Dr. Anthony Gustin is a board-certified sports chiropractor, functional medicine practitioner, entrepreneur, podcast host, and founder of Perfect Keto.
When you’re following the ketogenic diet, your body switches into a state of ketosis. That means that your body will start to run off of molecules called ketones, as opposed to glucose from carbohydrates.
Many people find it useful to measure ketone levels, whether from your blood, breath, or urine. But knowing more about each ketone type and what each does can help when it comes to ketone measurement and maintaining a state of ketosis.
There are three types of ketones, but this article is about one — acetoacetate. So, what is acetoacetate and how exactly does it fit into ketosis? Read on to find out.
Acetoacetate and Ketosis
For most people, the primary energy source for the body is glucose. Glucose from carbohydrates is easily broken down, circulated through your bloodstream, and shuttled into your cells for energy.
When you eat carbohydrates like bread, pasta, sugar, fruits, or starchy vegetables, your body breaks it down into glucose, uses that glucose for energy, or stores it for later as glycogen. Glycogen is just stored glucose and it hangs out mostly in your liver and muscles, waiting to get liberated for use.
Ketosis happens when you cut your carb intake a lot and replace those calories with dietary fat and protein. Then, your body makes a metabolic shift that breaks down fatty acids for fuel instead of glucose.
So, once you’re in ketosis, you can use both fatty acids and ketones as fuel.
What are Ketones?
Once you’re in a state of ketosis, your body starts to make ketones via your liver.
And ketones are molecules that your cells and brain happily use as fuel in the absence of glucose.
There are three primary ketones, or ketone bodies, that can be detected in your bloodstream during ketosis:
Your body creates acetoacetate first. Then, BHB is created from acetoacetate, and acetone is created incidentally as a byproduct of acetoacetate.
Acetoacetate is converted into BHB, which is the rich source of energy for the brain we care about most. This process of converting fatty acids to ketone bodies is essential because your brain is not able to efficiently use fatty acids for fuel. Ketones, however, can cross the blood-brain barrier and provide your brain with the energy it needs to function.
The Function of Acetoacetate
Now that you know what acetoacetate is, it’s time to learn its function.
Ketones are the key to the benefits of being in ketosis. Ketone bodies can make up to 70% of your brain’s energy and up to 50% of the energy used for fueling your body’s tissues.
Both acetoacetate and BHB transport energy from your liver to other body tissues.
For example, a lot of acetoacetate is converted to BHB, which will then shuttle energy to your brain. This is so important because normally fatty acids themselves can’t easily cross the blood-brain barrier.
Typical Acetoacetate Levels in Ketosis
When someone has a low carbohydrate intake or is fasting, they typically have blood ketone levels of between 0.5 millimoles of BHB per liter (mmol/L), which is considered mild ketosis, and 5 mmol/L, which is very deep ketosis.
Your blood ketone concentration depends on the amount of carbohydrates and protein consumed and how long you have been eating a ketogenic diet.
For most people, blood ketone levels will rise above 1 mmol after eating keto for a few weeks. If you are eating what you think is “keto” but are not in ketosis, then your diet is not “keto” and you need to adjust your macronutrients.
Having your ketone levels in this range means your body is in ketosis and is burning fat for fuel, which has many health and performance benefits.
Most people begin a ketogenic diet with weight loss as the goal, but that’s just the tip of the iceberg, and they stay for how good it makes them feel.
Benefits of ketosis can include:
- Burning of your body’s fat stores for energy (which promotes weight loss and reduces fatigue)
- Less hunger, therefore less need to count calories
- Steady blood sugar levels from little to no intake of refined carbs (say goodbye to sugar crashes and brain fog)
- Better results and less inflammation may help if you have acne[*]
- Improved triglycerides and cholesterol levels[*]
- Better regulation of hunger hormones and insulin[*]
Testing for Acetoacetate
To determine whether or not you’re in nutritional ketosis, it’s important to monitor the ketones present in your body. Thankfully, it’s fairly easy to detect acetoacetate.
When your body is in ketosis and ketone bodies are produced, excess ketones will “spill over” and excrete from the body in different ways. There are three main types of tests you can do for measuring ketone levels:
Acetoacetate is released from the body through the urine, so naturally, urine testing is the best method for measuring its levels. (BHB is found in blood, and acetone in the breath.)
Urine testing can be done by peeing on a urine strip, which then changes color to indicate ketone level. These are very affordable and can usually be purchased at your local pharmacy. There are certain companies that make urine strips specifically for testing ketones too.
However, keep in mind that sometimes urine strips aren’t a reliable method for measuring acetoacetate levels, especially if you’ve been in ketosis for a while.
This is because your body becomes more efficient at using acetoacetate and turning it into beta-hydroxybutyrate over time. Also, it’s impossible to account for the variable of hydration accurately. The more hydrated you are the more diluted your urine is.
Personally, I have had numerous occasions where I pee on a strip to test acetoacetate and see no ketones, then get bummed because I’m apparently not in ketosis. But then I do the gold-standard blood test for BHB and sure enough, I have tons of ketones pumping through my body, they just aren’t in my urine.
The kidneys begin to adapt to the changes and become more efficient at reabsorbing acetoacetate, so over time you might not see as much of these ketones spilling over into your urine — even though they are indeed present in the body.
It’s actually a great sign if urine testing shows low levels of acetoacetate but blood tests show high levels of BHB. It means you’re deeply keto-adapted!
Plus, other factors can affect the results, such as your level of hydration and electrolytes in the body.
Is Acetoacetate Safe?
There are many common misconceptions surrounding ketosis and high ketone levels. Many medical professionals are taught that ketosis is harmful because it’s confused with diabetic ketoacidosis.
Diabetic ketoacidosis (DKA) is a dangerous condition that can occur in those with type 1 diabetes who have a lack of insulin, either from not making enough or not injecting enough.
DKA can also occur in alcoholics if they’ve been binge-drinking for a prolonged period of time without consuming carbohydrates. In ketoacidosis, ketone blood levels might rise above 10-25 mmol/L, lowering the pH level of the blood. Those are much higher levels than the 5mmol/L maximum we typically find on the keto diet.
Remember that DKA is not the same as nutritional ketosis that occurs as a result of a ketogenic diet, which is a safe and healthy way to benefit overall health, lose excess weight, and burn fat while maintaining sustained energy and steady blood sugar levels.
And, as you now know, acetoacetate plays a key role in this beneficial process.
The Takeaway: Acetoacetate is Safe
- Is the first step in the process where your body breaks down fat into ketone bodies.
- Is important because it is the precursor to beta-hydroxybutyrate, which is a vital energy carrier when we are in ketosis.
- Can be tested with urine strips. (However, overall the best way to test your ketogenic diet is by testing BHB levels in the blood.)
- Is indeed safe.