The keto ( or ketogenic) diet is one of the hottest nutrition topics in circulation today.
It is gaining increasing notoriety for its alleged health benefits, including a supposed ability to confer people with superior weight loss results as compared to a balanced, inclusive diet.
Before we get into all that though, let’s breakdown the keto diet into its distinguishing trait – ultra low in carbohydrates.
The keto diet is essentially the ultimate low carbohydrate diet
In fact, the premise of the diet is that you consume so few carbohydrates that your body alters its energy metabolism to prefer the use of fat (in the form of ketones- hence the name ketosis) for fuel instead.
Why do people try the keto diet?
Why do people try any diet? They read about it online, someone famous does it, a study comes out on it, they think it will help them improve their health or lose some weight.
There were a NUMBER of facets that I could have potentially explored in today’s article, but I’ve chosen specifically to focus in on weight loss, as I believe that would represent the biggest motivation for an “average person” to go out on a limb and try the keto diet.
I will not be touching on the evidence pertaining to the ketogenic diet’s potential effects on other health outcomes ( such as diabetes, cardiovascular health, seizures in children etc).
The Keto Diet: Characterized
For the sake of today’s article the most important thing you need to know about the keto diet is that it is ultra low carbohydrate and calls for a macronutrient calorie distribution of approximately the following:
Fat: 70-80% ( 20-35%)
Protein: 20-25% ( 10-35%)
Carbohydrate: 5-10% ( 45-65%)
(Standard “acceptable” ranges in parentheses)
Upon a quick glance you can see that the ketogenic diet essentially swaps out dietary carbohydrates for dietary fat.
It also means that nutrient dense dietary staples such as fruits, starchy vegetables and whole grains are essentially out of the question because there are simply not enough carbs to go around.
This is obviously an immediate point of concern because we know that the consumption of those foods is generally associated with longevity and reduced chronic disease risk.
From a “keto diet for weight loss” perspective however…
Some researchers hypothesize that carbohydrate restriction and the presence of ketones may contribute to a cascade effect of reduced hunger/appetite and an increase in metabolism owing to the energy required for your body to use fat as energy.
But what does the best available experimental evidence have to say?
Will The Keto Diet Help You Lose Weight Better Than A More Balanced Approach?
That is the million dollar question for today… and not necessarily a very easy one to answer given the limited amount of high quality evidence currently available on this topic.
I went on the hunt for reasonable quality studies published in the last 5 years that looked at the ketogenic diet’s effects on weight loss when compared to more “normal” eating patterns..
I quickly happened upon a Meta-Analysis of controlled trials from 2013 published in the British Journal Of Nutrition by Bueno et al that found that, compared to a more standard dietary pattern, the ketogenic diet was conducive to small improvements in weight loss ( a few %, but statistically significant) within the first year but that longer-term ( >1 year) adherence was problematic and the difference in weight loss effect diminished with time.
I then discovered what appeared to be one of the most recently published randomized controlled trials available and decided to took a MUCH closer look at its finer points to see what I could learn about how these types studies were being conducted.
The study that I am referring was done in 2014 by Moreno et al.
They compared what they described as a very low calorie ketogenic diet to a “standard” low calorie diet.
They found that, in their group of obese patients, the ketogenic diet was signiﬁcantly more effective than a standard diet when it came to weight loss over a 12 month period.
But there was more to their approach than meets the eye.
When I reviewed the study methodology more closely, this is what I found:
1. The standard diet was offered in the range of 1,400-1,800 calories using reasonable macronutrient distributions ( Carbs: 45-65%, Fat: 25-35%, Protein: 15-25%)
2. The ketogenic diet was rolled out far more elaborately in three evolving phases. Starting with a very low calorie diet that was primarily protein to induce rapid weight loss (in the 600-800 calorie range) in the first two months before ultimately transitioning into a balanced non-ketogenic 1500-2000 calorie diet in the longer term.
The author’s suggest that the rapid early weight loss offered encouragement to the ketogenic diet group and contributed to their prolonged success when compared to those on the standard diet.
I chose to focus on this particular study because if the average person were to google “randomized controlled trial keto diet” this is probably the article they would be likely to encounter and I would not be surprised if it is referenced by numerous pro ketogenic websites either.
But the manner in which this study compares the weight loss effects of a ketogenic and standard diet appears to be quite irrelevant to what I would feel the “average” person perceives the keto diet to be ( consistently high fat, low carb).
In fact, the first phase of the ketogenic diet applied in this study was low carb, low, fat and high protein… and was much lower in calories than what the standard diet group was getting!
It was in this period of time of caloric disparity that most of the weight was lost in the experimental group…
To be more concise: This study does NOT compare a static keto diet and a static standard diet of the same caloric value over a period of time to see which one leads to more weight loss ( although if someone read the abstract exclusively they may be lead to believe that).
This study compares a static “standard” diet with what appears to be an elaborately rolled out three-phase ketogenic diet that ultimately evolves back into a carbohydrate rich diet and ends up being a pretty complex intervention overall.
I simply cannot imagine the average citizen implementing a keto diet in this way when they decide to “give it a shot for weight loss”.
With That Being Said
In my admittedly limited exposure, I have identified what seems to be a bit of a trend in the keto literature whereby the ketogenic diet is used as a means to “kick-start” weight loss before transitioning into a moderate balanced diet.
That was certainly the case in the example above, and it appears that researchers out of Italy ( Paoli et al 2013) had weight loss success using an initial ketogenic diet that transitioned into a more sustainable mediterranean dietary pattern.
That seems a much more reasonable and practical use of the approach, if one were to use it at all.
#1 I am not a keto diet expert, I reviewed a few pieces of important literature in order to create today’s article.
#2 The available high quality evidence that I had to choose from was very limited because it simply does not exist.
I carried out a very focused task to explore just one of the many hot topics within the keto diet realm ( keto for weight loss).
My findings suggest that, within the better quality research being shared comparing ketogenic and “standard” diets, there is only limited evidence to justify someone using a ketogenic diet for enhanced weight loss and it certainly appears that the successful usage of the diet has been a bit more complicated than just switching out carbohydrates for fat and calling it a day.
Having said that…
If you have had success on the ketogenic diet, all the power to you and I take NOTHING away from your experience.
As a dietitian who preaches balance and dietary inclusivity, it’s not an approach that really resonates with me BUT…
For anyone out there who has had limited success losing weight through more conventional means ( including with the help of a dietitian of course!), you would not be completely unjustified in considering the ketogenic approach in the short-term.
Despite the fact that I don’t necessarily love, support or advocate for the keto diet ( especially in the medium to long-term), it cannot be ruled out as a potential weight loss aid for curious individuals who have struggled to succeed with other approaches.
My only request is that, if you are enamoured with the idea of trying this diet, you should seek out appropriate professional guidance to ensure safety and nutritional adequacy while you attempt what is, undoubtedly, a very restrictive diet and one that has many more intricacies and considerations than I was able to touch on in today’s article.
Until next time,
Andy De Santis RD MPH
PS: If you want to read the piece I wrote on the keto diet last year, you can do so by clicking here.