There are many different diet types out there and some of them are supposed to be revolutionary for weight loss. Today, I want to talk about one specific type, a ketogenic diet. This is a specific form of a low carb diet and one that has become exceptionally popular.
That’s really not surprising, as ketogenic diets have been linked to health benefits and also substantial weight loss.
But, how does a ketogenic diet work?
After all, it’s no good simply claiming that a diet works. Most diets work to some degree for a short time. So, what is it that makes a ketogenic diet special?
Well, to understand that, we have to take a look at the science behind this type of diet.
Before we get started, I do want to say that ketosis is a little complicated. In this post, I’m going to provide an overview of the diet, including how it works and the benefits that it offers. But, I’m going to avoid going too deeply into the complexity of the diet, as that information can get confusing quickly.
Nevertheless, this post will still answer the question, how does a ketogenic diet work.
What is the Ketogenic Diet?
Ketogenic diets actually come under a few different names. For example, you may sometimes hear it called a ketosis diet or even just a keto diet. These names all refer to the same concept, they’re just different terms that are used.
The names are all based on the concept of ketosis.
In some cases, you may also hear the name nutritional ketosis or nutritional ketosis diet. That term still means the same thing and it’s mostly just a clarification.
All of these various names come from the same underlying concept, the idea of ketosis.
Ketosis is a specific metabolic state where your body is operating in a different way. Specifically, the body produces ketone bodies (or ketones), including acetone and acetoacetic acid (1).
These compounds happen when the body does not have enough glucose to use as an energy source. So, it begins to break down fat instead, which leads to the production and use of ketones as an alternative source of energy (2).
Basically, the process is a survival mechanism, ensuring that people can still get the energy they need even when they’re not getting glucose.
Needless to say, the key advantage of the process is that you’re burning fat for energy.
This can easily contribute to weight loss, along with health benefits – and I’ll go into both of those areas later on in this discussion.
With these benefits, it isn’t surprising that ketosis is a popular concept. In theory, ketosis could make it easier to lose weight. This may be a key reason why the terms ‘keto diet’ and ‘ketogenic diet’ have been increasingly popular. These are shown below in blue and red, respectively.
But, to take advantage of this mechanism, you have to be able to get into ketosis and stay there.
This is where a ketogenic diet comes in.
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How Does the Ketogenic Diet Work?
A ketogenic diet offers a way to take advantage of the process of ketosis, while still getting the nutrition that your body needs. To do so, this type of diet means that you get the majority of your energy from fat, rather than from carbs.
In fact, to enter into ketosis you have to get your carb intake low enough that your body can’t rely on carbs for energy.
Now, there isn’t a magic number for achieving this. Instead, it varies from person to person.
But, a good general starting point is that you want to be having less than 50 grams of carbs per day.
Some people may be able to have more than that and still be in ketosis, while others may need less.
There are some key signs of being in ketosis that you can use to make sure you remain in that state. One of the most obvious examples of this is fruity breath, especially early on. Additionally, there are various tests out there to look at ketone levels in your blood, breath and urine.
You can also use weight loss as an indicator, although I wouldn’t recommend it.
After all, a ketogenic diet does normally involve changing up what you’re eating. So, the change in food alone could be causing weight loss, rather than ketosis.
The idea with a ketogenic diet is that you consistently keep your carb levels extremely low. Doing so keeps you in ketosis and lets you gain the various weight loss and metabolic advantages that come with doing so.
So, that’s the basic answer to the question, how does the ketogenic diet work.
There is more science that I could go into, including the role of ATP and the Citric Acid Cycle (3). But, I’m not going to. We’ve already covered the basics of the diet and if you want to know more you can look at my discussion on ketosis safety.
On a ketogenic diet, you keep your carb intake extremely low so that your body will enter ketosis and stay there
The Concept of Nutritional Ketosis
Earlier on, I mentioned that ketosis is sometimes called nutritional ketosis. That distinction is often ignored in conversations about the ketogenic diet simply because it is assumed that everybody is talking about nutritional ketosis.
However, there is a second form of ketosis, which is also called ketoacidosis.
