The short answer: ketosis occurs when the body burns fat for fuel as a result of insufficient carb intake.
The long answer takes a bit more explaining, starting someplace that is not ketosis or even about ketones, but in how the body creates and uses energy on the typical carb-tasic diet common in our society.
What powers you?
The body is powered by ATP (adenosine triphosphate) often called the “currency of life,” but you could think of it more like an energy fuel tank.
Carbs, fats, and proteins can all be used to produce fuel for that tank, but just like many of us, the body has a taste for simple carbs. Sort of, at least in the sense that simple carbs are broken down into a usable fuel source faster and easier than any other source. In the case of carbs, that fuel source is glucose– the preferred fuel source of the body.
Can you have too much fuel?
If your tank is nice and full, but you find all this free fuel lying about, what do you do now? You stockpile it. In this same way, when the body has more fuel available than energy demands dictate, it stores it.
Specifically, excess glucose in particular is first converted it into glycogen. Unfortunately, there’s also a limit on how much glycogen the body can accommodate. Once that storeroom is full, the body expands its storage space. It begins to produce adipose tissue—fat.
How do you empty fat stores?
As a result, the only way to get rid of fat is to use up the body’s fuel storage so that extra space isn’t necessary. The body though, it doesn’t get the concept of rotating stock. It won’t use what’s in storage if there’s plenty of new product rolling in. I mean why dig to the back when what’s up front is so easy to use? If you provide your body with ample or excess fuel, you won’t lose any weight.
This is where ketosis begins to become relevant. Ketosis is a natural backup system the body uses if carb intake is greatly reduced, for example, in times of starvation or a very low-carb diet. When the body’s carb intake is restricted dramatically, readily available glucose is also reduced. The body then has no choice but to break into its stockpile and begin breaking down fat into ketones.
Ketosis, literally “ketone condition,” is a metabolic state where the body is producing ketones for fuel. Ketones are essentially the glucose of fat, the final form after processing that ultimately creates ATP.
Put plainly, fat used, fuel made, weight lost. Awesome, right?
So, how do you get into ketosis? Well, one way is by following the Keto Diet.