Very low‐calorie ketogenic diets (VLCKDs) are nowadays considered a notable example of a dietary‐based treatment with proven efficacy against a variety of conditions. In particular, VLCKDs have been strongly recommended as a valuable nutritional strategy for the treatment and management of obesity and associated comorbidities, including type 2 diabetes (T2D), dyslipidaemia and insulin resistance. 1, 2 Several review articles and consensus statements on the appropriate application of, and the main indications and contraindications for VLCKDs, have been recently published. 1, 2 These comprehensive discussions outline novel approaches and insights into the mechanisms that can increase the benefits and reduce the potential harmful effects of these diets for patients. In this context, VLCKDs have been included as a therapeutic option for patients with obesity, who failed to lose weight or reached a plateau in weight loss following a conventional dietary approach due to their efficacy in terms of weight loss, visceral fat reduction, improvement of metabolic parameters 1 and inflammatory markers. 3 Overall, VLCKD rapidly fulfils the recommended 5%–10% weight loss within 6 months to produce clinically relevant health benefits. 4 A recent meta‐analysis has also shown that weight loss achieved during the ketogenic phase is stable up to 2 years, with a valuable safety profile and overall rates of discontinuation that are very similar to standard low calorie diets. 4 A loss of 15% or more of body weight is frequently achieved with a VLCKD, and can induce remission of type 2 diabetes (defined as HbA1c plasma levels< 6.5%, persisting for at least 3 months in the absence of pharmacotherapy) in a large proportion of patients. 5, 6 Therefore, in consideration of the rapid and significant weight loss that can be obtained, VLCKD has emerged as a viable option for achieving T2D remission in patients with obesity. 7 A recent systematic review of clinical trials considering diets for remission of diabetes concluded that formula‐based meal replacement was the most effective dietary approach, given that they usually provide less energy than a diet based on standard food. 8 In this context, the clinical efficacy of VLCKD is also related to the use of meal replacement based on protein preparations of high nutritional value. 1 This represents the most promising clinical application of VLCKD in terms of effective cardiovascular protection, given that altered glucose metabolism represents a very frequent finding in patients with coronary artery disease. 9

On the other hand, VLCKDs have recently become popular, well beyond their proven clinical benefits and potential disease modifying effects, and their use has increased a lot in the last years. 3 This observation is largely due to VLCKDs representing a highly effective nutritional approach in patients who require rapid weight loss over a short‐term period, 1, 2 The success of these diets, especially among patients who failed to lose weight following different nutritional protocols, is due to a number of key physiological outcomes including the rapid loss of fat mass, the paucity of side effects, the maintenance of lean body mass and the strong anorexigenic effect, together with the relative simplicity of the protocol. Taken together, these features render VLCKD extremely appealing also for subjects who are not eligible for this nutritional therapy. In this context, it is critical to recall that the use of VLCKD requires a clear clinical indication as well as a strict medical supervision due to the potential harmful effects of this