Before reading this, I highly recommend you check out my Biochemistry Primer which goes over a lot of important concepts that will make this easier to understand.
What is nutritional ketosis?
It is a state in which your body prefers to burn stored body fat for energy instead of carbohydrates. The way to achieve this is to eat a diet high in fat, moderate in protein, and very low in carbohydrates.
My primary goal is to lower my body fat percentage. After learning about nutritional ketosis, and seeing how effectively it worked for others, I wanted to see if I could benefit from it as well.
In a typical diet where carbohydrates are the primary source of energy, your body undergoes multiple peaks and troughs in blood glucose concentration. After a carbohydrate rich meal is consumed and your blood sugar spikes, insulin is rapidly released to bring it back down into the normal range. The problem is that insulin can overshoot a bit causing your blood glucose to dip a little too low. This stimulates your appetite and causes you to eat more carbohydrates, which then leads to more insulin being released, perpetuating the cycle.
You end up eating an excess amount of carbohydrates, which are then converted into extra body fat. Your body is also exposed to a large amount of insulin as it is trying to keep your blood sugar under control.
Having so much insulin around is detrimental because the presence of insulin actually inhibits your body from burning fat. This effect can actually persist for days! For example, if you eat a bagel for breakfast today, exposing yourself to insulin, your body will stop burning its stored fat for the rest of the day. This will continue on into tomorrow and probably the day after.
If my goal is to get rid of body fat, I need to do two things:
- Prevent my body from storing new fat
- Get my body to burn the fat that I already have.
As you can see, consuming carbs works against both of these things.
When you eat protein and fat, as they are absorbed into your blood stream, they cause no effect on your blood sugar. Since there isn’t a spike in blood sugar, your body doesn’t release any insulin.
Protein and fat also cause you to feel full faster and longer so you end up eating less over all. Maintaining a caloric deficit is important if your goal is to lose fat. As I wrote in my biochemistry primer:
A key point to remember is that your body is very efficient in storing energy. It has the ability to convert any excess carbohydrates, proteins, or fats that are consumed into stored body fat.
Any excess calories eaten, whether in the form of carbohydrates, proteins, or fats, can be converted to body fat if they’re not utilized to meet immediate energy demands or used to replenish supplies to maintain your body.
How does nutritional ketosis occur?
The process by which your body goes from burning carbohydrates to burning fats is called ketoadaptation. The key to becoming ketoadapted is to minimize your exposure to insulin by restricting carbohydrate intake.
An important fact to remember is that your body will do whatever it takes to keep its blood glucose concentration within its preferred range of 70-100 mg/dl. With only a very small amount of carbohydrates coming in, your body needs to work to keep its blood glucose concentration in this range. It begins by metabolizing its stores of glycogen.
Once all the glycogen is used up, it turns to gluconeogenesis. Gluconeogenesis is the process in which your body makes glucose from amino acids, lactate, and glycerol. This glucose is then released into the blood stream to maintain your blood glucose levels between 70-100 mg/dl.
In order to preserve the blood glucose that your body worked so hard to make, your body turns to another source for energy instead: ketones.
In this carbohydrate-depleted state, your body begins to convert its stored body fat into ketones. Ketones are then released into your blood stream to be used for energy. Organs such as your brain and skeletal muscle that normally run on glucose, stop using it, and start using ketones to function instead.
Your body is now optimized to burn its stored fat for energy.
How long does ketoadaptation take?
The entire process takes 2-4 weeks to complete.
When you are in nutritional ketosis, your body is converting your stored fat into ketones that are sent into your blood stream to be used for energy. The more fats you’re burning, the more blood ketones you will have.
Since I love playing with data, once I discovered that blood ketones can be measured directly and accurately, I immediately bought the test kit. After a pinprick, a drop of blood is placed on a test strip that is measured by a small machine.
A ketone measurement between 0.5 – 3.0 mmol confirms that you are in nutritional ketosis.
Here is a list of all the tools I’ve been using.
The best time is first thing in the morning while fasting. This will give you the most accurate reading.
Volek and Phinney describe a diurnal variation in ketone production, with the lowest amount in the AM. So if you’re in the zone in the morning, then you should be for the rest of the day, since that will be your lowest reading.
In my experience I’ve become distrustful of testing later in the day because of the potential effect of my meals. Food can still be absorbed 6 hours after you’ve swallowed it.
The reason you test is to know whether your body is producing ketones. You don’t want any ketones coming from something you’ve eaten to screw up your numbers and give you a false impression as to what’s going on.
So how many carbs should I eat to achieve this?
It is recommended to eat less than 50 grams of carbohydrates per day (for reference, an apple contains 17 grams and a banana contains 51 grams).
It is also important to only eat a moderate amount of protein, approximately 0.6 to 1.0 grams per pound of lean body mass.
For example, I currently weigh approximately 180 lbs. I estimate my body fat percentage to be 20%, which means that the amount of body fat I have is:
20% x 180 lbs = 36 lbs.
My lean body mass is therefore:
180 lbs – 36 lbs = 144 lbs.
So the total amount of protein I should eat is in the range of:
0.6(144) to 1.0(144), or 86 – 144 gm.
For reference, a burger patty contains 35 grams of protein, an egg contains 6 grams, and a strip of bacon contains 2 grams.
In order to function properly your body is constantly breaking down and building up proteins. It is important to consume enough protein to replenish the necessary amino acids your body requires.
However if too much protein is consumed, your body will convert excess amounts into glucose via gluconeogenesis to do what it can to replenish its glycogen stores. This in turn will stimulate the release of insulin, which blunts the burning of fat.
How much fat should I eat?
For nutritional ketosis, it is recommended that 65-80% of total calories should be from fat.
Assuming I eat 50 grams of carbs and 144 grams of protein, my caloric intake will be:
50 grams of carbs x 4 calories/gram of carbs = 200 calories
144 grams of protein x 4 calories/gram of protein = 576 calories
This comes out to a total of 776 calories, which doesn’t even come close to my basal metabolic rate of 1700 calories. This doesn’t include any extra activity I do such as digesting food, brushing my teeth, walking to my car, BJJ, surfing etc.
For me, just to meet my basic metabolic demands I need to eat an additional 924 calories from fat, which comes out to about 54% of my total calories. I can bump this percentage up to the 65-80% range simply by eating more fat, decreasing my protein intake (144 gm is at the top of the recommended range), or doing a combination of both.
Since I am fairly active, my daily estimated caloric expenditure is actually in the vicinity of 2700 calories, so as long as I’m eating less than 2700 calories, my body will be burning more fat than it’s storing.
Here is a post I wrote about why the amount of calories you eat matter.
Thank you for reading this. I hope you’ve found this to be helpful.
The primary resource I used for this was The Art and Science of Low Carbohydrate Performance