Evaluating the safety and efficacy of very low calorie ketogenic diets

Despite significant advances in the understanding of obesity and the mechanisms behind it, current interventions are not very successful in the long term. As most of the common obesity-associated diseases arise from excess energy intake relative to energy needs, very low calorie diets (VLCD) characterized by less than 800 kcal per day have shown to promote rapid weight loss and substantially improve^[1] conditions like type 2 diabetes. Although they are intended to be used for only a short period of time, the beneficial effects of following a VLCD are difficult to maintain in the long term, and can be hard to implement in the real world due to the very restrictive nature of the diet.

An alternative to the traditional VLCD involves the use of an initial phase of ketogenic dieting (VLCKD) in which people follow a VLCD, but also restrict the intake of carbohydrates to less than 30 to 50 grams per day. Afterward, both calories and carbohydrates are gradually increased, as outlined in Figure 1. It has been suggested^[2] that the ketogenic dieting phase aids in compliance with the diet due to the appetite suppressant effects of ketone bodies, by promoting weight and fat loss, and the sparing^[3] of lean mass.

The term “ketogenic diet” is widely used in the literature to refer to diets that promote ketosis. However, these diets can vary in their calorie restriction and the percentage of dietary fat and protein they contain. Thus, the authors of the study under review attempted to determine the effects of specifically VLCKD (carbohydrate restricted, ketone-inducing VLCD) on bodyweight and related clinical parameters, as well as its safety.

Very low calorie diets (VLCD) can cause weight loss and improve metabolic health in people with obesity. However, they can be difficult to implement and adhere to. An alternative to traditional VLCD is using an initial ketogenic phase in which carbohydrates are also restricted in order to control hunger and adherence to the diet (VLCKD). As the term “ketogenic diet” is used in the literature for ketogenic diets with different amounts of calories and percentages of dietary fat and protein, the authors wanted to determine the effects of specifically VLCKD (carbohydrate restricted VLCD) on weight loss and related clinical parameters.