Is Keto the Best Diet for Weight Loss?
The ketogenic diet is a low carb, high-fat diet that was first discovered in the 1920s for its ability to mimic fasting and treat pediatric drug-resistant epilepsy. While the development of better anti-epileptic drugs led to a temporary downfall for the ketogenic diet, the diet has resurfaced in the last couple of decades as a potent weight loss and disease management diet.
The ketogenic (keto) diet has a lot to offer in terms of improving overall health and wellness but there is no denying, the diet’s most robust benefit is weight loss. In this article, I will dive into the truth about the ketogenic diet and weight loss.
How Does Keto Promote Weight Loss?
What gives keto such a potent weight loss capability is the different mechanisms in which keto can contribute to weight loss. This is also what allows keto to demonstrate weight loss in both the short term and the long term.
In the short term, weight loss is typically very rapid. Many people report losing up to 6-8 pounds during their first week on keto. While some of this initial weight loss is a result of burning fat, much of this is a result of changes occurring as your body adapts to a ketogenic diet.
During the keto adaptation period, your body is transitioning from burning carbs as a primary energy source to burning fat and producing and utilizing ketones. One change that occurs during this time is lower insulin levels which stimulates your kidney’s to release more water which not only makes you prone to dehydration and electrolyte deficiency but also rapid weight loss.
In addition to water loss at the beginning of keto, glycogen is also a source of some of the initial rapid weight loss. Glycogen is the stored form of carbohydrates found primarily in our muscles and in our liver. Glycogen is a fuel reserve for working muscles that is depleted when first starting a keto diet thus contributing to total weight loss.
The reason I chose to inform you about this initial rapid weight loss is because it does not continue to occur and this causes many new keto dieters to become discouraged or think they have hit a plateau. The truth is that the body has just adapted more and is now losing weight in a slower and much more sustainable manner
In case that last part bummed you out a little bit, I want to let you know that when you do get adapted to keto, while you may not necessarily be losing 8 pounds a week, you will be burning through some serious fat!
How Does Fat Burning Occur on Keto?
The way a ketogenic diet promotes fat burning is similar to that of fasting and is one of the reasons for the similarities between these two health strategies.
When you are on a ketogenic diet, you are making changes in your body that promote fat burning. When you are not eating carbs, you blood glucose and insulin go down. This causes your pancreas to secrete another hormone called glucagon which can interact with our stored fat tissue to stimulate the release of stored fat into the blood stream where it can be used for energy or shuttled towards ketone production. Boom, thats fat burning on keto.
One thing many of those who are not proponents of keto will bring up at this point is that none of this matters because what matters for weight loss is calorie restriction. While calorie intake is definitely a key factor in weight loss, the research just doesn’t agree that it is the only think that matters.
Aren’t Calories All That Matter?
Weight loss is just calories in vs. calories out right? Not quite guys. This is far too simplistic of an understanding for such a complex biological system, but don’t take my word for it. Let’s see what the research says:
As you can see, this study compared 4 very different diets (1). While each diet did consume nearly the same total calorie intake, they consumed a different macronutrient ratios and as you can see, the results were not the same for each diet.
The Atkins diet, which closely resembles keto in its degree of carbohydrate restriction, demonstrated much greater not only weight loss but percentage of body fat lost. Why did this happen guys? Because what you put in your body matters. The macronutrient and micronutrient makeup of your diet plays a big role in the success of the diet and this study makes that very apparent.
I want to take this time to point out another thing. Even this study could be flawed because of the simple fact of subject variability. Every subject is different and has a different biological makeup that changes the way the foods they eat will interact in their body and that is one of the things that makes interpreting nutrition research so difficult.
Why research is confusing
The truth is that you can find just as many studies that do not demonstrate keto as being superior for weight loss as you can find that does. To help you understand what’s going on with this, let’s take a quick step back to understand why interpreting nutrition research can be so complicated.
As I mentioned earlier, each subject has a different biological system and this means that the way their body responds to a diet is going to be different. While some studies try to control for as much subject variability as they can, it is simply not possible to be perfect. The reason why this matters is because the internal environment of your body determines how it will respond to the foods you are ingesting. Think of it like this. If you put oil in a hot pan it sizzles and if you put it in water it separates and sits on top. The point here is that the environment plays a role in the action taken by the oil. This is similar to what happen inside your body.
