European Guidelines for Obesity Management in Adults with a Very Low-Calorie Ketogenic Diet: A Systematic Review and Meta-Analysis

Abstract

<b><i>Background:</i></b> The very low-calorie ketogenic diet (VLCKD) has been recently proposed as an appealing nutritional strategy for obesity management. The VLCKD is characterized by a low carbohydrate content (<50 g/day), 1–1.5 g of protein/kg of ideal body weight, 15–30 g of fat/day, and a daily intake of about 500–800 calories. <b><i>Objectives:</i></b> The aim of the current document is to suggest a common protocol for VLCKD and to summarize the existing literature on its efficacy in weight management and weight-related comorbidities, as well as the possible side effects. <b><i>Methods:</i></b> This document has been prepared in adherence with Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Literature searches, study selection, methodology development, and quality appraisal were performed independently by 2 authors and the data were collated by means of a meta-analysis and narrative synthesis. <b><i>Results:</i></b> Of the 645 articles retrieved, 15 studies met the inclusion criteria and were reviewed, revealing 4 main findings. First, the VLCKD was shown to result in a significant weight loss in the short, intermediate, and long terms and improvement in body composition parameters as well as glycemic and lipid profiles. Second, when compared with other weight loss interventions of the same duration, the VLCKD showed a major effect on reduction of body weight, fat mass, waist circumference, total cholesterol and triglyceridemia as well as improved insulin resistance. Third, although the VLCKD also resulted in a significant reduction of glycemia, HbA1c, and LDL cholesterol, these changes were similar to those obtained with other weight loss interventions. Finally, the VLCKD can be considered a safe nutritional approach under a health professional’s supervision since the most common side effects are usually clinically mild and easily to manage and recovery is often spontaneous. <b><i>Conclusions:</i></b> The VLCKD can be recommended as an effective dietary treatment for individuals with obesity after considering potential contra-indications and keeping in mind that any dietary treatment has to be personalized. <b><i>Prospero Registry:</i></b> The assessment of the efficacy of VLCKD on body weight, body composition, glycemic and lipid parameters in overweight and obese subjects: a meta-analysis (CRD42020205189).

Metabolic Derangement in Pediatric Patient with Obesity: The Role of Ketogenic Diet as Therapeutic Tool

“…Indications and contraindications for the use of VLCKD diets in adults, are shown in Table 3 [187,188]. VLCD and VLCKD diets are administered orally and often using commercial products that contain nutrients of high biological value, and may be in solid, liquid, or powder form.…”

“…In addition, VLCKDs can be followed for 12 consecutive weeks, under medical supervision [189]. [187]. BMI = body mass index; NAFLD = nonalcoholic fatty liver disease; PCOS = polycystic ovarian syndrome; SGLT2 = sodium-glucose cotransporter 2.…”

“…Finally, no clinically relevant changes in liver function have been reported during VLCKD, and this diet can be considered safe [ 193 ]. The most frequently reported side effects are headache, halitosis, constipation, alternating with diarrhea, electrolyte disorders, and muscle cramp [ 187 ].…”

“…Moreover, a recent systematic review and meta-analysis of 15 studies (7 noncontrolled, 2 controlled, and 6 randomized controlled studies) shows significant reduction in body weight and BMI at 1, 2, 4–6, 12, and 24 months, and this and appears to be associated with larger weight loss rates compared to other diets with a different energy content (i.e., LCD and VLCD) of the same duration [ 187 ]. They also found a reduction in waist circumference and a loss of lean mass, comparable to that found in subjects who follow other dietetic interventions [ 187 ].…”

“…However, the poor adherence to this type of treatment raises the question of what other dietary interventions can be effectively applied in children with obesity and metabolic derangement. Although the evidence reported in this review makes it clear that the use of the KD in adult patients with obesity, metabolic syndrome, and T2DM, is now routine, with positive effects in reducing metabolic disorders [ 187 ], few studies were found to be conducted on children on this topic in the literature [ 220 , 221 , 222 , 226 ]. The reasons limiting this type of study are both the difficulty to apply this type of diet in a child’s daily life (lack of acceptance of certain foods, poor palatability, meals outside the home to be managed by parents), which would lead to scarce compliance in the long term, with consequences on the child’s social sphere, but also the impact of the cost of the diet on the family.…”