The three main macronutrients that are related to the ketogenic diet are fat, protein, and carbohydrates. These three nutrients have different effects on ketosis from digestion and have consequential effects on blood glucose and hormones.
- The fats are 90% ketogenic Y 10% anti-ketogenic, due to the small amounts of glucose that are released when they are converted into triglycerides.
- Proteins are typically rated as 46% ketogenic Y 58% anti-ketogenic since insulin levels increase since a little more than half of the protein consumed will be converted into glucose.
- Carbohydrates are clearly 100% anti-ketogenic since they raise both glucose and insulin.
Protein and carbohydrates are going to impact our bodies away from transitioning into ketosis, but the most important thing to understand is how these three nutrients are being used for energy. This happens through our metabolic pathway after we consume the nutrients.
Well, you must be wondering what the heck is the metabolic pathway. In essence, it is the way our bodies handle the breakdown and absorption of fats, proteins, and carbohydrates; and how you use these depending on the “current state” of our body.
There are three different states in which we can find ourselves:
- Fed – Immediately after a full meal.
- Fast – when you have not eaten between 2 and 8 hours.
- Starvation – when you have not eaten in more than 48 hours
In the fed state, the main nutrients are broken down in various metabolic pathways:
- Fats go directly to the liver to be converted into fatty acids and glycerol. These are then sent around the body to repair cells and generate different chemicals/tissues in the body. Excess fats are stored as triglycerides in fat cells.
- Proteins are processed as amino acids through transamination and sent to the body to create neurotransmitters, nonessential amino acids, and other protein-based compounds in our body. If we have extra amino acids, these circulate and repair tissues or are stored as glucose.
- Carbohydrates break down into glucose which is used immediately as energy. The spike in glucose levels will trigger the release of insulin, which will then help store glucose either as glycogen or fat in our cells.
The fasting state happens when our blood glucose is at a low level, which also means that our insulin levels are low. With the drop in blood glucose, another hormone called glucagon is released to supplement energy processing from stores.
In the fasting state, our nutrients are used by different processes, but they are all metabolized in the same way. They are all split into acetyl CoA, which is very important for creating ATP (an energetic molecule) in the Kreb Cycle.
- Glycogen from the liver is released, and blood glucose levels rise. As a result, this glucose is used primarily by the brain and red blood cells.
- Free fatty acids are released from fat cells which are in the form of triglycerides. These are our primary source of energy for the liver and muscles while we sleep. The liver will also form ketones from these, and we can use them as an energy source if necessary. More triglycerides are digested and released if we stay in a fasted state for longer.
State of Starvation
Once we have been fasting for more than 48 hours, we transition to a state of starvation. The glycogen in our muscles and in the liver will run out. The liver will begin to break down lactate to generate more glucose and give energy to our red blood cells.
- The liver begins to produce ketones that enter the bloodstream, and our brain and muscles begin to use them for energy through oxidation.
How is this all related to the ketogenic diet? With the lack of glucose in our systems, our body begins to mimic a state of starvation. The liver creates more ketones to use for energy since there is less glucose available – so we use more of our stored fat for energy.
Protein is vitally important on the ketogenic diet, but it is also a tricky nutrient. If we don’t eat enough protein, we lose muscle mass. You may be thinking “well, then I’m going to eat all the meat I can and thus saturate myself.” Boy, would that be yummy, but massive amounts of protein would raise our blood glucose levels.
As we saw earlier, protein is 46% ketogenic and 56% anti-ketogenic, meaning that eating a lot of this would get us out of ketosis. We must stay within very narrow margins in our protein intake; enough not to lose muscle mass, but not so much that it takes us out of ketosis.
This narrow range is very difficult to determine as it differs from person to person. Some people have reported problems staying in ketosis while eating excess protein in a single day, or eating too much protein in one sitting. Others consume 2.45g of protein per kilogram of weight and have no problem transitioning or staying in ketosis.
This may also depend on the amount of exercise you do, as depleting glycogen will allow you to use up your carbohydrates faster. This being the case, the amount of protein suggested to consume depends on your lean muscle mass and your level of activity.
- Sedentary: 1.6gr of protein per kilo of lean mass in your body.
- Slightly active: 1.6 – 2gr of protein per kilo of lean mass in your body.
- Highly active: 2 – 2.5gr of protein per kilo of lean mass in your body.
Despite the ketogenic diet being known for high amounts of fat consumed, dietary fats have minimal effect on ketosis. Ultimately, your fat intake will determine how much of your body fat is used for energy.
Since fats are 90% ketogenic and 10% anti-ketogenic, we can get away with consuming high amounts. Yes, glycerol from triglycerides produces glucose, but think about it in relation to the number of grams you eat. If you eat, say, 160gr of fat in 1 day – that’s just 16g glucose.
Since fats are mainly consumed throughout the day and not in one sitting, your body is going to be using glucose without you even realizing it is there. The only time we should avoid consuming fat consistently is after exercising. Fats slow down the digestion process and will encourage the absorption of the protein you eat after exercise, so it is not recommended.
With this being the most restricted nutrient on the ketogenic diet, carbohydrates are the ones that have the greatest effect on ketosis. The general rule is not to consume more than 30gr of carbohydrates in one day at the DCE.
By processing carbohydrates, they are converted almost gram for gram into glucose when they enter the bloodstream. Here, glucose has a number of things to do. Whether it is immediately burned as an energy source, stored as glycogen in the muscles or liver; or if carbohydrates are consumed in excess, it will be stored in the fat cells.