Simply put, a ketogenic diet is a diet that’s low in carbohydrates, moderate in protein, and high in dietary fat. Originally, in the 1920s, a ketogenic diet was designed for patients with epilepsy to help reduce their seizures. The keto diet also tended to have positive effects on those patients’ body fat, blood sugar, cholesterol, and hunger levels. It has not been studied widely in terms of nutritional science.
To understand the keto diet weight loss, we’ve got to start from the beginning: calories and macros.
Calories are energy. It’s important to recognize that weight gain and weight loss are complicated.
“Calories in and calories out” is too simple and not accurate enough. Exercise is important for a healthy lifestyle, but it has minimal impact in terms of weight loss, while it does, of course, provide other health benefits.
Burning 300 calories in a workout doesn’t equate to burning off a cupcake. Nutrition is going to be about 90% responsible for changes in our bodies in terms of weight. And, different types of foods metabolize differently in the body.
There are many variables.
That’s why eating 2000 calories of fruit is not the same thing as eating 2000 calories of meat. Macronutrients consist of protein, carbohydrates, and fat. All calories come from these sources, with alcohol as the exception.
Your total calories for the day, no matter how many you eat and what diet you follow, equal 100%. Each of those macronutrients becomes a percentage of your daily pie, and the ratio will often change based on the diet.
You cannot have 100% of calories come from each macronutrient, that would be 300%. And because math exists,
that just isn’t possible. You can have an equal number of calories from each food—33.3%— but fat contains more calories per gram than protein or carbs, so the percentage would be different in that case.
A popular diet you may have heard on the internet is a High Carb, Low Fat diet, or 80/10/10.
That means 80% of calories come from carbs. Competitive bodybuilders often build muscle with a diet that’s higher in carbs and lower in fat with moderate protein, and then, closer to their competition when they need to lean out, protein becomes the biggest macronutrient in their diet, followed by fat and carbs.
A ketogenic diet, on the other hand, consists of a diet that is around 70% fat, a moderate amount of protein, and very little carbs, only 5% to 10%, depending on the person’s tolerance.
Now, it’s not a strict ratio, because it will vary from person to person. We all have a different carbohydrate tolerance and our insulin resistance levels are different, which means one person on a keto diet may be able to eat more carbs than another person on a keto diet but still be in what’s called “nutritional ketosis.”
Keto diet has a high-fat ratio
Now, I realize that this may sound very different from what most of us have been taught about nutrition. When I first heard about a keto diet and this high-fat ratio, I was skeptical. I had always been taught that you don’t want to eat a lot of fat! But a keto diet functions differently than some other common diets, such as a diet higher in carbs with less fat and protein that we are typically told is “healthy.”
It’s important to recognize from the beginning that there is no “right” or “wrong” ratio, but there may be one that works better for you and only you can find that out. So, we know that calories are fuel for our bodies, but that fuel can come from 1 of 2 main sources: glucose, or ketones.
The main one that most people function off of today is glucose. It can be a great energy source for the brain and body and comes primarily from carbohydrates. This is essentially a “sugar burning mode” since glucose is a sugar. The second source of fuel is ketones or ketone bodies.
A ketogenic diet is fueled by ketones
People on a ketogenic diet are fueled by ketones, rather than glucose. Ketones are produced when glucose levels fall, and the body has access to fat, either in the form of stored body fat or dietary fat.
When someone’s body uses ketones as fuel rather than glucose, they are in “nutritional ketosis” which
is like a “fat-burning mode” since fat is the fuel source. For any diet, it’s important to have both carbohydrates and fat for the body to function properly. However, it’s the amount of one relative to the other that will determine your fuel source, and one is no right or wrong.
Now, if glucose is available to the body, it will use that first, because it’s easy to burn up. If you eat a lot of carbohydrates, your body will use that glucose as its a fuel source, rather than using fats as fuel. This is why carbohydrate intake must be LOW on a ketogenic diet, and a keto diet is often referred to as a high-fat diet— dietary fat needs to be prevalent enough in the body in order to produce ketones.
Many people associate the word “fat” with the fat on our bodies and are unfamiliar with it as a fuel source.
There’s a lot of misunderstanding about how a ketogenic diet works, which is why there’s also a lot of criticism surrounding it.
Don’t get me wrong—our brains and bodies do need some glucose, just like we all need some dietary fat, But glucose does not need to be the main source of energy for a body to function healthily.
Glucose is one energy source, ketones are another— neither is “right” nor “wrong,” they’re just different. In fact, our ancestors may have lived ketogenic lifestyles without being aware of it. As hunters and gatherers, our ancestors ate lots of nuts, seeds, meats, and lower-carb fruits like berries.
This is often referred to as “primal eating,” and it’s a diet that was high in fats and low in carbohydrates. It likely resulted in ketosis and helped our ancestors survive from one meal to the next because their bodies could store that fat as energy. But, does that mean that they CHOSE to be in ketosis?
