The Ketogenic Diet: How and Why does it Work?

To say this diet has taken the health and fitness industry by storm is an understatement. There have been many diets that have been promoted as the best diet EVER over my fifteen years in the industry — Mediterranean and Paleo come to mind, but I don’t think any of them have had as much pervasiveness through the industry as this one.

Although its mainstream popularity has only recently taken off, the Ketogenic Diet has actually been around clinically for many years, specifically in the treatment of epilepsy, to help reduce seizures. The key to the Ketogenic Diet is to keep your carbohydrates low, very low. Your total carbohydrate intake needs to range from 5-20% while your total fat intake needs to be up around 75%. While this goes against traditional eating guidelines, the evidence suggests that this is actually really good for you, increasing fat loss and reducing inflammation in the body.

Ketosis is a normal bodily process that occurs everyday, regardless of how many carbs you eat. When you eat carbs (or even excess amounts of protein), your body breaks this down into glucose. Glucose is used to create adenosine triphosphate (ATP), which is used by the body for immediate energy.

When glucose is in excess in the body, your body removes it through two processes. One is called glycogenesis, which is when excess glucose is converted into glycogen (the storage form of glucose) and stored in the liver and muscles. The other is lipogenesis - when the liver and muscles are full with glycogen, excess glucose is converted to fat and stored in the body.

Image: An infographic on how ketosis and some of the definitions behind it

Ketosis occurs when the body has no glucose or glycogen to draw upon for energy.

When your body has no glucose or glycogen, your body goes into ketosis, using fat as an energy source rather than carbs. More specifically, in the absence of carbs, your liver breaks down fat, releasing glycerol and fatty acids.

Fatty acids are broken down further, into a ketone body called acetoacetate.

Acetoacetate is then converted into two other types of ketone bodies:

One of these is acetone. The other is known by a big name — “Beta-hydroxybutyrate”. We’ll call it BHB for short (and simplicity). BHB is a preferred source of fuel by the brain.

It is these ketones in the form of BHB that your brain and muscles use for energy.

Studies show that your brain and body actually perform 70% more efficiently using ketones for energy than glucose.

As you can see, your body still produces glucose on the Ketogenic Diet from the glycerol that is created in the initial stage of breaking fat down in the liver. Small amounts of glucose are needed in the body (to create ATP for short-term, immediate energy) but carbs are not needed to create it. In addition, about half of any excess protein is also converted into glucose. Therefore, too much protein is a bad thing. Too much protein, along with more than 20% carbohydrates, will knock you out of ketosis.

All in all, ketosis is a pretty cool thing. And you can see why the Ketogenic Diet has the health and fitness industry completely besotted. Your body burns fat, inflammation is reduced, it reduces blood glucose levels, there’s a reduction in fatty liver; and your body runs 70% more efficiently.

Final thought: Ketosis is a completely normal process that occurs everyday, even if you eat carbs. Think about when you’re sleeping. However, you can slip out of ketosis quite easily by consuming fruit or other carbohydrates such as bread, meaning you’ll start using glucose and glycogen again for energy instead of those ketone bodies such as BHB. Lollies and cakes are certainly out.

Eventually, your body will expel less ketone bodies in the form of acetone. If you’re measuring your levels, you can be forgiven for thinking your body is slowing down with the fat burning process. This is not the case. Your brain is burning BHB as an energy source and your body wants to give your brain as much efficient energy as possible.

If you do decide to start the Ketogenic Diet, you should stick with it for the long term. As with anything, short-term compliance doesn’t work. It’s a lifestyle change. You can start eating fruit and simple carbohydrates again but you should transition gradually. If your goal is weight loss, transitioning too quickly off the Ketogenic Diet can result in putting all your weight back on, and then some. With the support of a professional, create a goal with a plan that will get you to your target. Then you can follow the Ketogenic Diet effectively and make long-lasting, sustainable change.

Question: Have you tried the Ketogenic Diet? What was your experience? If not, what thoughts has this article left you with? Leave your questions and comments in the discussion section below.