Keto 101: What Are Ketones — and What Is Ketosis?
By: Alison Moodie
By now you’ve probably heard about keto, the low-carb diet that promises to melt away pounds and increase energy. When you restrict carbs and load up on the right fats, you change the way your body uses energy. You go from burning glucose (aka sugar) to burning ketones for fuel. But what are ketones? And what about ketosis?
Read on for a quick primer on some keto fundementals, including the benefits of burning ketones, the different types of ketone bodies, and what it means to be in ketosis.
What are ketones?
Ketones are a type of chemical that your body makes when it starts using fat, and not carbs, for energy.
When your body can’t get glucose from carb-rich foods like bread and pasta, your liver converts fatty acids from your diet and your fat stores into ketones, an alternative source of energy.
The keto diet is one way to get your body to make ketones. On keto, you cut way down on carbs (less than five percent of your daily calories) and instead fill your plate with high-quality fats and vegetables.
Other ways to run on ketones include fasting and using up your glucose reserves by exercising.
Why are ketones a good thing?
Your body is actually built to use fat as an alternative source of fuel. For most of history, people weren’t eating three square meals a day, plus sugary snacks in between. Instead, humans would have to hunt and gather their food, and they learned to thrive when there wasn’t any food available, sometimes for days on end.
To keep going, their bodies would use stored fat for energy. Researchers are now finding that fat might be a more efficient and sustainable fuel source than sugar.
Burning ketones carries all kinds of benefits — it boosts weight loss, gives your brain instant energy, stabilizes blood sugar, lowers inflammation, and protects your heart. Learn more about the benefits of ketones and the keto diet here.
Different kinds of ketones
There are three types of ketone bodies. They are:
- Acetoacetate (AcAc): This is the first type of ketone that your body makes from fatty acids.
- Beta-hydroxybutyric acid (BHB): Acetoacetate converts into beta-hydroxybutyric acid. BHB isn’t really a ketone, based on its chemical structure, but it’s still considered part of the ketone family since it works in a similar way to the others. Fun fact: Brain Octane oil, a purified form of MCT oil, is a precursor of BHB.
- Acetone: A byproduct of acetoacetate, acetone is the least abundant ketone in the blood. It exits the body through the breath or the urine.
You’ll produce more of each type the longer you fast or restrict carbs.
What about ketosis?
Ketosis simply means your body is using ketones, and not carbs, for energy. You can get into ketosis by following the keto diet. That means eating less than 50 grams of net carbs a day. You’re in ketosis when your ketone levels measure 0.8 millimoles per liter. Learn more here about how to test your ketone levels.
Are there risks to being in ketosis?
If you eat primarily fat and meat, all the time, you may start to feel lousy. Now everyone is different, and some people thrive when they’re in a permanent state of ketosis. But for most people, periodically upping their carb intake helps make the diet more sustainable. That’s where cyclical ketosis comes in. On a cyclical keto diet, you eat more clean carbs on one day of the week, to keep your body systems that need some carbs running smoothly. Learn more about cyclical ketosis here.
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