typically:

  • Fat: 55% to 60%
  • Protein: 30% to 35%
  • Carbs: 5% to 10%

So, if you’re on a 2,000-calorie diet, this would equal 25 to 50 grams (g) of total carbs per day.

Your body will not start to produce ketones on its own until it burns through your glycogen stores, which it will not do unless you cut off its supply of dietary carbs.

Once you shift into ketosis, your body can produce ketones for energy from either dietary fat or stored body fat.

Can ketone supplements help?

Some research has found that ketone supplements, known as exogenous ketones, can help raise your ketone levels even if you’re still eating high amounts of carbs.

However, no studies to date have shown that ketone supplements alone lead to weight loss.

A 2017 study found that they may help reduce appetite, which can promote weight loss. A 2023 review also found that ketone supplements, in combination with resistance training, impacted muscle metabolism, the process by which muscles convert glycogen into energy for movement.

But one goal of entering ketosis for weight loss is to burn your stored body fat rather than supplemental ketones.

You can measure your ketone levels at home or get them measured in an outpatient clinic, pharmacy, or other medical location.

The most reliable way to measure your ketone levels is through a blood test.

At home, you can use a blood ketone meter. These devices work similarly to blood sugar meters. You use a lancet to prick your finger and a blood testing strip to collect a small blood sample from your fingertip. You then insert the strip into the device, which it reads and provides a result.

Some blood sugar meters also have ketone level meters. If you have diabetes, a doctor may recommend using this test to regularly monitor your levels to help prevent diabetic ketoacidosis.

Your body produces three types of ketones, but most blood ketone meters check for beta-hydroxybutyrate, which is the most prevalent type in blood

There’s some disagreement among researchers about the best time of day to test ketone levels. You should pick a time and consistently test at that time to get the most accurate readings.

When you last ate appears to be a major contributing factor to your ketone levels, so it’s best to test your ketone levels after a fasting period or 3 hours after eating a meal.

Urine and breath testing

You can also check to see whether you’re in ketosis by using urine test strips or a breath test. These methods are less accurate than a blood test, but they’re easier to use and typically less expensive.

Urine tests include test strips that you dip in your urine. The strips change color based on the presence of the ketone acetoacetate, which is the most common ketone in urine.

The darkness of the strip indicates the extent to which you’re in ketosis. The results may be inaccurate if you’re dehydrated.

Breath tests measure the amount of the ketone acetone in your breath in parts per million (ppm). Reliable breath testing devices are fairly expensive and slightly less accurate than blood testing, but they’re painless and don’t require the purchase of extra supplies like lancets or strips.

Breath acetone levels of around 9 ppm, and even higher in some instances, may indicate nutritional ketosis.

How often to test

Although you can test daily if you want to, it’s unnecessary. Plus, the cost of test strips can add up quickly. In fact, you don’t have to test your ketone levels at all to lose weight effectively and safely on a keto diet.

That said, consider measuring your ketone levels daily for a few days after starting keto to ensure that you reach nutritional ketosis, and then once a week while on the diet to ensure that you’re remaining in ketosis.

For some people, checking their ketone levels may provide a source of encouragement or motivation to stick with the diet.

Alternatively, some people may test more frequently to see how their bodies respond to certain foods or a change in their carb intake.

If you want to test often, urine testing strips are the least expensive, although they’re also the least accurate.

While the keto diet may help support weight loss, there could be some risks associated with it. Some short-term side effects may include:

  • nausea
  • constipation
  • vomiting
  • headache
  • fatigue
  • dizziness
  • insomnia

In many cases, these symptoms will get better within a few weeks. However, the keto diet has also been associated with more severe health conditions, such as:

  • muscle loss
  • nutrient deficiencies
  • kidney stones
  • heart disease

It’s important to speak with a healthcare professional or a registered dietitian before starting the keto diet for weight loss. They can help you determine the best meal plan for you.

Many people have found weight loss success using the keto diet.

Nutritional ketosis is defined as blood ketone levels of 0.5 to 3 mmol/L, which also represents the optimal ketone range for weight loss.

To achieve these levels, you need to significantly restrict your carb intake.

Using a blood ketone meter is the best way to check your ketone levels, but checking these levels is not necessary to lose weight on keto.