title: Clinical impact of a 6-week preoperative very low calorie diet on body weight and liver size in morbidly obese patients.
abstract: BACKGROUND
  Laparoscopic Roux-en-Y gastric bypass (LRYGB) may be a technically challenging surgical technique when features such as thick abdominal wall and increased liver volume are present. Very low calorie diets in the form of liquid meal replacements given 6 weeks prior to surgery have proven to decrease liver volume. The aim of our study was to assess the effect of a 6-week preoperative low calorie/regular diet on liver volume and body weight in morbidly obese patients.
  
  
  METHODS
  A pilot study was carried out in 20 morbidly obese patients with an 800-kcal diet for 6 weeks. They were followed weekly to ensure proper compliance. CT scan was used for determining liver volume every 2 weeks in order to assess the impact of the diet. Baseline values were taken as controls for every patient as tied measures. Statistical analysis was suitable to variable scaling and performed using SPSS v. 20.0. Parametric and non-parametric test for tied measures were done. Any p value lesser than 0.05 or 5% was considered as statistically significant.
  
  
  RESULTS
  Twenty patients adhered to the diet intervention for 6 weeks prior to LRYGB. Median ± SD age was 34.5 ± 11.5 years and 17 were female (85%). Heart rate and blood pressure did not vary across the study. Initial median ± SD BMI was 46.02 ± 5.29 kg/m2 (range 38.7-54.8). Repeated and tied measurements across the 6 weeks of treatment within individuals resulted statistically significant for reducing BMI (p < 0.0001). CT scan assessed liver volume initially as a control and in weeks 2, 4 and 6. Parametric and non-parametric assessment for multiple measurements also showed statistical significance among these values (p < 0.0001). Diet tolerability was additionally evaluated with a questionnaire showing more than 80% of acceptability with discrete rates of nausea (15%) and diarrhoea (15%).
  
  
  CONCLUSIONS
  Based on our results, we demonstrated that a very low calorie diet with home ingredients is capable for effectively reducing body weight and liver size in morbidly obese patients. This relatively short intervention (4 to 6 weeks) was accomplished in all our patients with a high frequency of compliance and a low rate of secondary effects.
authors.affiliation: Department of Surgery, Instituto Nacional de la Nutrición Salvador Zubirán, Vasco de Quiroga 15, 14000, Mexico City, Mexico.
authors.forename: Jordán
authors.initials: J
authors.lastname: González-Pérez
authors.forename: Sofía
authors.initials: S
authors.lastname: Sánchez-Leenheer
authors.forename: Alfredo Rivas
authors.initials: AR
authors.lastname: Delgado
authors.forename: Lizbeth
authors.initials: L
authors.lastname: González-Vargas
authors.forename: Mariana
authors.initials: M
authors.lastname: Díaz-Zamudio
authors.forename: Gerardo
authors.initials: G
authors.lastname: Montejo
authors.forename: Sergio
authors.initials: S
authors.lastname: Criales
authors.forename: Nicholas
authors.initials: N
authors.lastname: Williams
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Pantoja
authors.forename: Mauricio
authors.initials: M
authors.lastname: Sierra
authors.forename: David
authors.initials: D
authors.lastname: Velázquez-Fernández
authors.forename: Miguel F
authors.initials: MF
authors.lastname: Herrera
mesh_terms: D000293:Adolescent; D000328:Adult; D001835:Body Weight; D031204:Caloric Restriction; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D010535:Laparoscopy; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D009767:Obesity, Morbid / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D010349:Patient Compliance; D018579:Patient Selection; D010865:Pilot Projects; D057234:Preoperative Period; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D015431:Weight Loss