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The Ketogenic Diet & You: What Is Really Going On?

Published on: April 08, 2019

The Ketogenic Diet & You: What Is Really Going On?

The ketogenic diet has become more well-known recently, with good reason. It is the one dietary approach that creates a very novel physiologic effect. By restricting carbohydrate (sugar) intake, a state of nutritional ketosis is created. Let’s take a closer look at what is actually happening as someone begins and maintains a ketogenic diet.

Starting the Ketogenic Diet: Macronutrient Balance and Blood Testing

The first step is to adjust macronutrient intake (carbohydrates, fat and protein), aiming for the classic percentages of calories from each category being roughly 75% fat, 15% protein and 10% carbohydrate. What this does is vastly diminish the supply of carbohydrates for fuel. Carbohydrates are broken down in the digestive tract and released into the blood stream primarily as glucose, the main form of sugar (and energy) in our body.

You may also consider doing blood work before starting the ketogenic diet. Paying special attention to blood glucose and insulin levels can help monitor your progress on this diet:


Blood glucose levels

You may have had your blood sugar checked before. Diabetics check this value frequently, to help monitor and improve these levels. Normal levels are considered less than 100 mg/dL (5.6 mmol/L) when fasting. If the fasting glucose is 100 to 125 mg/dL (5.6 to 6.9 mmol/L), we call this prediabetes. If the fasting glucose is 126 mg/dL (7 mmol/L) or greater on two occasions, we call this diabetes.

As a functional medicine doctor, I also check additional markers, to get a full assessment of glucose balance. These include Hemoglobin A1C (which assesses a three-month glucose average) and insulin. A Hemoglobin A1C level below 5.7 percent is considered normal, between 5.7 and 6.4 percent indicates prediabetes and over 6.5 percent is considered Type 2 diabetes.

Insulin levels

Insulin levels less than 25 mIU/L (174 pmol/L) are considered normal. But in a nation where normal does not exactly equal healthy, in my view the optimal range for A1C should be closer to 5.0 percent, and under 8 mIU/L for fasting insulin. The higher the glucose, A1C and insulin go, the greater the communication problems relating to blood sugar balance are, and thus risk for chronic diseases such as diabetes and heart disease.

Insulin is a very important hormone. It directs glucose into cells, so they may use it for fuel. In our modern society, with its always-plentiful, high-carbohydrate food supply, insulin balance is particularly challenged.

After a carbohydrate-containing meal blood sugar increases, correlating with the amount of carbohydrates in that meal. This then causes a mirror-image increase in insulin, so that the glucose can be escorted from the blood stream into cells and be used for fuel.

Metabolic Dysregulation and How the Keto Diet Can Help

A major problem of the typical Standard American Diet (read: pizza, burgers, sandwiches, cereal in ready supply and limitless quantities) is that it contains far more fuel (glucose) than we need and can actually use.

For a lot of people, this causes a greater and greater increase of glucose over time, as these systems become gradually become overwhelmed and inefficient. More insulin is then produced in an attempt to correct the situation. Insulin Resistance, a common metabolic condition, is a snowball effect of glucose and insulin, set off by our modern food supply. Weight gain is a by-product of this glucose-insulin dysregulation.

The ketogenic diet is used to stop this vicious cycle, by cutting out a major player: glucose. But we need some form of fuel to survive, of course. Unless someone is following the ketogenic diet or fasting, they will be using carbohydrates (thus glucose) as their fuel. The basic tenet of the ketogenic diet is that it is providing you the fuel to survive (and thrive, hopefully) without relying on sugar for fuel. This is notable, as this switch completely changes metabolism at its core.

Before, glucose was being burned for fuel. Now, fat is. This produces several important changes.

Initially when starting a ketogenic diet, the blood glucose will decline, as the body uses up its store in the blood stream and liver.

After continuing the ketogenic diet for 12-48 hours (depending on your activity level, and unique response to glucose and insulin), nutritional ketosis begins. Stemming from a need to find a new energy source (since the glucose is now in short supply), the body begins to fuel itself by breaking down fatty acid molecules in fat cells. This process is called Fatty Acid Beta-Oxidation. Even the most thin person has a large store to tap into. While in ketosis, the fatty acid molecules are being broken down to provide the much needed energy. Available any time, in almost limitless stores.

As the glucose falls, so does the need for insulin, since it’s the hormone that tells glucose where it should go. The now-unnecessary insulin is broken down by the kidneys, causing a shift in electrolyte balance in the kidneys to excrete (get rid of) that insulin.

At the same time, the fatty acid molecules are being broken down, which creates ketones. These ketones are called beta-hydroxybutyrate (BHB), acetoacetate and acetone.

Nutritional Ketosis: How to Check and What to Expect

When someone is checking whether they are in nutritional ketosis or not, they are checking whether their body is producing ketones. Urine ketone strips and finger-stick devices are checking for the presence of BHB. Breath ketone analyzers are checking for acetone. If the urine ketone strip is positive, this indicates presence of ketones. Those ketones would have to come from either ketogenic production in one’s body (showing they are in ketosis), or a supplement (if recently taken).

The insulin flushing, along with the natural metabolism of the ketones is what can create an electrolyte imbalance in the kidneys. Changes in sodium, potassium and magnesium can occur. These shifts are why electrolyte supplementation is often used, especially in the early transition period (first 1-3 weeks). Another important piece is to maintain hydration, as water is used up at an increased rate with these processes.


This flushing of electrolytes, insulin and water is what is responsible for the dramatic weight loss often seen on the scale in the first week of the ketogenic diet. It is not unusual for someone to see a 5-10 pound weight loss, with just a little bit of this being actual fat burned. After this initial phase, the more sustained 1-2 pounds every 1-2 weeks typically seen is attributed to actual fat lost.

