What makes a keto diet unique compared to any other weight loss trend that we've seen is a measurable shift in your metabolism - switching from carbs to fat as your primary source of fuel, using ketones.
While the ability to change up your metabolism sounds exciting, ketone bodies aren’t as new of a phenomenon as one might think. You’ve probably been producing them for years already. But the real questions remain - what are the real life benefits and risks of increasing your ketone production?
First, What is Glucose?
When you eat carbs, they are broken down into a form of usable fuel called glucose.
Glucose is a sugar that can be used for immediate energy, supplied to the blood to regulate blood sugar levels or stored in your muscle, liver or fat cells to be used later.
But glucose is important for more than just quick energy. It is also the only source of fuel that is able to cross the blood-brain barrier. In other words, your brain loves carbs. This is another reason why your body prefers this macro for fuel. Additionally, because glucose is the type of sugar found in your blood - it is clearly important for maintaining blood sugar control, and pretty impossible to survive without it.
Without carbs, your body has to find other ways to get glucose or find some other usable form of energy that is efficient and able to supply your brain with fuel - enter ketones.
What are Ketones?
Ketones or ketone bodies are acidic molecules produced by your liver when carbohydrates are not readily available for energy.
In other words, when you cut carb intake to very low intakes (less than 5% of your calories) or through periods of fasting, your body runs out of glucose (sugar) and glycogen (the storage from of carbs or sugars) and is forced to find an alternative source that can provide quick energy and fuel your brain properly.
The primary building block of ketones or ketone bodies is fatty acids - from either stored or dietary fat. Your liver is able to break down fat to produce three types of ketone bodies.
- Acetoacetate - the main ketone produced. It is either used for energy, converted into Beta-hydroxybutyrate, or excreted through urine (you can test for acetoacetate with keto test strips!).
- Beta-hydroxybutyrate (BHB) - used as fuel by the body and brain. Reaching higher BHB levels is often a key desired result of ketosis.
- Acetone - produced in small quantities and not readily used by the body. A majority is excreted through breath, resulting in a fruity, keto breath.
How Your Body Makes Ketones
Ketones are produced through a process called ketogenesis when the need to use fatty acids for fuel increases - or when quick sources of glucose become limited.
It is thought that when you start producing enough ketones that they become your primary source of fuel for your muscles and organs that you enter a state known as "nutritional ketosis".
Ketosis is the metabolic state desired by most low carb, keto dieters who are looking to increase their body's ability to burn or utilize fat for energy.
Getting into ketosis is not an easy feat for everyone and can take multiple weeks depending on your training, glycogen stores, and your body's ability to use fat efficiently.
Fat vs. Ketones for Fuel
Using fat for fuel is often used interchangeably with using ketones, but this is not exactly the same thing. Even when you are eating a lot of carbs in your diet, you can still use fat (and do quite frequently!) as a source of energy without needing to go into ketosis.
The type of fat you are using for this is primarily coming from stored fat (fatty acids). Stored fat is actually a preferred source of energy in-between meals, during rest, and after long duration exercise.
Your body has an almost unlimited capacity to store and use fat compared to carbs, as we’ve seen with the obesity epidemic. And using fat gives you twice as much energy for the same amount of work (one gram of fat is 9 calories whether you eat it or burn it, compared to carbs that provide only 4 calories a gram) – making it a desirable source of fuel.
Ketones, on the other hand, are created when there aren’t enough carbs or glucose available. And even though ketones can be used in a similar way as stored fat, they differ from traditional fatty acids because they can be used instead of carbs as a quick source of fuel and a way to provide energy to your brain and other organs that traditionally rely on glucose. In other words, ketones are your body’s way of replacing glucose with fatty acids.
Are Ketones Safe?
For most people, producing small amounts of ketone bodies is perfectly safe and can even be desirable.
Every living animal possesses the capability of switching from sugar to ketones for fuel. However, ketones are not the preferred source of energy by many of the body’s organs when carbohydrates are available.
Most healthy adults make small amounts of ketones for energy on a regular basis. This occurs mostly in times of fasting, like between meals or overnight while you sleep (1).
What About Exogenous Ketones?
You might have also heard of exogenous ketones. These are ketones available in a supplement form that can be used for energy without requiring you to go on a keto diet.
Some research suggests taking ketones alone can promote ketosis (2,3). In addition, ketone supplements are thought to increase the rate at which ketosis occurs on a keto diet and promote better energy control for workouts while going through the process.
However, while supplements like this are interesting, there is still much more research needed to identify any potential risks or benefits. Not to mention, exogenous ketone bodies don't outweigh the need for calorie control and better nutrition.
3 Possible Benefits of Ketone Production
The original intention of a ketogenic diet came about in the early 1900s as a way to help control seizures in kids with epilepsy. Since then, many low carb advocates have praised a ketogenic diet for a variety of potential health outcomes.