This process is similar because it results in the production of ketones as well. But, the underlying mechanism is very different and this is a dangerous condition. Specifically, ketoacidosis occurs when there isn’t enough insulin in the body. This can happen when a person has uncontrolled diabetes.
In this situation, there is glucose available to act as fuel but the lack of insulin limits the body’s ability to process that glucose. As such, ketoacidosis leads to high levels of fat metabolism, which then produces excessively high amounts of ketones.
This pattern is why people experience unexplained weight loss when they have undiagnosed type 1 diabetes.
On average, you might release 1 to 8 mmol/L of ketones under a ketogenic diet. But, under ketoacidosis, a person produces more than 20 mmol/L of ketones (4).
The high level of ketones along with the blood sugar levels creates a dangerous situation in the body. In particular, ketones are slightly acidic. This acidity is not a major issue with a ketogenic diet. However, the levels of ketones are much higher with ketoacidosis, so the implications are more significant.
As such, nutritional ketosis can be a healthy approach, mostly because it is controlled ketosis and there isn’t a buildup of sugars. But, ketoacidosis is dangerous, so it’s important to be aware of the difference.
One alternative form of ketosis occurs in people with type 1 diabetes and is called ketoacidosis. This is a dangerous state where ketone levels are extremely high
Challenges of a Ketogenic Diet
Many people find that ketogenic diet is fairly easy to follow. One reason for this is that you’re relying on fat as an energy source. Foods that are high in fat are often filling, partly because they tend to have significant levels of protein as well.
However, a ketogenic diet tends to be fairly difficult when you first get started.
This happens because our bodies will preferentially burn carbs. So, when you switch over to an entirely different energy source, it can take some time to adjust.
This effect is sometimes called the ‘low carb flu’ and it may last a few days, for most people.
However, some people can experience issues for a longer period of time and it can take a month until your body has fully adapted to the change in energy source.
In the long-term, ketosis can be effective and many people find it easy to follow. But, it can be difficult at first, as your body is adjusting to a new energy source
What Can You Eat on a Ketogenic Diet?
Essentially, a ketogenic diet is a variation of a low carb diet. In particular, you’re trying to get your carb intake low enough to get into ketosis and stay there.
This means that you have to pay close attention to the food that you eat and the amount of carbs that it contains. At the same time, you also need to make sure you’re getting enough nutrients.
Now, the whole idea of a ketogenic diet is that you’re burning fat instead of carbs. This means that you also need to be eating fats rather than carbs.
Fats are starting to become popular again as science continues to show that they aren’t nearly as unhealthy as we once assumed. In fact, the entire cholesterol controversy and demonization of fat was based on some fairly shaky science, industry spending and a range of assumptions.
Instead, fat can actually be a healthy addition to your diet, especially if you focus on eating good quality fats.
So, with a ketogenic diet, you’re heavily relying on fat. This includes a strong emphasis on meat, particularly meat that has been grass fed and also on fish. However, you do want to avoid processed meat, along with any meat served in a starchy or sugary source.
In many ways, the challenge of a ketogenic diet isn’t what you eat but what you can’t eat.
Avoiding the obvious sources of carbs (like bread and pasta) is simple enough but there are many less obvious ones to consider too.
For example, many processed foods contain carbs that you might not expect, particularly because sugar keeps getting added where it isn’t needed.
You will even find unexpected carbs in natural foods too. For example, you need to be careful about the specific vegetables you eat and how much of them you consume. You need to be even more wary about fruit because most fruits are relatively high in sugar.
Additionally, be careful about any foods marketed as low-fat. Realistically, you’re not trying to avoid fat on a ketogenic diet. Plus, low-fat products typically have added sugar to ensure the end product still tastes good.
There is a very good list of foods to eat and to avoid over at the site Keto Diet Blog and I recommend checking that out for more details. However, it is important to note that this list (like most) includes some recommendations based on the author’s own beliefs, rather than ketogenic requirements.
To stay in ketosis, you need to focus on avoiding carbs. This means that you end up with a diet that is high in fat and fairly high in protein
Ketogenic Diets, Weight Loss and Health Benefits
For most people, the main appeal of a ketogenic diet is weight loss. After all, this is a diet that allows you to burn fat, which has got to be a good thing. So, how does the evidence stack up?
