what is keto diet

A Balanced Approach to Keto Series: What is the Ketogenic Diet?


What’s the first thing that comes to your mind when you see that word?

With all of the history and social-emotional stigma about dietary fat, it does seem surprising that a diet that reaches upward of 75% of your caloric intake from fat has become so popular.

Maybe you’ve heard about this diet or had someone recommend it to you.  Maybe you’ve jumped on the “Keto” bandwagon or maybe you’ve just started adding butter to your coffee.  In this series, “A Balanced Approach to Keto”, we’re going to take a closer look at the Ketogenic Diet from a holistic and “balanced” perspective for the body.  We’ll dive into why it may be good for some people and not for others, and we’ll provide some guidance to help you understand if it might be right for you.

In order to understand about the Ketogenic Diet, you need to first understand a little about the way the body manages and uses glucose so we’re going to have to dig into the biologic complexities of the human body.

The human body has two primary sources of energy:

  1. Glucose which comes from carbohydrate, and
  2. Ketones which are made from fat.

(Actually, alcohol is #1 so when that’s present your body will burn through it first since it has no other place to put it.  Keep this in mind if you’re having alcohol with a meal!)

Fundamentals of Glucose for Energy

When present, the body will normally use glucose for the fuel supply first; but it doesn’t need very much – only about 4 grams (or 1 teaspoon) is needed for a normal blood sugar level.  About 60% of this is needed to support the brain; the rest supports the remainder of the body’s energy needs in a sedentary state.  It’s important that the blood not be too high nor too low in glucose and so it uses a hormone, insulin, to pull excess glucose quickly out of the blood and into the cells to be used for energy in the mitochondria. (The mitochondria are the little furnaces inside of your cells that turn food into energy.) Anything left over from the bloodstream that isn’t needed for the cells is stored.

Glucose Storage

The first stop on the path to storage is the short-term storage reservoirs in the liver and muscles. Through a process called “glycation”, the body binds the glucose molecules to a protein or lipid (fat) molecule, creating a new molecule called glycogen.  The body has capacity to store about 1,000-2,000 calories of glucose as glycogen in your liver and muscles (~100g and ~400g, respectively).  This is used to help facilitate your body’s immediate energy needs.  Glycogen stays in reserve until it’s needed, such as when you exercise or need to power the fight or flight stress response.

Glycation storage is finite, however and if it’s not used then it doesn’t take on any more glucose.  Whatever glucose is left over from the first stop at glycation is moved to long-term storage in the fat cells.  The glucose molecule is converted into a triglyceride (3 fat molecules bound by a sugar called glycerol) and stored in body fat – usually around your mid-section. This is there to support your body in case of a shortage of food.

How Fat Becomes Energy Too

What happens when we replace the glucose (carbohydrate) energy source with ketones from fat?

Ketosis is the process that your body goes through to convert fat sources (from food or from storage in the body) into energy. Remember the excess glucose that got stored as a triglyceride in fat cells?  Through a process called “lipolysis” the triglyceride is pulled out of the fat cell (which is how this relates to weight loss)

  • An enzyme called Hormone Sensitive Lipase (HSL) breaks the triglyceride apart.
  • The three fat molecules flow through the bloodstream.
  • The liver picks up on this and switches on a process called beta-oxidation that breaks down the fat molecules into usable energy.

If you’re wondering about the glycerol molecule – that gets converted back to glucose by the liver through a process called gluconeogenesis.

The Application of the Keto Diet

The ketogenic diet is based on high amounts of fat, moderate amounts of protein, and low amounts of carbohydrates.  It’s really the low carbohydrate ratio that drives the conversion of the body’s metabolism to use fat (ketone bodies) for energy.  This means the blood doesn’t contain excess glucose, so large amounts of insulin are not needed for storage.  Rather, the ketones enter the cells and are taken in by the mitochondria to be used for energy.

So why raise fat intake and not protein?

Simply put – our bodies are setup better for fat than protein as an energy source.  Proteins contain nitrogen.  The body has to go through great effort to remove the nitrogen to get to a useable source of energy – a process called “deamination”. The nitrogen ends up as an ammonia byproduct that has to be filtered out by the kidneys.  Fat also provides more energy (calories) per gram. There are 9 calories per gram of fat and only 4 per gram of protein and carbohydrate.  (An important distinction from days before we had food stops on every corner where you can get a meal with very little calorie expenditure.) Remember a calorie is defined as a “unit of energy.”

By now you should be able to see how this diet has been successfully applied for weight loss. It’s also been useful in balancing blood sugar and reducing systemic inflammation.  Many other health conditions are still being studied through a Ketogenic Diet for short and long-term benefit.

Like all diets, individuals will react, well, individually.  Some people thrive on a low-carb diet and some do not, and some do, but just not right now.  Why are people so different?

Continue to follow our “A Balanced Approach to Keto” series to learn how to determine whether a Ketogenic Diet may be right for you.


Disclaimer: Nutrition therapy is not intended as a diagnosis, treatment, prescription, or cure for any disease, or as a substitute for medical care. Jen Marshall and Stacy St Germain are not licensed medical providers. Nutrition plans are not intended as a substitution for traditional medical care, nor should be interpreted as medical advice, but instead is an adjunctive and supportive therapy.