How Ketosis, Ketones, and a Ketogenic Diet Work
For ages, we've been taught that we need carbohydrates and glucose as the primary source of energy for our body. We've been told that eating a diet rich in healthy whole grains was the key to health and wellness. However, with each passing day, there is an increasing amount of research proving that there is an alternative fuel source.
A fuel source that can actually be more efficient, help us burn fat for fuel, and increase our overall health: ketones. This article provides a beginner’s guide to ketones, ketosis, and the ketogenic diet.
What are Ketones?
Ketones are water-soluble molecules produced in the liver when the body breaks down fat for energy through a process known as ketogenesis. This happens when blood glucose levels drop as a result of fasting, eating a low carb diet, or strenuous exercise.
As it turns out, ketones may actually be the preferred source of fuel for our brains. This is because they can provide more cellular energy per unit of oxygen compared to glucose.
There are three types of ketone bodies, or ketones, that the liver produces from breaking down fat:
- Acetoacetic acid
- Beta-hydroxybutyrate or BHB
Beta-hydroxybutyrate (BHB) is the most abundant form of ketone found in the body followed by acetoectic acid and then acetone. BHB is able to pass through membranes easily and thus be transported into the brain for use as energy. Ketones are able to be used for fuel by all organs and tissue containing mitochondria.
Mitochondria are the factories within our cells that produce energy. Because ketones are more efficient at producing energy and they require less oxygen, they may be the preferred source of fuel. They can also help improve mental and physical performance while helping to protect against other neurological diseases that stem from low energy production in the brain.
Not only can BHB be a more efficient source of fuel for the body, but a recent study has suggested that it can even lead to the increased production of mitochondria. This means more energy factories!
What is Ketosis?
Essentially, ketosis is the natural metabolic state your body goes into when it is breaking down fat for energy. Ketosis can also be described as the state of having elevated ketone levels, typically above 0.5 millimole per liter (mmol/L). Excess ketones are disposed of by your body in urine. As the body gets more efficient at using ketones for fuel, it will typically dispose of less in the urine because it is using the ketones for energy.
True story: most of us periodically enter ketosis or keto without even realizing it! Your body naturally produces ketones while fasting. So, if you had an early dinner and didn't eat again until lunchtime the next day, you'd likely have some amount of ketones in your blood.
During a fast, our bodies naturally produce ketones. However, most people do not stay in ketosis for long because we continue to supply our bodies with more carbohydrates. Because of the carbohydrates we ingest, our bodies will use or metabolize the glucose from these carbs instead of metabolizing fat. If there are elevated levels of glucose available in the blood, then the body will use glucose for energy instead of fat.
Using Ketones for Fuel
So, how does ketosis actually work and how does our body use these ketones for fuel? Well, first let's start with how our bodies use carbohydrates for fuel since we're likely more familiar with this process. Then, we'll compare this process to ketosis.
Our body naturally breaks down protein, fat, and carbs into energy through different metabolic and chemical processes. To keep it simple, when you eat carbohydrates your body converts these carbs into glucose in the stomach and small intestine. The pancreas also releases insulin which triggers your body to store the fat and use the glucose as energy. The glucose is then transported throughout your body in your blood to be further broken down and used as energy.
In contrast, when you restrict your carbohydrate intake, by eating a low carb diet or fasting, your insulin levels are lowered, fatty acids are released, and ketogenesis kicks in. You may remember from above; ketogenesis is the process by which fat is broken down into ketones by the liver. But let's talk a bit more about this process.
A Boost of Energy
When your body breaks down fat, it releases fatty acid molecules and glycerol (more on this later). Some of the fatty acid molecules are then broken down and converted into ketones, Once the body is in this metabolic state, and ketone levels are at or above 0.5mmol/L, our body is in ketosis! When in ketosis, ketones are transported by your blood throughout the body to be further broken down by mitochondria and used for energy.
A Change in Insulin Levels
You'll notice one significant difference here between your body using carbohydrates vs. fat for fuel. Insulin levels. Insulin appears to be the hormone that regulates fatty acid oxidation. Or said simply, insulin regulates whether or not fat is stored in your body or released for energy. This is why restricting your carbohydrate intake is so important to ushering in and maintaining ketosis.
The key to ketosis is that when there isn't enough insulin and glucose available in the blood to provide the body with energy, the body will turn to using fat as its fuel source and burn this fat for ketones. Fat in our body is essentially stored energy. The ketogenic diet helps our bodies unlock this stored energy and use it for fuel!
But wait, you might have heard that our bodies need glucose to function and that eating a keto diet is starving our bodies of the necessary nutrients and glucose it needs. Well, that's partly correct. Our bodies do need glucose in small amounts to maintain proper health and for the normal function of certain parts of our body, like red blood cells. This is why we don't completely eliminate carbohydrates on a ketogenic diet.
