A ketogenic diet switches your body from carbohydrate burning to fat burning. The trick is to stay in ketosis while enjoying wholesome nutrition. First we need to understand how our body burns fuel. Carbs are the body’s main source of fuel. Carbohydrates (except fiber) are metabolized into monosaccharides of glucose, fructose, and galactose.
A little on fructose, a very misunderstood sugar. Fruit and honey have a blend of glucose and fructose. Sucrose (table sugar) is a 50/50 blend of glucose and fructose. High-fructose corn syrup is formed through converting 55% (typically) of the corn’s glucose into fructose giving it a 55/45 blend. It has a higher fructose than glucose concentration, hence why it’s called “high-fructose.”
Galactose is a metabolite of lactose, the sugar in milk. Neither fructose nor galactose cause an insulin response by the body. Glucose, on the other hand, does. Insulin triggers the liver to release VLDLs, the lipoproteins that carry cholesterol and triglycerides, depositing triglycerides into fat cells. This is why that piece of cake goes straight to your hips, or belly! It also causes a rise in LDLs (bad cholesterol) leading to atherosclerosis.
Both fructose and galactose are used to produce glucose. The body uses glucose to create energy. Glucose is converted to pyruvate. Pyruvate is converted to oxaloacetate and acetyl CoA; both of which are needed to run the Kreb’s cycle. So, what happens when we fast or eat a low carbohydrate diet, such as a ketogenic diet? The first thing your body does, after it uses up its glycogen (storage form of glucose), is use amino acids to make glucose in order to produce pyruvate. However, after a week or so you will switch over to using primarily ketones and need less glucose.
When you consume protein your body breaks it down into its component amino acids and is stored in an amino acid pool. These amino acids are used as building blocks to create protein, cholesterol, glucose, ketone bodies; and, are stored as fatty acids (fat) when your body has exhausted its uses. Alanine and glutamine are the most utilized amino acids to produce glucose by the liver. If you are not eating enough protein your body will break down its own muscle for survival. A normal healthy adult should consume 0.8 g protein/kg body weight. In order to build muscle, you need to do weight bearing exercise and can increase your protein intake. To ensure an adequate amino acid pool available to build and repair muscle, endurance athletes need to consume 1.2 – 2 g protein/kg body weight while strength and power athletes need to consume 1.4 – 2 g protein/kg body weight. Exceeding 2 g protein/kg body weight could put too high a nitrogen load on the kidneys. Also remember, if your body is not utilizing the protein, then you will store it as fat.
Next, your body will start using its fat stores. Yay!! When this happens it also triggers amino acid ketone body formation, primarily with leucine and lysine. The byproduct of metabolizing fat is ketone bodies. Basically fatty acid oxidation overwhelms the Krebs cycle and it starts storing energy as ketones. Ketones can be converted into acetyl CoA to fuel the Krebs cycle. When you are producing ketones your body is in a state of ketosis.
The only caution to this situation is a type 1 diabetic not taking their insulin and on a ketogenic diet. They are not able to utilize glucose. So their body goes into overdrive breaking down fat and producing an overabundance of ketones. Too many ketones cause ketoacidosis, making the blood acidic which would lead to coma and death if not treated. A normal healthy individual with functioning hormones will maintain glucose and ketone body formation within healthy levels. Excess ketones are excreted in the urine.
Ketosis is a natural state. We go into ketosis at night. It is a survival mechanism. We store fat in times of feasting & use the fat in times of fasting. This is how we survived throughout history. Eating a ketogenic diet is low carb (less than 50 g of carbs per day). You can buy ketone strips to see if you are in ketosis. If not, you may want to lower your carb consumption. As with everything, if you eat too much protein and fat you will gain weight. It’s not a license to eat as much of anything else you want as long as it’s low carb. 🙂