No, they would have eaten whatever was available to them, but the point is that it was a viable way for them to survive healthily, even if they didn’t understand the science behind it. When a lot of people hear about “primal” or “hunter-gatherer” eating these days, they think of the Paleo diet.
Now, is the paleo diet a ketogenic diet?
The answer: it can be.
On a paleo diet, you can eat
- Grass-fed meats,
On a paleo diet, you can’t eat
- Refined sugar
- Processed foods
- Excessive salt.
Now, most of that aligns with a keto diet, where one consumes more fat and fewer carbs. However, nothing is strictly prohibited on a keto diet.
The ultimate goal is a ratio of fats to carbohydrates— which likely means not consuming many if any, grains, legumes, or sugar regularly.
A paleo diet limits only the types of foods one can eat, and not the macronutrient amounts.
For instance, there is no limit to fruits or healthy carbs, and no minimum amount of fats. A paleo diet is not necessarily a ketogenic diet, although it can be. Does that make sense?
There are plenty of other diets that you may know of which can result in nutritional ketosis, they’re just not necessarily “keto” diets. For example, the Atkins Diet is a low-carb diet, so it’s commonly mistaken as a keto diet— but it’s not. It’s similar, but there is a significant difference, and it involves the one macronutrient we haven’t touched on yet: protein.
Both a ketogenic diet and the Atkins Diet are high in fat and low in carbohydrates, but a ketogenic diet is moderate in protein, while the Atkins diet does not set a limit to protein intake.
Why does this matter?
We talked about how carbohydrates are used by the body as fuel in the form of glucose, and fat is used as fuel in the form of ketones. But, what about protein? Well, through a process called gluconeogenesis, protein can also be converted into glucose.
This means if someone wants to experience the benefits of a ketogenic diet and be in a state of ketosis, even if they are on a diet that’s low enough in carbohydrates, their protein intake can throw them off because too much protein will be processed by the body as glucose.
On a ketogenic diet, just like with carbohydrates, the amount of protein one can consume will depend on the person and how their body metabolizes different foods. There are still benefits to diets like these, that are lower in carbs and contain fats, but lower carb does not equal ketosis, necessarily.
Ketosis is a physical, biological process that goes on in the body.
It’s brought on when the fat-to-carb ratio is just right— high enough fat, low enough carb—for THAT person’s body. If there isn’t enough fat, or if there is too much glucose or protein, which we now know can be converted into glucose, the body will use that glucose instead and be in a state of glycolysis, a.k.a. that sugar burning mode.
We’ve established that a keto diet exists, but why would someone want to be in ketosis?
What are the results of following a ketogenic diet?
Weight loss: In ketosis, the body is able to burn stored fat, and insulin levels are lowered since there is less glucose in the body.
Reduced appetite: Since fat is more satiating, people often don’t get as hungry on a ketogenic diet, which can improve a person’s relationship with food.
Mental clarity: People in ketosis often report experiencing a level of mental clarity that they don’t have when fueled by glucose.
Healing: Studies have also shown it can help kill cancer cells, and help to treat or even reverse cognitive
impairments like Atkins Diet
Improved insulin levels, reduced blood pressure, and improved blood cholesterol and triglyceride levels.
These benefits all result from fat being the body’s fuel source.
What types of fats are appropriate for a keto diet?
Now, this may seem a bit strange or confusing, because it will likely go against a lot of what you’ve been told about nutrition. A ketogenic diet is high in fat and low in carbs macro-wise, but most people who follow it also consider themselves on a whole foods diet.
They are eating lots of leafy and cruciferous veggies, grass-fed meat, eggs, wild-caught fish, dairy (depending on the person since it can be inflammatory), olive oil, coconut oil, grass-fed butter, avocado, nuts, seeds, and more!
People on a ketogenic diet would typically avoid the more obvious processed foods and grains, but they might also avoid some whole foods, such as sweet potatoes, quinoa, higher sugar fruits, legumes, etcetera because of their carbohydrate levels.
These whole foods are still perfectly healthy foods, they just won’t help with getting into ketosis. Too many carbs mean glucose is available to the body, which means it won’t produce ketones. For nutritional ketosis to happen, ketones need to be the available fuel source.
It’s a lot of information to process! But you see why it’s so important to stay open-minded. Really, there is no such thing as “good” or “bad” when it comes to health and nutrition because it’s all relative.
What’s good for one body can be different for another, especially when we’re running on different fuel sources!
There’s SO much talk in the nutrition world about fat, and saturated fat, in particular, being “bad,” but, again, this is relative. Everyone agrees that trans fats are bad, because they are unnatural, man-made fats.
But, new dietary research has caused some disagreement over saturated fats. Many things we’ve been told to avoid, like butter and meat, can be a healthy part of our diets if they are in fact grass-fed and not processed.
On a ketogenic diet, people are generally not discouraged from eating saturated fat in the form of grass-fed meat, grass-fed butter, healthy oils like coconut and olive oils, ghee, avocado, salmon and other fatty fish, eggs, nuts, seeds, and full-fat dairy.