However, while many of these benefits are interesting to consider, most are not heavily supported by science. Much more research is still needed to determine whether metabolizing ketones can improve your health or ability to lose weight.
Here are 3 possible benefits to know:
1. Producing Ketones Might Help You Burn More Fat
Getting into ketosis shifts the body to increased fat burning capabilities, which theoretically can result in increased fat loss (4). Additionally, using fat or protein for fuel requires the body to work harder than when utilizing carbs, which in turn may cause your metabolism to increase slightly (5,6).
However, burning fat does not always equate to losing body fat - unless you are in a calorie deficit. In fact, if your calorie intake exceeds your calories burned, you will continue to store fat regardless of how much fat you are breaking down for energy - and can actually gain weight in the process.
2. Ketones Can Support Endurance Training
If you love to run, cycle, or take long hikes, getting into ketosis may have some serious benefits for your energy and fitness stamina.
Endurance training and a ketogenic diet may be a match made in heaven. That's because relying on fat or ketones means you can store more energy and may not need to work as hard to get it - helping you go for longer. Fat is energy abundant (providing twice as many calories as carbs per gram) and you are able to store more fat than other sources of fuel, like carbs.
It's no surprise that cyclists, runners, and other endurance athletes have found a keto diet to be extremely useful towards their performance (8,9,10). In one study ketone bodies supplied 31% more energy than pyruvate from glucose (11).
However, a keto diet does not eliminate the need for nutritional support during longer training. Electrolyte balance, hydration, and overall calorie needs are still an essential part of endurance and stored fuel will only get you so far. You will still need to support and replenish when exercising for more than 60 to 90 minutes at a time.
In addition, for competitive athletes, decreased glycogen stores may inhibit your ability to all-out sprint to the finish or go for that final push.
3. Ketones May Support Brain Health
Because of ketones ability to cross the blood brain barrier and its history of being used to treat epilepsy in children, there are a variety of theories and claims around its potential benefit to brain health and function (12). Neurological conditions like Alzheimer’s Disease, Parkinson’s Disease, traumatic brain injury, and stroke have all been suggested to benefit from the keto diet.
However, it’s critical to not equate these early theories and associations with causation or cures. Only limited research exists from animal studies and uncontrolled studies in humans looking at a keto diet for possible treatment of other neurologic disorders (13).
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2 Potential Risks and Pitfalls of High ketones
While the potential benefits of producing more ketones can seem enticing, switching from sugar to ketone bodies for fuel isn't ideal for everyone, specifically certain athletes and Type 1 Diabetics.
Here are two potential risk or pitfalls to be aware of:
4. Ketones Can’t Replace Glucose Entirely in Fitness
Ketones cannot supply 100% of your energy needs - some glucose is still needed to support certain organs and balance blood sugar levels.
This is also true when it comes to certain types of fitness - like heavy strength training and high intensity training where ketones just can't quite stack up to glucose as a source of quick fuel (14,15,16).
Using fat for energy is typically a slow process that requires adequate oxygen supply. While this type of fuel may be a meaningful choice for endurance athletes and those participating in lower intensity training, it may not cut it for anything that requires explosive movements or anaerobic exercise.
As intensity increases and oxygen consumption increases, your body needs energy more quickly. And even though ketosis is thought to improve your body's ability to use fat for energy at higher outputs through keto-adaption, this increase still may not be enough to fuel all of your high-intensity training (17,18,19,20,21).
If you enjoy high intensity training or find your workouts suffering on a low carb, keto diet, you may want to consider adjusting your carb intake accordingly to support your fitness goals.
5. High Ketone Levels Can Be Dangerous for Diabetics
High amounts of ketones in the blood can be dangerous if you are Type 1 Diabetic. People with Type 1 Diabetes can develop diabetic ketoacidosis if their blood levels of ketones become dangerously high (>10mmol/L). This makes it especially important for people with type 1 diabetes to work closely with their doctor before starting a keto diet - and it is often recommended that they have a higher carb intake (>50grams/day) to prevent dangerous complications.
Increasing ketone production can also be dangerous for any Diabetic who is taking medication to manage their blood sugar levels. If you are taking medications designed to decrease blood sugar levels, and you suddenly decrease carbohydrate intake to very low levels, your blood glucose can drop dangerously low resulting in hypoglycemia - and this can even be deadly.
Is Ketosis Right for You?
The process of getting into ketosis is different for everyone and also may not be the right fit for every person. But there are still some notable benefits to utilizing more fat for fuel in the form of ketone bodies.
Still not sure if a keto diet is right for you? Take our five minute quiz and we will match you with the diet style that best fits your goals and tastebuds.