If someone is insulin resistant and full of inflammation (which most obese people are), then the truth is that carbohydrates are not well tolerated by that person. For this reason, a diet low in carbs is probably going to be better for them. If you are a lean individual who is insulin sensitive, then your body probably handles carbohydrates pretty well so a diet low in carbs may not be any better for you, in terms of weight loss. Improving overall health is a whole other story!
The reason why I bring that up is because if you look at studies comparing various diets on weight loss, the subject types matter. Most studies with obese subject show better weight loss on a low carb diet while leaner and healthier subjects may not see the same differences. This is important to consider when interpreting research.
Another reason why interpreting research on weight loss on a keto diet is difficult is because not all studies test the composition of the weight being lost. Some studies do demonstrate similar amounts of weight lost between keto and other diets but in most cases if that weight lost is measured, it is found that low carb keto diets tend to have a higher percentage of weight lost from fat and less from muscle compared to other diets. Why does this happen? Well it may just be because the degree of carb restriction matters. Check out this study below:
This awesome study looked at the effect different levels of carb restriction had on things like fat loss and ketone levels (2). As you can see, the greater carbs were restricted, the greater the fat loss. Since calories weren’t significantly different between groups this further supports my outlook of calories in and calories out for weight loss being far too simplistic.
Besides greater fat loss, greater carb restriction also seems to correlate with increased ketone levels. Ketones, the molecules produced to help replace carbs as the body’s primary fuel source, are able to provide the body with many benefits, one of which is muscle preserving, which we will get more into in a second but is a reason for the differences found in composition of weight loss from diet to diet.
You may be guessing that I am a little biased to keto for weight loss. I am, and it’s because I think it is by far the superior option for weight loss.
Why is Keto superior for weight loss?
Better fat burning
As I mentioned earlier in this article, cutting carbs causes your blood glucose and insulin to be low which literally puts the body in a position where it needs to turn to stored fat as an energy source. This is a lot different from a higher carbohydrate based diet where frequent spikes of blood glucose and insulin would essentially kick you out of fat burning mode for a period of time that depends on the individual. When blood glucose and insulin are high, as they would be after a carb containing meal, then the body does not need to burn fat for fuel and fat burning is temporarily blunted.
The length of time it takes you to get back into fat burning mode is likely dependent on your degree of insulin sensitivity. If you are extremely insulin resistant than chances are consuming carbs could keep you out of fat burning mode for a while. This is probably why keto shows better fat loss results in this population especially.
Research has found that ketones can slow the breakdown of the primary muscle protein, leucine, which is one of the reasons why we see that more muscle is maintained on a keto diet compared to other diets which is also the cause of different composition of weight lost for various diets (3). It is easy to lose muscle when you are dieting and especially in a calorie deficit. Ketones produced on a keto diet can help prevent this.
Keto is also superior for weight loss because the diet can actually lead to improved health. Many weight loss diets are so restricted that are way too low calorie, do not focus on food quality, and metabolically damage whoever follows them. A keto diet, if done right, will improve your health through many factors with two of the most importantly being reducing inflammation and insulin resistance, two of the biggest contributors to today’s most popular chronic diseases.
To learn more about the benefits of ketosis, check out What is Ketosis?
Maintaining weight loss
Another reason why a keto diet may be superior for weight loss is the diets ability to help maintain weight loss. Check out this study below:
This study demonstrated something that is very unique to a keto diet and that is the prevention of increased hunger hormones when dieting (4). Typically, when we are calorie restricted and dieting, especially for a long time, our bodies respond by increasing hunger hormones. However, a pretty strong amount of research has found that this increase in hunger signaling does not occur on a keto diet which may make keeping off all the weight lost on the diet!
To conclude, the keto diet is without a doubt one of the best approaches to losing weight. It allows you to still quickly lose weight without having to sacrifice your health or your relationship with food. If you are new to keto and you are looking for an easy way to start, check out a program I made with Dr. Anthony Gustin and Jane Downs called the Keto Kickstart! If you are looking to learn more about keto, check out my article What is Keto.