Very Low-Carbohydrate Ketogenic Diet Before Bariatric Surgery: Prospective Evaluation of a Sequential Diet

Abstract

OPOD, including 10 days of a VLCKD, was safe and effective in morbidly obese patients, and it seems to be promising in morbidly obese patients with and without T2DM scheduled for laparoscopic bariatric surgery.

Effectiveness and Characterization of Severely Energy-Restricted Diets in People with Class III Obesity: Systematic Review and Meta-Analysis

“…Four publications contained more than one intervention arm [58][59][60][61], and all intervention arms were eligible for inclusion as separate comparison arms. Due to the limited number of publications found reporting long-term dietary interventions, comparison arms from each publication were separated and categorised based on the dietary intervention durations of 4 weeks and ≥6 weeks.…”

“…Pooled results were calculated using the weighted mean difference in kg, with a 95% confidence interval (CI). In one publication that did not report mean weight loss [61], mean end weight was subtracted from mean baseline weight, and a standard deviation of the change in weight was calculated using the reported p-value for the mean change in weight, because the result for a Student's t-test was quoted in that publication. The t-value was obtained from a Student's t distribution table, and the sample size (n) was then used to calculate the degrees of freedom (df, where df = n−1).…”

“…The correlation coefficient was calculated from the only publication included in the meta-analysis [61] that reported the standard deviation of baseline and end weight mean, and in which the standard deviation for change in weight could be calculated using the reported p-value.…”

“…Full texts of these 157 publications were accessed and screened, resulting in 146 publications being excluded (see Figure 1 for details). Eleven publications met our selection criteria [58][59][60][61]64,[68][69][70][71][72][73], of which ten publications-which included 15 comparison arms-were able to be used in our meta-analyses [58][59][60][61]64,[68][69][70][71][72]. One publication [73], which was included in the systematic review, had to be excluded from the meta-analyses as it did not report weight in absolute terms nor provide a final measurement for average weight, from which weight loss could be calculated.…”

“…In four publications (four comparison arms) [64,68,70,71], only participants who had successfully completed a TMR diet program and had lost a targeted amount of weight were selected, resulting in artificially high participant diet completion rates (83 to 100%). Ten publications used non-randomised methods for participant allocation into intervention arms [58][59][60][61]64,[68][69][70][71]73], and in six of these the classification of the intervention status was potentially affected by knowledge of the outcome by the investigators, as the intervention status was unclear at baseline, classified retrospectively, or prior to the point of delivery of the intervention [59,61,64,68,70,71].…”