If you are new to the keto diet read our beginner's guide to keto.
What is Ketosis?
Ketosis is a metabolic state in the body in which the body burns ketones for energy rather than blood sugars. It uses these ketones as the main energy source for the body and brain. On a traditional diet, the body runs on glucose for energy. This glucose is stored in the liver and secreted into the bloodstream. You're brain and body run on this glucose, or sugar.
On a low carb diet, your body switches into ketosis mode and starts to use ketones for fuel. Ketones are an alternate source of energy from the sugar your body needs on a traditional diet. Ketones are made by the liver when fat is broken down and used for energy.
This is why low carb diets often burn fat quicker than traditional calorie-restricted diets. The three types of ketones are beta-hydroxybutyrate (BHB), acetoacetate, and acetone.
You do actually produce some ketones even when you're not on a restricted carb diet. When you do go on a low carb diet your body just shifts to make a large number of ketones to fule you. When the glucose and insulin levels decrease, as a result of the keto diet, then the liver ramps up ketone production. It's actually safe for most people to run on ketones. If you're a type one diabetic then you probably don't want to try a low carb diet (ask your doctor).
Once the ketones in your blood reach a certain level you are considered to be in nutritional ketosis. The threshold is typically considered to be 0.3 - 0.5 mmol/L.
How Long Does it Take to Reach Ketosis?
Many people are wondering just how long it takes to get into ketosis. You should note that there are other ways to enter ketosis besides low carb diets. This includes fasting. When people are fasting the body does enter ketosis. Some people have been known to produce ketones after a single overnight fast while other people can take much longer. So the short answer is that it depends? It depends on your diet and how your body responds to the diet.
Being in ketosis means that you are "fat adapted" or transforming fat into ketone for energy. So you may start to produce ketones after a short fast or a few days of eating a low carb diet. However, have you really reached ketosis? According to tests you might be over 0.03mml/l. However, we considered being in ketosis as being fat adapted.
It might take 2-4 weeks to actually become fat adapted. You really need to be fat-adapted before you start to see the amazing benefits of the keto diet. So how can you really tell if you're in ketosis and/or fat-adapted?
How Do I Know if I'm in Ketosis?
Like we said above, you want to reach a state of ketosis and stay there for 2-4 weeks to become fat adapted. How can you tell if you're in a state of ketosis? Well, there are different types of tests that you can administer to see if your blood ketone levels are high. These include strips that you urination on, breath tests, and blood tests. Many of these items can be purchased online.
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Are There Other Signs of Ketosis?
Many people don't have a ketone meter to tell if they are in ketosis. While we recommend testing it's not 100% necessary. There are some signs that will give you a hint if you are in ketosis. Here are some of the common signs that your body is entering ketosis.
- Thirst or Dry Mouth - When you're in ketosis your body tends to flush out water at a higher rate than normal. This can often lead to dry mouth or excessive thirstiness.
- Lack of Appetite - The main reason the keto diet works is that it causes you to feel full for longer. This is because your body is running on ketones and is experiencing fewer blood sugar swings that cause hunger. This is a good sign of ketosis.
- Rapid Weight Loss - Of course, this is the main reason we chose a keto diet. If you start to see the pounds melt off easily then you are probably in ketosis.
- Ketone Breath - Believe it or not, bad breath is good on ketosis.Since acetone is one of the ketones that your body produces you will often get a unique smell to your breath. A change in the smell of your breath is an excellent sign that you are in ketosis. Many people report that this goes away.
- Urine Smell - Just like your breath, the smell of urine can become very strong. This is because your body will start removing the excess ketones via urine.
Keto Flu - You may experience symptoms similar to the flu. This is known as the keto flu. This happens early on when you're body is transitioning into ketosis. This is a good sign but can feel like it's not. Don't give up. Push through the keto flu and you will be fine.
- Metallic Taste - Ketosis can give you a metallic taste in the mouth due to excess ketones. If it tastes like you're chewing on a penny that is a good sign that you're in ketosis.
The Bottom Line on Ketosis
The best way to tell if you're in ketosis is to use a ketone test. However, we recommend not worrying too much about your ketone levels. Simply follow your macros and you'll get into ketosis. Stay between 20-50g of carbs per day (ideally below 30) and eventually, you will enter ketosis. Be on the lookout for the symptoms of ketosis that we mentioned above. If you are experiencing several of those symptoms then you are probably in ketosis. If you're a person that just has to know, then you need to measure with a ketone meter. They are relatively inexpensive and will give you sure results. Keep calm and keto on!
John Ward has been experimenting with low carbohydrate diets since the early 2000s. He successfully used a low carb diet to lose 50lbs in the past and currently follows a keto diet for a variety of reasons including general health and managing mood levels.