What is Gluconeogenesis?
As well, remember that glycerol mentioned earlier? Well guess what, this also provides the body with a source of glucose through a process known as gluconeogenesis. Gluconeogenesis is a metabolic pathway (or series of chemical processes) that creates glucose from non-carbohydrate sources such as amino acids from protein, lactate from our muscles, and glycerol from fat. Whoa! That was a mouthful, I know.
But wait, won't we get kicked out of ketosis then if we eat too much protein or fat. The short answer, No. So don't freak out and worry about eating too much protein. Gluconeogenesis occurs as your body needs glucose. So, your body won't go on a crazy spree creating too much glucose from protein or fat. In fact, I would venture to say that most people I talk to are getting too little protein on a keto diet and eating too much fat. If your goal is weight loss, you likely already have plenty of fat stores in your body so eating fat is important but you still need a healthy amount of protein which will help keep you full longer and will provide your body with essential micronutrients it needs.
Bottom line, our bodies can get glucose from fat and protein and don't need carbs, but we still want some carbs because this allows our body to use the protein and fat for other purposes. Hopefully, that helps clear up the myth that keto is bad for you or you are starving your body on a ketogenic diet.
In fact, some people have never eaten such a nutritious diet in their lives until they embark on a keto diet. So, let's talk more about the keto diet and how it helps us achieve ketosis.
What is the Ketogenic Diet?
At its most basic, a ketogenic diet is a low carb high fat (LCHF) diet that helps our body achieve and maintain ketosis. Thisis done by eating a specific level of fat, protein, and carbs (or macronutrients) each day. Note, we are targeting a percentage of total calories eaten per day from each macro, not a total amount of grams. Remember, fat has nine calories per gram while protein and carbohydrates each have four calories per gram.
While every individual is different and macro needs will vary based on body weight, level of keto-adaptation, exercise and other factors, the below macros are a good place to start but should be optimized for your individual goals.
No matter what your goals are, it's crucial to craft a diet that is nutritious and sustainable. Additionally, it's important to drink plenty of water and make sure you get a good number of electrolytes as your body will excrete more water as your insulin levels drop.
Keto Diet for Weight Loss
A ketogenic diet is good for weight loss because the decrease in the amount of carbohydrates you consume each day will force your body to burn the fat you have for energy because your body is lacking the extra carbs.
A low-carb diet is good for weight loss and improving and preserving muscle mass. It is also good at helping you experience far fewer cravings throughout the day, achieving a lower caloric intake, allows you to practice self-control, and urges you to participate in more physical activity (due to all the extra energy you will find you have).
However, a keto diet is just one tool to use to reach your weight loss goal, but you still need to adjust, track, and find the right balance in your life.
Keto Macros: (% of calories)
- Fat: 70%
- Protein: 25%
- Carbs: 5%
So, what does this look like for a typical 2000 calorie diet?
- Fat: 155g or 1400 calories
- Protein: 125g or 500 calories (notice how much protein this is!)
- Carbs: 25g or 100 calories
It's important to stress here that, as with any diet, we need to not only focus on our macronutrients but also ensure our body gets the micronutrients it needs. The best way to do this is to eat whole and unprocessed foods.
It's important for us to focus on the quality of the food we eat just as much as the quantity of food we eat. This also helps ensure we are eating a diet that is sustainable and hopefully delicious! Here's a sample list of what to eat on a keto diet. Check out our full keto shopping list here.
What to Eat on a Keto Diet:
- Coconut Oil
- Olive Oil
- Fish Oil
- Chicken Thighs
- Eggs & Bacon
- Pork, Sausage, Pork Rinds
- Grass Fed Beef
- Broccoli Rabe or Broccoli
- Dark Leafy Greens: Spinach, Arugula, Lettuce, Kale, Collard Greens, Bok Choy
- Brussel Sprouts
- Low Carb Nuts: Macadamia Nuts, Almonds, Brazil Nuts
- Cheese: Feta, Blue, Cheddar, Parmesan
- Caesar Dressing, Ranch Dressing, Olive Oil with Balsamic
- Low Carb Fruit: Blackberry, Raspberry, Starfruit, Melon, Coconut Meat, Lemon
What NOT to Eat on a Keto Diet
Since the keto diet has you on a low-carbohydrate diet, you should be aware of what foods and drink you shouldn’t be consuming, now that you have a pretty lengthy list of what you can have while on a keto diet.
The following are a few things you should avoid:
- High Carb Fruit like bananas, oranges, apples, and grapes
- Cooked Pasta
- Cooked Rice
- Chocolate Bars (unless keto-friendly!)
- Sodas and Juices
- Any other kind of sugar-filled Candy
Basically, you want to avoid any unnecessary foods that are full of sugars and starches. These foods are often much higher in the carbohydrate department.
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