On a standard low fat and higher carbohydrate diet, many of these items are discouraged.
Why is that?
The AHA and some dated research claim that saturated fat causes heart disease, but it’s come to light with recent research that that conclusion can’t really be drawn. It’s more likely that inflammation causes heart disease than saturated fats, specifically if those fats are from whole foods, and are nutritious dietary fats.
Remember you can only have 100% of your total macronutrients. So, if you are going to include more fats in your diet, the only option is to lower the protein or the carbs, regardless of keto or any other diet.
And this is where it can get tricky. We see it circulating around now that “fat is healthy” but we are also told to eat quinoa. You can’t eat a ton of fat AND a ton of carbs. Likely, this would just mean a person is consuming too much food in general. AND remember that fats are more calories per gram than carbs or protein, so LESS food adds up quickly in your total caloric intake needs.
There’s a lot to be mindful of with a ketogenic diet, but it can have its benefits.
So who might consider a keto diet?
We already mentioned a few:
People with a goal of weight loss: Some people who have struggled with insulin sensitivity and/or being overweight may find that a ketogenic diet works really well for them because they don’t have to deal with insulin.
People trying to reset their appetite center and be more mindful of being full: So if you’re on a low-fat diet, or low fat and low carb diet, or a high protein diet, and you think you’re really hungry all the time, you’re not crazy. You actually are hungry.
Your insulin is raised and it’s telling you that you need fuel. On a ketogenic diet, without the glucose there, your body doesn’t experience spikes in insulin and you’re more likely to feel satiated.
It may also help people with a goal of reducing blood pressure and finding healthy cholesterol levels, or people looking for help with PCOS treatment, or those with neurodegenerative disorders.
A ketogenic diet is not for everyone
It’s not appropriate for people with conditions like kidney or liver disease, Muscular Dystrophy, gallbladder disease, gastric bypass, rare metabolic disorders, pancreatic insufficiency, those prone to kidney stones, Type 1 diabetes, blood sugar issues like hypoglycemia—
So for people with type 2 diabetes, it depends and there are conflicting responses, so it’s best to get a doctor to supervise— those who are pregnant, nursing, or who have gestational diabetes, and it also may not be a good idea for people who have suffered from an eating disorder, people who have a history of mental health problems, children or people under the age of 18, and people who are naturally very thin with a BMI of less than 20.
And, of course, a general health screening is always a good idea to make sure there are no rare conditions or contradictions with your health or medications on a ketogenic diet.
Because the nutritional science world is still relatively new, like I said earlier, there isn’t a ton of information on keto diet results
New dietary research is emerging that’s challenging our old beliefs about nutrition. But, despite this, the old research that demonized fat and saturated fat is still widely accepted.
Most of what we know about ketogenic diets come from actual people who have put it into practice in their lives. There is not enough existing research yet to start changing our old approaches to nutrition in the medical world.
A ketogenic diet does go against much of what we’ve been told about nutrition in the past few years, but the science behind nutritional ketosis is still new. But just because the research doesn’t exist in the capacity that’s needed for all doctors to make new conclusions, doesn’t mean that this information isn’t true or that the lifestyle isn’t an option.
All accepted forms of medicine today, at some point, started out as “alternative medicine” that needed enough research to back it. For that reason, if you approach your traditional doctor about a ketogenic diet, I’m going to let you know upfront that he or she may just tell you to not do it.
Now, I will never tell you to not listen to your doctor, but I will encourage you to continue to do your own research so you feel confident making decisions because you know your body best. Even if you don’t feel the confidence right now, you do.
I do not recommend trying out a ketogenic diet willy-nilly.
You should be able to fully understand how ketosis works and why before making lifestyle changes.
This is just an introductory article to explain the diet, not an instructional one telling you how to start it. I don’t want you to miss out on valuable information that you wouldn’t have without doing your own research, like the stages of ketosis, the difference between ketosis and ketoacidosis, how to test ketone levels, supplements, salt intake, effects on exercise, water intake, etcetera— all of these things which are really essential to understand before making dietary changes.
Remember—the reason there is such a debate about these different diets. You can’t do all of them at once, so people tend to think that one is right or wrong.
But none of them is right or wrong, and they all work for someone, but they won’t all work for you. Probably. We all need to stop with this “this diet is right and this is wrong” and the “fat or carbs are good or bad” mentality.
It depends on you and your body and what works better for you.
You are not me or anyone else, we are all different. Our diet needs and what works for us will depend on our genetics, lifestyle, activity level, diet history and so much more.
So if someone gets on the internet and claims that any type of diet or ratio is the one for everyone, be skeptical because remember, they don’t know you, or your history, or your body, or what you might be sensitive to. Even if you have no interest in actually following a ketogenic diet, I think information is power.
It can help us to be more understanding of other lifestyle choices, and knowing what it is and how it works will only make you a more informed human. The more you know about your body and how it works, the more confident you’ll feel to make your own choices moving forward.
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