Report Title

The Effectiveness of a Preoperative Lifestyle-Based Weight Loss Program on Postoperative Outcomes in Bariatric Patients: A Secondary Data Analysis

Collective Title

Master of Science in Nutrition and Dietetics Research Reports 2021


Background: Obesity is a multifactorial and largely preventable chronic disease. There are many interventional methods that can be used in treating obesity, such as diet and lifestyle interventions. Surgical intervention is also an effective treatment option that is utilized for those that are severely obese. Bariatric surgery helps to achieve weight loss, as well as reduce the risk and/or manage comorbidities. In the U.S., many insurance companies and certain bariatric centers require patients to lose weight prior to surgery. The explanation for preoperative weight loss stems from its potential correlation with reduction in surgical complications, improved adherence to stringent postoperative nutrition requirements, and increased percent weight loss after surgery.

Objective: To assess the influence of the Loma Linda University Health’s (LLUH) Say No to OverWeight (Say NOW) weight loss program on lifestyle and behavioral changes, participants' self-efficacy, and weight loss both pre- and postoperatively, as well as evaluate the potential correlation between pre- and postoperative weight loss.

Methods: Sixteen subjects (age=45.9 ± 11.5 years; BMI=46.1 ± 8.3 kg/m2) participated in a comprehensive 36-week lifestyle-based program to promote weight loss before and after bariatric surgery. During the preoperative phase, baseline data on anthropometrics, food frequency, meal patterns and timings, miscellaneous lifestyle habits and perceived level of self-efficacy regarding eating behaviors were collected. Participants then underwent a 24-week lifestyle program and at the end of the intervention, the same outcomes were re-assessed before surgery was performed. Following surgery, the subjects completed the same program for 12 weeks, with additional data (as above) being collected at the beginning and at the end of the 12 weeks. Intra- and inter-phase comparative analyses were conducted on anthropometrics (weight, BMI, and waist circumference) using Wilcoxon Signed Ranks Test. Pre- and postoperative survey data was utilized to identify changes in lifestyle habits (food frequency, meal patterns and timings, miscellaneous lifestyle habits, and perceived level of self-efficacy).

Results: There was a statistically significant reduction weight and BMI from Baseline to Pre-Surgery, Post-Surgery to Final, and Baseline to Final (p=0.016, p=0.003, p=0.000 respectively). A reduction in waist circumference was also observed from Post-Surgery to Final and Baseline to Final (p=0.002, P=0.000 respectively). Participants who experienced >3% preoperative EWL exhibited greater %EWL after surgery and participants with a larger waist circumference experienced greater preoperative waist circumference loss. Over the course of the program, there was observable improvement in diet and lifestyle-related factors, as well as overall self-efficacy compared to Baseline.

Conclusion: The present findings indicate that a comprehensive lifestyle-based weight loss program can be beneficial in facilitating further benefits among bariatric patients, particularly regarding anthropometric measurements. Additionally, a program such as this can lead to significant improvements in diet and lifestyle-related factors, as well as perceived self-efficacy regarding eating behaviors.

LLU Discipline

Nutrition and Dietetics


Nutrition and Dietetics

First Advisor

Edward Bitok

Second Advisor

Olivia Moses

Third Advisor

Caitlin Mckee

Fourth Advisor

Lida Gharibvand

Fifth Advisor

Gurinder Bains

Degree Name

Master of Science (MS)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Obesity--United States--Treatment.


Research Report

Page Count

20 p.

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Research Reports

Collection Website


Loma Linda University. University Libraries.