How Does Ketosis Work?
Whether or not you’re following the ketogenic diet, you’ve probably heard the word “ketosis” floating around recently. You might have a vague idea of what it means, but let’s find out how ketosis works.
What is ketosis?First, in order to understand how it works, we need to know what ketosis is. Essentially, nutritional ketosis is a metabolic state that occurs when your body is required to switch from carbohydrates to fat to use for energy. If you’re following the Standard American Diet (or another eating pattern high in carbohydrates), you shouldn’t experience ketosis (unless you are diabetic and very ill). A diet high in carbohydrates provides plenty of glucose that can be broken down for energy or stored in the liver and muscles.
How does ketosis work?Meanwhile, when following the ketogenic diet, your carbohydrate intake is severely restricted, and what glucose is available is typically used to provide the brain with energy. At first, carbohydrates stored in the body (as glycogen) can be broken down to glucose by the liver and provided to the organs and tissues that need energy the most urgently. Once the body glycogen stores have been exhausted, fatty acids in the diet are broken down to triglycerides, a process that releases ketones (acids) as a byproduct. Ketones can circulate in the blood to allocate energy – which is extremely important since some organs (including the brain) cannot break down fats for energy (but they can use ketones). As you can see, this is why the ketogenic diet is so high in fat – in order to provide as many fatty acids as possible to be used for energy. Once they have served their purpose, ketones are removed from the body in the urine. Once the body has used up all the circulating fatty acids from the diet for energy, it still needs a constant source of fuel – so body fat is targeted. Stored body fat can be broken down to fatty acids and ketones, just like fat from the diet. This is a major reason why weight loss on the ketogenic diet tends to be rapid once ketosis is achieved (but this should not be confused with the stored carbohydrate and water weight loss during the first week).
Are there different levels of ketosis?Yes! Although people tend to discuss ketosis like it’s an “on” or “off” switch, there are actually different levels, and you have two main options for determining the extent of ketosis – urine and blood testing. Breath ketone tests are also available, but much less common. Blood ketone testing In order to get a precise measurement of circulating ketones, testing your blood is typically much more reliable. After entering ketosis, most people will test their blood on a weekly basis to ensure that their levels are still appropriate to keep them in ketosis. Blood ketone testing kits are simple to use, just like blood glucose testing done by diabetics – a small drop of blood and a meter. Blood tests measure one of the most common ketones – beta-hydroxybutyrate (BHB), in order to estimate total circulating ketone levels. In general, BHB levels of 0.5 to 3.0 mmol/L may indicate ketosis, but this can vary somewhat from person to person. Guidelines for interpreting blood ketone testing results are typically:
- Normal (not in ketosis) – up to 0.6 mmol/L;
- “Medium” ketosis – 0.6 to 1.5 mmol/L;
- “High” or deep ketosis – 1.5 to 3.0 mmol/L; and
- Diabetic ketoacidosis – above 3.0 mmol/L.
- Negative (not in ketosis) – less than 5 mg/dL (0.5 mmol/L);
- Trace – 5 mg/dL (0.5 mmol/L);
- Small – 15 mg/dL (1.5 mmol/L);
- Moderate – 40 mg/dL (4.0 mmol/L); and
- High – above 80 mg/dL (8.0 mmol/L).