Well, there have been a number of studies showing that ketogenic diets can truly help people to lose weight. Additionally, some studies have shown that ketogenic diets can contribute to more weight loss than the typical low-fat diet (5).
One study also showed that a low-carb diet was more effective for weight loss than following healthy eating recommendations typically given to diabetics (6). However, that study focused on low carb in general, rather than ketosis.
Other studies have also found a similar outcome, indicating that low carb or ketosis diets are as effective or more effective than other diet types for weight loss. Likewise, in many cases, participants on the low-carb or ketosis diet had better metabolic outcomes (7, 8, 9,10,11).
Now, some researchers argue that the weight loss advantage is partly connected to the higher levels of protein in a ketogenic diet. That protein can help people to feel full and may mean that they eat less in subsequent meals (12).
However, other researchers argue that aspects of ketosis specifically may also play a role in weight loss (13). For example, one short-term study found that high-protein ketogenic diets had a greater impact on hunger and food intake than high-protein diets with medium levels of carbohydrate intake (14).
It seems likely that the effect of ketogenic diets on weight loss is partly connected to the protein and also to the metabolic impacts of the diet. But, in some ways, this doesn’t matter.
After all, research shows that ketogenic diets are effective for weight loss and can work better than other types of diets.
This alone is a good reason to stop asking ‘how does a ketogenic diet work’ and actually try it out for yourself.
Research indicates that ketogenic diets can be effective for weight loss. In fact, they can even have better outcomes than other types of diets
The Health Benefits of Ketogenic Diets
Beyond weight loss, there are a few other key advantages of ketogenic diets.
One of these is that they serve to lower insulin levels (15), which is appealing for most of the population. On a side note, the impact of ketosis on insulin levels does mean that you probably shouldn’t follow a ketosis diet if you have type 1 diabetes, although the diet works well for people with type 2 diabetes (16).
Likewise, a ketogenic diet can help to lower blood sugar levels in patients with type 2 diabetes (17).
At the same time, these diets can also help to improve lipid profiles, potentially decreasing the risk of heart disease and other related health issues (18,19,20,21). This may make ketogenic diets particularly relevant for people with abnormal lipid profiles and those who are at risk of heart disease.
The ketones that are produced with this type of diet may also have therapeutic benefits (22). The most significant example of this is the way that ketogenic diets can be used as a therapy for epilepsy. They can be incredibly effective in this role, to the extent of removing the need for medication (23).
Additionally, a ketogenic diet tends to result in a movement away from foods that are heavily processed or high in sugar and towards foods that tend to be less processed and more natural. This change in eating patterns can also contribute to health benefits and to weight loss (24).
Ketogenic diets have also been connected to other health benefits, including improved lipid profiles and decreased insulin levels. Plus, a ketogenic diet typically means that you are eating healthier food overall, which can also contribute to health benefits
Should You Follow a Ketogenic Diet?
Research and testimonials strongly support the idea that a ketogenic diet is effective, both for weight loss and for health. The diet can also be fairly easy to follow, especially once your body adjusts to the change in energy source.
After all, you don’t have to count calories. Many people also say that they feel like they have more energy following a ketogenic diet. Now, ketosis can feel restrictive but there are still some amazing recipes that you can create and still stay within the parameters of the diet.
But, a ketogenic diet isn’t necessarily the answer for everybody.
For example, some people might struggle to constantly steer clear of carbs, especially if they are particularly fond of bread and pasta.
Likewise, a ketosis diet cuts out a lot of conventional foods. This can make it harder to eat out and to buy or make food quickly.
This can be a limiting factor for people who are short on time or money.
From my own experience and from what I’ve learned, I believe that the ketogenic diet is worth that tradeoff.
However, if you want to lose weight effectively then you have to find a method that works for you and for your lifestyle. For many people, the answer may be ketosis and it’s certainly worth trying out the diet to see whether it is a good fit.
More than anything, the solution to long-term weight loss is to figure out a lifestyle that you can stick to. This means that you need to find something that you can still follow a year or two years from now, rather than a fad diet that may help you lose weight fast but won’t help you keep it off.
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What is your experience with ketosis? Have you ever tried the diet and, if so, did it work for you?