In the first week, if you are checking both your glucose and ketones, you would expect to see a drop in the glucose with a corresponding rise in ketone production. This is not a dangerous drop. For example, you may see a fasting glucose of 95 mg/dL fall to 75. This is a good thing! It is showing improved insulin sensitivity, a reversal of the all-too-common Insulin Resistance process.

Timing of Ketosis and Keto Adaptation on a Ketogenic Diet

Ketones typically come onto the scene after 3-7 days of starting a ketogenic diet. The presence of ketones on monitoring and burning of fat for fuel will continue as long as the ketogenic diet is maintained. The higher the number (within the healthy physiologic range of nutritional ketosis), the more ketones are being produced, which reflects the amount of fatty acid molecules being burned.

So, although I don’t recommend a specific target goals for ketone production, if someone is following the ketogenic diet specifically for weight loss, I would expect that to happen more readily if their ketones were 3.0 mmol/L as opposed to 0.3 mmol/L.

Another common effect starting early in the ketogenic adaptation is improved satiety. This means you feel appropriately full after meals and can go for more extended periods between meals without feeling “hangry.” This is because with the healthy drop in insulin, additional fat-derived hormones called leptin and adiponectin change.

If you feel constantly-hungry, not satisfied after meals, and can’t go more than 2-3 hours between meals without feeling blood sugar crashes, chances are your leptin is too high and your adiponectin is too low. Particularly if you seem to under-eat and gain weight no matter what. By transitioning into ketosis, the leptin comes down, and the adiponectin increases, which is the exact direction you want for feeling satisfied with your meals and seeing weight loss.

Beyond the early phase, there are many more additional positive markers we can see over the weeks and months to come.

The liberation and breakdown of these fatty acid molecules for fuel is why the ketogenic diet is used for weight loss. While in ketosis you are now able to make those fat cells work for you, instead of against you. They are a great source of energy, and will diminish as their fat supply is used up. The fat cells don’t disappear, they just shrink as their stores are burned for fuel.

Cardiovascular Health and the Ketogenic Diet

For some with elevated blood pressure, we see that improve, due to the now steady low level of insulin (low carbohydrate means low glucose means low insulin). Insulin Resistance, a metabolic condition creating elevated insulin levels, is a major factor behind high blood pressure for many.

There are also quite a bit of changes we can see on a cholesterol panel. I caution checking these too early in the process, because for some there is a transient increase in the fat-shuttling particles as your body is getting used to the ketogenic diet. These panels are typically checked annually, and I suggest no sooner than 6 months into the ketogenic diet.

We often see improvements in those markers associated with heart health, and a decline in those markers associated with heart disease risk (higher HDL and LDL particle size with lower triglycerides). These changes are attributed to improved handling of dietary fats when keto-adapted, as well as improved insulin sensitivity, which is a natural by-product of the ketogenic diet.

Hormonal Health and the Ketogenic Diet

Hormones such as testosterone and cortisol also show improvements with a ketogenic diet. For women with a quieting down of the testosterone excess, which is at the core of many symptoms seen such as hair growth, acne and irregularity of menstrual cycles and fertility. This does not mean that men should fear lowering of testosterone on the ketogenic diet. Interestingly, it is shown to improve levels in men who exercise (and who should be exercising? Everyone!).

Cortisol, in appropriate levels helps us get up in the morning and stay alert. But in high-stress environments, which are so common in our society, cortisol can become excessively stimulated, and is called the stress hormone for this reason. This excess leads to more and more fight-or-flight stress responses.

Another major contributor to out of control cortisol is insulin spiking. High carbohydrate meals cause a roller coaster response of insulin production. High carbohydrate causing high insulin causing high cortisol. It’s recipe for disaster in the form of feeling stressed and depleted. Being in ketosis allows for the insulin to naturally fall to healthy levels and prevents the insulin-cortisol spiking associated with stress.

So, by following the ketogenic diet everything sounds pretty great, right? In general yes, but there are a few physiologic pitfalls to watch out for.


Other Caveats of the Ketogenic Diet

In addition to the electrolyte imbalances mentioned previously, there are a few additional considerations to be aware of.

Depending on your level of activity and exercise, you may feel quite a change with using fat instead of sugar for fuel. Sugar is burned into energy very quickly. Fat is a more sustained gradual burn. Individualization of dietary intake is a must if you are a competitive athlete or participate in high-power explosive energy activities such as Crossfit or certain martial arts. It is completely possible to successfully enter and maintain ketosis, and see athletic improvements, but the approach just needs to be personalized.

Another major factor is that if you are on medication, you should be working with your doctor particularly close during the ketogenic transition.

Because ketosis works so extensively throughout the body, nearly any type of medication could be affected. Diabetic, blood pressure and cholesterol medications will of course need to be carefully monitored (because you could end up overmedicated, by needing less on the ketogenic diet), but also medications addressing anxiety, depression, kidney function and gout are others I often see needing to be watched closely. Even anti-inflammatory medications may need to be reduced or eliminated. For optimal effect and safety, your doctor should be familiar with ketogenic physiology and its effect on any medications you are taking.

In addition to storing fat molecules, fat cells are also relatively safe storage sites for excess hormones and potentially harmful compounds from our environment (such as plastic compounds, heavy metals and other contaminants). Especially if you have a known exposure, particular guidance should be paid to helping your body safely get rid of these compounds as they are being released. Burning excess fat is great, but liberation of some of these other compounds may be problematic. At a minimum, adequate fiber intake helps escort out these unwanted toxins.

There are so many great reasons to use the ketogenic diet to improve your health. With education, preparation, planning and guidance you can set yourself up for best keto success.

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