Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA.
Adv Nutr. 2021 Feb 1;12(1):223-233. doi: 10.1093/advances/nmaa101.
Use of high-fat, ketogenic diets (KDs) to support physical performance has grown in popularity over recent years. While these diets enhance fat and reduce carbohydrate oxidation during exercise, the impact of a KD on physical performance remains controversial. The objective of this work was to assess the effect of KDs on physical performance compared with mixed macronutrient diets [control (CON)]. A systematic review of the literature was conducted using PubMed and Cochrane Library databases. Randomized and nonrandomized studies were included if participants were healthy (free of chronic disease), nonobese [BMI (kg/m2) <30], trained or untrained men or women consuming KD (<50 g carbohydrate/d or serum or whole-blood β-hydroxybutyrate >0.5 mmol/L) compared with CON (fat, 12-38% of total energy intake) diets for ≥14 d, followed by a physical performance test. Seventeen studies (10 parallel, 7 crossover) with 29 performance (13 endurance, 16 power or strength) outcomes were identified. Of the 13 endurance-type performance outcomes, 3 (1 time trial, 2 time-to-exhaustion) reported lower and 10 (4 time trials, 6 time-to-exhaustion) reported no difference in performance between the KD compared with CON. Of the 16 power or strength performance outcomes, 3 (1 power, 2 strength) reported lower, 11 (4 power, 7 strength) no difference, and 2 (power) enhanced performance in the KD compared with the CON. Risk of bias identified some concern of bias primarily due to studies allowing participants to self-select diet intervention groups and the inability to blind participants to the study intervention. Overall, the majority of null results across studies suggest that a KD does not have a positive or negative impact on physical performance compared with a CON diet. However, discordant results between studies may be due to multiple factors, such as the duration consuming study diets, training status, performance test, and sex differences, which will be discussed in this systematic review.
近年来，使用高脂肪、生酮饮食（KDs）来支持身体表现的做法越来越受欢迎。虽然这些饮食在运动过程中增加脂肪氧化并减少碳水化合物氧化，但 KD 对身体表现的影响仍然存在争议。本研究的目的是评估与混合宏量营养素饮食[对照（CON）]相比，KD 对身体表现的影响。通过 PubMed 和 Cochrane 图书馆数据库对文献进行系统评价。如果参与者健康（无慢性疾病）、非肥胖[BMI（kg/m2）<30]、接受过训练或未经训练的男性或女性在摄入 KD（碳水化合物摄入量<50 g/d 或血清或全血 β-羟基丁酸>0.5 mmol/L）与 CON（脂肪，总能量摄入的 12-38%）饮食至少 14 天后进行身体表现测试，则纳入随机和非随机研究。确定了 17 项研究（10 项平行研究，7 项交叉研究），共有 29 项表现（13 项耐力，16 项力量或强度）结果。在 13 项耐力型表现结果中，有 3 项（1 项计时赛，2 项力竭时间）报告 KD 与 CON 相比表现降低，有 10 项（4 项计时赛，6 项力竭时间）报告无差异。在 16 项力量或强度表现结果中，有 3 项（1 项力量，2 项强度）报告 KD 表现降低，有 11 项（4 项力量，7 项强度）报告无差异，有 2 项（力量）报告 KD 与 CON 相比表现增强。风险偏倚发现一些主要由于允许参与者自行选择饮食干预组的研究存在偏倚的担忧，以及无法对参与者进行研究干预的盲法。总体而言，大多数研究的无效结果表明，与 CON 饮食相比，KD 对身体表现没有积极或消极的影响。然而，研究之间的不一致结果可能是由于多种因素造成的，例如消耗研究饮食的时间、训练状态、表现测试和性别差异等，这些将在本系统评价中进行讨论。
