Weight Loss on Keto: The Science

5 min read

What is the first thing that you think of when you hear the words "keto diet"? Perhaps, you imagine strict nutrition plans and restricting yourself of foods you enjoy so much? (as you would with any expression containing "diet" in it) Or, in case you have a scientific background, does its ability to treat epilepsy come to mind? Well, most keto enthusiasts have another association- weight loss. Supported by dozens of research outputs, and even more personal accounts of their direct and rapid effects, keto diets have captured the attention of doctors, dietitians, and the general public over the past decade. Today, we will submerge into the mechanisms of keto diets and discuss how exactly they promote weight loss while drawing comparisons to other diets aimed at the same outcome.

Weight Loss in Ketosis

First, we need to understand the process that gives the keto diet its many benefits, and that is none other than ketosis. Ketosis is a metabolic state in which most of the energy our bodies utilize is derived from fat, instead of carbohydrates. Carbohydrates are preferred by the human body as a short-term energy source. This is because they can be carried by blood directly and rapidly utilized by the tissues where they are needed. In this scenario, fat becomes a secondary nutrient as the body takes more time to convert it into readily available energy compared to carbohydrates. However, when we start consuming more fat, it is transformed into ketone bodies which are then used as the primary energy source. But why would anyone want that to happen? To answer this question, we need to consider these macronutrients in terms of their effects on our metabolism: Dietary carbohydrates are stored by our body in the form of glycogen- a chain of adjacent glucose molecules. As more chains are formed, they require 3 grams of water per gram of glycogen to ensure rapid transport through the body and help maintain muscle activity. The following, however, becomes obsolete in ketosis since carbohydrates are no longer the primary energy source. As a result, glycogen is no longer formed, which inevitably reduces the water drawn to it. With it, the total body weight drops too. This usually occurs within the first 10 days from the beginning of a ketogenic diet and is the first indicator of its successful implementation. Approximately 500g of glycogen is stored in the body on a regular diet, indicating the potential loss of 2 kg if it were to be depleted.

What's more intriguing is that weight loss during ketosis is not limited to only glycogen and water. With time, your body adapts its metabolism to increased dietary fat intake, which brings us to the other 2 crucial mechanisms that the keto diet is known for. The first one is the increased use of fat in your body's metabolic processes. The more your body relies on ketone bodies to provide energy, the more it will stimulate their production. Suppose we recall the mechanisms of this process. In that case, it should not come as a surprise that this is manifested by increased burning of fat available in your body, which will be the case for both dietary fat and fat stored in adipose tissue. In other words, your body becomes more efficient in burning fat and prioritises it to other macronutrients, leading to a decrease in the body fat content, and thus, weight. On top of that, ketosis will prevent the production of new adipose tissue, which will also speed up the depletion of existing body fat. Lastly, as the keto diet trains your body to perform lipolysis and burn fat more effectively, this will come in handy when you transition back to a regular diet. Research shows that ketogenic diets can prevent weight gain in the long run due to more optimized and energy-efficient processing of fat.

Ketone Bodies

The second property we are going to talk about has absolutely nothing to do with burning fat, however. What's more fascinating is that researchers consider it to be even more vital to the success of ketogenic diets than the fat-burning mechanism we just discussed. Ready to find out what it is? Ketone bodies have been shown to interact with hormone systems responsible for satiety and appetite. This is all possible thanks to one specific ketone body called beta-hydroxybutyric acid (BHBA). The potential correlation of this molecule with appetite stems from its high concentration in the brain in periods of natural ketosis, such as starvation and lactation. 

Consequently, BHBA was found to act on specific regions of the brain, mainly the hypothalamus, to prolong the time between meals and decrease food intake consistently in animal models. It was only a matter of time until these results were observed in humans, and this is exactly what nutritional science is telling us. A recent study comparing the effects of ketogenic and non-ketogenic nutrients on appetite in starved individuals is an excellent manifestation of this. Despite having equal amounts of calories, the ketogenic drink managed to suppress feelings of hunger for 1.5 hours longer when compared to the carbohydrate-laden one. Interestingly, this was directly correlated with ghrelin- an appetite-stimulating hormone whose levels were significantly lower in people who consumed a ketogenic drink. How does this relate to the keto diet? Given that BHBA is the most common ketone body produced during ketosis, the more you stick to your diet, the more significant the effects of BHBA will be on your appetite and food intake.

Dietary Protein

It is also necessary to be aware of your dietary protein, as it can be both a friend and a foe when it comes to appetite. On the one hand, increasing the protein content of your diet may boost the appetite suppressing effects we just discussed and also aid muscle gain. However, there is a fine line, as excessive protein in your diet will knock you out of ketosis and hamper its benefits. If you want to know how you could increase your protein intake and build muscle without getting out of ketosis, check out our previous article here.

Muscle Gain in Weight Loss

Speaking of muscle gain, sometimes the amount of weight lost on a ketogenic diet may not meet your initial expectations, so we are here to clarify what the reasons for that may be. The first thing to check would be the macronutrients you are consuming. Carbohydrates, and to a lesser extent, protein should be monitored in order to keep you in ketosis, with the former contributing 5-10% of your total food intake, while the latter can vary based on the amount of exercise you are doing, but not exceeding 35%. If these are in order, then it would be sensible to examine the levels of physical activity. Two key takeaways here are the following:

1. As fat is more energy-dense than carbohydrates, you will be consuming more calories with your diet. These will need to be utilized for weight to be lost. 2. Keto diets preserve lean body mass, i.e, muscle mass. Therefore, high amounts of exercise may result in weight gain, however, this will be muscle tissue. A necessary remark on the first point: The ketogenic diet has been shown to increase your basal metabolic rate, meaning that the quality of calories consumed affects the number of calories burned. Thus, your body may require up to 400 additional calories per day to fuel ketosis, gluconeogenesis, and other metabolic functions when on keto.

Final Thoughts:

In conclusion, there is no denying that keto diets lead to weight loss as scientific evidence for that is overwhelming. However, everyone's keto journey will be different. Being equipped with knowledge of why and how it works is crucial for extracting the most out of ketosis and enjoying yourself without worrying about any pitfalls.

References:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3945587/ https://www.sciencedirect.com/science/article/pii/S0195666310000942 https://pubmed.ncbi.nlm.nih.gov/18175736/ https://pubmed.ncbi.nlm.nih.gov/19640952/ https://academic.oup.com/ajcn/article/87/1/44/4633256 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566517/ https://www.medicalnewstoday.com/articles/326484#little-to-no-exercise