As a foreword, this is not a bash on Ketogenic diets by any means. Some research has shown practical use in specific populations. This post is to educate and debunk the misinterpretation of the ketogenic diet for body composition purposes.
The Ketogenic Diet seems to have become the next best thing since the era of eliminating all fat in a way to combat fat gain and enhance body composition. Several bodybuilders, physique athletes and fitness gurus claim that Keto is the be all and end all for fat loss. After being brainwashed myself about a year ago, Ive finally come to my senses and decided to look into the topic in more depth. This blog will attempt to shed some light on what the Ketogenic diet is and how some of the research has been misinterpreted.
I think it would be appropriate to start this post with introducing the Ketogenic Diet. In its raw form the diet typically consists of a consumption of fat around 70%, carbohydrate near 5% and protein to 20%. As you can infer, this diet is essentially the exact opposite of the fat elimination diet of the 90’s. The prefix of ketogenic is keto, short form for ketone and the suffix being genic, meaning creating. So Ketogenic literally means keto creating or producing. Ketones are actually another source of fuel in the body that are created from fat when carbohydrate availability is low as
showcased in a Ketogenic Diet. When carbohydrate stores become low, fat cells are targeted for their abundance of energy where the liver then converts stored triglycerides to ketones and free fatty acids. When carbohydrate is this low, the brain cells and other tissues begin to suffer as glucose is their preferred source of fuel. Because the body is extremely adaptable, ketones are created in order to fuel these tissues. Over a period of carbohydrate reduction, the body will eventually enter ketosis where ketone’s become an alternative source of fuel.
So now that we have covered what the diet is and how it changes our physiology, lets look at it from a body composition standpoint. If the body enters “ketosis” and ketosis results in ketones for energy and ketones are derived from targeted fat cells then that would mean we would mobilize more fat and improve body composition, right?! On the surface this seems very logical, eat more fat, use more fat as fuel and voila you will lose fat. Who doesn’t want to lose a little more fat? The problem is that its not that simple. This is where the research has been misinterpreted and why the Ketogenic diet is arguably no better than any other diet.
Multiple studies on do show reductions in weight. The mechanisms have been discussed over the past few years for why this is the case. Initially, the drastic reduction in carbohydrate will result in weight loss from 5-7 pounds over a week or so as every gram of glycogen (stored sugar) results in the retention of 3-4 grams of water. Therefore if you deplete glycogen stores via reduction in carbohydrate intake you will also decrease intracellular water retention resulting in weight loss. In a review by Paoli et al (2013) one of the main findings was that the Ketogenic diet typically results in a higher satiety due to the increased intake of fat and protein. Foods higher in fat and protein tend to be more satiating than carbohydrates rich options. Looking at a typical North American (NA) diet, most carbohydrates that are consumed are highly processed and contain little fiber meaning that you will be less likely to overeat on the ketogenic diet. This is a great benefit but is not indicative of greater FAT loss or a “metabolic advantage”. So practically if we compare a keto diet to a normal NA Diet, the keto group would be less hungry and eat less resulting in a caloric deficit. They also ate more protein, and protein has the highest thermogenic effect of all macronutrients. In fact approximately 30% of calories derived from protein are eliminated as heat. To keep it simple, if you eat 100 calories of protein, nearly 30 calories will be expelled as heat and not metabolized for tissue repair and other functions. To make this simple, The keto group will typically lose more weight not because of a metabolic advantage shifted towards fat mobilization, rather it results in less total calories consumed as 30% of the protein calories are oxidized as heat. If you eat less calories and increase thermogenesis through higher protein consumption, you will lose weight. Can you imagine?
Finally to drive this point home, a study by Johnston et al (2007) took a ketogenic diet (60% fat, 5% Carbs) and and a non ketogenic low carb diet (30% fat, 40% carbs) and matched protein consumption in both groups. The overwhelming finding was that both diets were equally effective for weight loss. So if you take anything from this post, understand that the ketogenic diet does work BUT is no more effective than any other diet assuming protein is matched.
Im going to leave you with some Pros and Cons of Ketogenic dieting. Remember, Its not to say that ketogenic diets are bad and you should never consider it. I would disagree with that statement, but it is important to consider the reasoning for why you are doing it and whether that reasoning is built on bedrock or sand.
- Research has shown that those with cancerous tumors, type 2 diabetes or seizures can improve quality of life and remission through reduction in carbohydrate intake following a ketogenic diet.
- It is possible to create a caloric deficit with a ketogenic diet which would result in weight loss over time.
- Some research suggests that for some people there may be a mental enhancement when following a ketogenic diet.
- No more effective than any other diet when protein is matched.
- Drastically reducing carbohydrate intake can have adverse side effects (renal damage, hypoglycemia, vitamin and mineral deficiencies).
- Reduction in Carbohydrate impedes anaerobic metabolism –> important for sport performance.
- Could be hard to adhere to as the diet may be to restrictive.
Harmon, A. (2017). Ketogenic diet. Salem Press Encyclopedia Of Health,
Johnston CS, Tjonn SL, Swan PD, White A, Hutchins H, Sears B. Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets. Am J Clin Nutr 2006;83:1055– 61.
Paoli, A., Rubini, A., Volek, J. S., & Grimaldi, K. A. (2013). Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal Of Clinical Nutrition, 67(8), 789-796. doi:10.1038/ejcn.2013.116