Ketogenic Diet: To be, or not to be?

Written by: Ying-Xian Goh1, Xin Yi Quek2, and Noraidatulakma Abdullah (Ph.D.)1
Published date: 01 March 2021

1 UKM Medical Molecular Biology Institute (UMBI), UKM Medical Centre, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.
2 Nutrition with Wellness Undergraduate Program, Faculty of Applied Sciences, UCSI University, Kuala Lumpur, Malaysia.

An example of ketogenic diet. Photo courtesy: Boontoom Sae-Kor/ Shutterstock

The global rise of awareness on overweight and obesity recently has enhanced the search for an efficient weight-loss diet. Although many types of diet are available, ketogenic diet (keto-diet) (also known as low carbohydrate-high fat, LCHF diet) has garnered much popularity for its effectiveness and benefits in weight loss. In July 2019, Insight Partners, a global private equity and venture capital firm, has reported that the global ketogenic diet market accounted to 9.7 billion USD and will grow annually at the rate of 5.5%, reaching 15.64 billion USD by 2027 [1]. Ketogenic diet is introduced in the 1920s as a treatment for epilepsy, especially for serious childhood epilepsy, and since the 1960s, ketogenic diet has become the most common method of weight management [14]. However, ketogenic diet was considered as a kind of diet faddism, and its long-term impact on human health remained inconclusive.

Ketogenic diet involves ketosis, a metabolic process in which our body uses fat and ketones rather than glucose as its main fuel source to generate energy, due to the restricted carbohydrate supply from the diet. The diet relatively increases the consumption of fatty meat, butter, and other high-fat dairy products. In addition, this diet only allows carbohydrate intake that less than 50 grams a day, and it can be as low as 20 grams per day. Since ketogenic diet is restricting carbohydrate intake, consumption of fruits, legumes (like beans and lentils), most dairy, starchy vegetables, and whole grains are not advisable. This “expensive” metabolic process uses up more energy compared to normal metabolic processes and hence, increases weight loss. Besides, keto-diet contributed to weight loss by affecting both body fat and lean mass. An 8-weeks-long study concluded that ketogenic diet can decrease body fat mass and visceral adipose tissue without decreasing lean body mass [2]. However, keto-diet might not be useful to increase the muscle mass [2] and might deteriorate it over a prolonged period [3].

The mechanisms on how the diet causes weight-loss are not clearly established until today. Some research believes that the main reasons that caused the weight-loss were the reduced calorie intake and increased satiety (feeling of being full) effect of ketogenic diet instead of the composition of the diet itself [4,5]. Moreover, a study also hypothesized that keto-diet will reduce the appetite because the lower levels of appetite-stimulating hormones such as leptin, insulin, and ghrelin was observed under carbohydrate restriction [4].

Ketogenic diet has significantly reduced the total cholesterol [6], increased in “good” (high-density lipoprotein, HDL) cholesterol [6–10], as well as reductions in both “bad” (low-density lipoprotein, LDL) cholesterol [6] and triglycerides levels [6,8,9]. These results were observed not only in obese participants with the risk factors of metabolic syndrome [6], but also in normal-weight participants [10]. Another study reported that ketogenic diet that high in unsaturated fatty acids and low in both carbohydrates and saturated fatty acids enhances the performance of triglycerides and HDL (good) cholesterol in the diabetic population [11]. Thus, ketogenic diet is also believed to reduce cardiovascular risk by decreasing atherogenicity [7]. LDL (bad) cholesterol also can be reduced by consuming a medium-carbohydrate high-protein (MCHP) diet, and not necessarily an LCHF diet [12]. Hence, it is deduced that, apart from low carbohydrate content, the type of fat (saturated or unsaturated) also plays a vital role in ketogenic diet towards the overall wellbeing. However, there are also contradicting findings reported that there are no significant difference in both total and LDL (bad) cholesterol levels after 12 months of ketogenic diet compared to a conventional diet, except at the initial 3 months of the diet, where “bad” cholesterol levels were lower in conventional diet group [13].

In terms of the population with comorbidities, such as obesity and diabetes, ketogenic diet has been proven to improve their diabetic conditions [5], such as better plasma glucose level (improve as much as 75%), and glycated hemoglobin A1c (HbA1c) measurement [14]. Dashti and colleagues also observed a significant drop in cholesterol levels (both total and LDL) after a week of practicing ketogenic diet among obese diabetic patients [15].

Despite its benefits, ketogenic diet will also cause short- and long-term side effects. One of the most common short-term side effects is dehydration, which symptoms include dry mouth, headache, dizziness, and blurred vision [16]. Besides, ketogenic diet will cause fatigue because our body is experiencing ketosis, the process of burning fats instead of carbohydrates, to produce energy for our daily activities [16]. Bad breath (halitosis) might happens too, but it can be eased with sugar-free mints [16]. If one practices a prolonged (several years) ketogenic diet, hypocalcemia (low in calcium content) might happens as the diet promotes intermittent acidosis, hence increasing bone resorption (breakdown) and urinary calcium excretion [17]; resulting in lower bone mineral content and bone density of an individual [16].

In a nutshell, ketogenic diet could be an interesting way to treat certain conditions and may promote weight loss. However, it not really sustainable for one to practice it as the diet rely on a large portion of red meat and fats which could be unhealthy. Furthermore, the inconsistency of practicing ketogenic diet might lead to a “yo-yo diet” and weight fluctuation that is closely associated with increased mortality. The available studies on ketogenic diet are normally limited in observational time or small study samples which might imply sample bias. Hence, the long-term effect of practicing ketogenic diet towards overall wellbeing still warrants further research. Last but not least, it is advised to consult a professional physician or a registered dietitian if you wanted to embark on a diet with unknown future impact.

 

Reference

  1. The Insight Partners. Ketogenic Diet Market to 2027 – Global Analysis and Forecasts By Product Type (Supplements, Beverages, Snacks, Dairy, and Others); Distribution Channel (Hypermarket & Supermarket, Specialty Stores, Convenience Stores, and Others); and Geography. Mark Res Rep. 2019. doi:TIPRE00006281
  2. Vargas S, Romance R, Petro JL, Bonilla DA, Galancho I, Espinar S, et al. Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial. J Int Soc Sports Nutr. 2018;15: 31. doi:10.1186/s12970-018-0236-9
  3. Kephart W, Pledge C, Roberson P, Mumford P, Romero M, Mobley C, et al. The Three-Month Effects of a Ketogenic Diet on Body Composition, Blood Parameters, and Performance Metrics in CrossFit Trainees: A Pilot Study. Sports. 2018;6: 1. doi:10.3390/sports6010001
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