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

<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 (&lt;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).

***背景：*** 极低碳水化合物生酮饮食（very low-calorie ketogenic diet, VLCKD）近年来被提出作为极具应用前景的肥胖管理营养干预策略。该饮食模式的特征为：每日碳水化合物摄入量低于50克，每千克理想体重摄入1~1.5克蛋白质，每日脂肪摄入量为15~30克，每日总热量约为500~800千卡。
***目的：*** 本文旨在提出一套通用的极低碳水化合物生酮饮食操作规范，并总结现有关于其在体重管理及体重相关合并症方面的疗效，以及潜在不良反应的相关文献。
***方法：*** 本文严格遵循系统评价与Meta分析优先报告条目（Preferred Reporting Items for Systematic Review and Meta-Analyses, PRISMA）指南制定。文献检索、研究筛选、方法学构建及质量评价均由2名研究者独立完成，数据整合采用Meta分析与叙述性合成相结合的方式。
***结果：*** 本次检索共获取645篇文献，其中15项研究符合纳入标准并被纳入分析，最终得到4项核心结论。其一，极低碳水化合物生酮饮食在短期、中期及长期均能显著减轻体重，并改善机体组成参数及血糖、血脂谱。其二，与相同干预时长的其他减重方案相比，极低碳水化合物生酮饮食在降低体重、体脂质量、腰围、总胆固醇及甘油三酯血症方面效果更显著，同时可改善胰岛素抵抗。其三，尽管极低碳水化合物生酮饮食同样能显著降低血糖、糖化血红蛋白（HbA1c）及低密度脂蛋白胆固醇，但上述改善效果与其他减重干预方案相当。其四，在专业医护人员监督下，极低碳水化合物生酮饮食可被视为安全的营养干预手段，因其最常见的不良反应通常临床症状轻微、易于处理，且恢复多为自发性。
***结论：*** 在充分考虑潜在禁忌证并牢记所有膳食干预方案均需个体化的前提下，极低碳水化合物生酮饮食可作为肥胖人群的有效膳食治疗方案。
***PROSPERO注册信息：*** 超重与肥胖人群中极低碳水化合物生酮饮食对体重、机体组成、血糖及血脂参数的疗效评估：一项Meta分析（CRD42020205189）。