Updated: Oct 21, 2018
*** The summary below is not intended to be complete. This article is intended to be a simplified explanation of a nutrition buzz word so that you can have some information to start with when determining if it has a place in your nutrition routine. Please do your own research and consult your personal physician before making any decisions about your diet. ***
Ketosis is a metabolic process that your body turns on as a survival tactic when it runs out of glucose, resulting in ketones being present in the blood. When your body doesn't have enough carbohydrates (the preferred energy source for cellular respiration) from food intake, the body starts to burn fat instead, which it has stored for just this occasion. Essentially, to keep you going through what your body perceives as starvation, it burns the next best energy source - fat.
If you are generally healthy and eating a balanced diet, your body controls how much fat it burns so you don't normally make or use ketones. But when you cut way back, and we mean WAY BACK, on your carbohydrate intake, your body will switch to ketosis for energy. Typically, a "Keto" diet is one that is roughly 5-15% carbohydrates, 70-75% fat, and 15-25% protein. This is contrary to the traditional high - carbohydrate diets many runners follow, and notably very different from many of the high-protein diets such as Atkins or Paleo that have been popular in recent years. One common misconception is that a ketogenic diet is high in protein. This is far from the case, and a common error people make when beginning a "Keto" lifestyle. Fat is king in "Keto," and carbs and protein are minor supporting characters.
For healthy people who don't have diabetes, hypertension, and aren't pregnant or breast feeding, ketosis usually kicks in after 3 or 4 days of consuming a diet following the above ratios. While there are commercially available test strips that can identify if ketones are present in the blood, therefore signaling the ketosis process, they are generally unreliable, and the only true way to know if you are in ketosis is through a blood test. Recently, the NIH has conducted some research on the effectiveness of ketogenic diets on athletes. It's important to note that the original intent of a ketogenic diet was to treat epilepsy in children, but has made its way into the mainstream as an appealing (from a food choice perspective) way to shed pounds and improve body composition. While some studies indicate that athletic performance does not suffer while maintaining a ketogenic diet, the overall body of evidence is often conflicting.
Now, we all know that there is no "magic bullet." Ketosis is at its root a survival process, can become dangerous when ketones build up. High levels lead to dehydration, kidney stones, hypoglycemia, and anemia, as well as vitamin and mineral deficiencies. You can also experience the "Keto Flu," which includes dizziness, sleep problems, heart palpitations, bad breath, decreased athletic performance, diarrhea and muscle cramps. Whatever your current goal (weight loss, body recomposition, athletic improvement), it is imperative that you research any major change to your routine, so please make sure you consult your medical professional and do your due diligence before you jump head first into that "Keto Lifestyle."
To learn more about Ketosis, we recommend the book, Ketosis: A Beginners Guide by Linda Westwood. To learn more about low carb diets with prepared meals shipped direct to your door, check out BistroMD.