First off, it's good to start by learning how your body normally works with energy sources. Your body either burns sugars, it burns fats, it burns proteins, or it burns alcohols. These are the four types of fuel the human body can process.
The human body was developed over millions of years to burn fats and proteins for energy and get nutrients from healthy vegetables. A number of cultures, like the Inuit, still thrive with this natural eating system.
However, in the past century we began flooding our bodies with sugars - soda, processed foods, white rice, white bread, and artificial additives. The amount of sugar hitting our bodies was incredible. Diabetes and obesity skyrocketed.The body first looks around for sugars, because it figures it should burn those first (which is why people overeating sugar tend not to lose fatty weight). When the body decides it should move on to burning fats, the liver starts pulling fatty acids either out of what you've eaten or out of your fat stores. This normal fat-burning state of the body is called ketogenesis. It's what your body is supposed to do once it's done with sugars - convert incoming and stored fats into ketone bodies for energy. The end state has ketone bodies in the blood, which is called ketosis.
One of your body's key missions is to keep the brain well supplied with nutrients and fuel. It tries to get rid of sugars first in this quest - but when there aren't sugars, it turns to fats as a fine alternative. The brain needs about 100g of glucose or its equivalent in fatty acids and ketone bodies each day for its normal operations. In the liver, fatty acids are broken up into ketone bodies via ketogenesis. Now the brain is nicely supplied with exactly what it needs - and you are losing weight.
A tiny technical note. The liver creates acetone, acetoacetic acid, and beta-hydroxybutyric acid - and the third of those is NOT technically a ketone. That's why this group should be called "ketone bodies" and not just "ketones". Many people do call these "ketones" for short, so if you see ketones mentioned in articles, that's why.
In any case, these ketone bodies circulate in your blood and are used by cells including your brain. Ketone bodies cannot be turned back into fats, so any extra ketone bodies in your system are just peed out. You can buy Ketone Strips at just about any drugstore that detect those ketone bodies. Those can prove that you are in ketosis and indicate just how much fat is being flushed from your body.
Some people confuse ketosis with ketoacidosis. Ketoacidosis is actually a high sugar condition that is an insulin issue with Type-1 diabetics. It can also happen with binging alcoholics who have damaged their liver. So neither case relates to healthy low carb dieting.
So in short, ketosis is a normal, healthy state for your body to be in when it's in a low-sugar environment. Remaining low sugar is the way many cultures work on a daily basis. Ketosis and ketogenesis are simply related to how a body manages energy for the brain when the body isn't being fed a high-sugar diet.
Ketosis is not unhealthy, and it is not dangerous! It simply means your body is burning fats for energy.
Using Ketone Strips and KetoStix
Lisa Shea's Library of Low Carb Books
