Extended Abstract

Introduction
Multiple non-invasive and invasive treatment methods are available for addressing obesity, the most common metabolic disorder. Metabolic surgery is the frontline treatment for severe obesity because non-surgical interventions typically result in only moderate weight loss. In contrast, surgical methods achieve greater weight reduction and longer-term weight maintenance. Definitions of successful surgery and optimal weight loss after bariatric surgery vary among studies. However, the time to reach maximum weight loss (MWL) is generally reported to be within the first 1 to 2 years post-surgery. Studies show significant variability in the prevalence of weight regain after bariatric surgery. This study aimed to identify factors associated with weight regain following bariatric surgery in obese patients in Gorgan.
Methods
This longitudinal study included 143 obese individuals (125 women and 18 men) with a mean body mass index (BMI) of 45.97±6.61 kg/m², aged 18-68 years, who underwent bariatric surgery during 2013-19.
Inclusion criteria involved undergoing either sleeve gastrectomy or gastric bypass surgery for weight loss. After explaining the study, participants were invited for interviews, examinations, and anthropometric measurements. A demographic information checklist was completed for each participant. Current height, weight, and waist circumference were measured. Surgery type, blood group, pre-surgery weight, and BMI were extracted from patient records. Weight regain was determined based on one of three criteria: regaining more than 25% of maximum weight lost post-surgery (definition 1), regaining more than 10 kg from the minimum post-surgery weight (definition 2), and an increase of more than 5 BMI units from the lowest post-surgery BMI (definition 3).
Results
Among the participants, 127 (88.8%) underwent gastric bypass surgery, and 16 (11.2%) underwent sleeve gastrectomy. The mean pre-surgery weight was 124.81±22.19 kg (range: 85-198 kg), and the mean post-surgery weight was 83.95±16.53 kg (range: 52-150 kg). The mean duration from surgery to study was 48 months (range: 12-72 months). One hundred participants (70%) reached maximum weight loss within the first year post-surgery. The mean maximum weight loss post-surgery was 48.22±15.44 kg. Weight regain (1-56 kg) was reported in 79.7% of participants, with an average regain of 20.92% (range: 0.44-100%) of the maximum weight lost. Weight regain, based on the three definitions, was observed in 47 participants (33%). In 85% of these individuals, weight regain began in the second or third-year post-surgery, with a mean regain of 17.8 kg (range: 9-40 kg). Twenty-five individuals (17.5%) did not experience any weight regain.
There was no statistically significant difference in the mean duration post-surgery between the weight regain and non-regain groups. According to definition 1, the odds of weight regain were 4.08 times higher in individuals with a BMI of 50 kg/m² or greater compared to those with a BMI less than 50 kg/m². According to definition 2, this odds ratio was 2.69. The prevalence of weight regain based on definitions 1, 2, and 3 was 26.6%, 29.4%, and 18.2%, respectively. A statistically significant association was found between weight regain and gender (P<0.002), with men being 5.14 times more likely to regain weight than women. There was no statistically significant association between pre-surgery BMI and weight regain. Still, a significant relationship was found when categorizing participants by pre-surgery BMI (less than 50 and 50 or greater) and considering the different definitions of weight regain. The odds of weight regain, based on definition 2, were 2.69 times higher in individuals with a pre-surgery BMI of 50 or greater compared to those with a BMI less than 50. According to definition 3, the odds were 4.08 times higher in individuals with a pre-surgery BMI of 50 or greater.
A significant direct relationship was observed between the mean maximum weight loss and weight regain (P<0.047), indicating that individuals with weight regain experienced greater mean weight loss post-surgery compared to those without weight regain. Although weight regain decreased with increasing age, this relationship was not statistically significant. No significant association was found between weight regain and age, education level, marital status, or blood type.
The prevalence of abdominal obesity was 82.2% in women and 50% in men who did not experience weight regain. forty-four (93.6%) of individuals with weight regain had abdominal obesity.
Conclusion
According to the results of the present study, 79.7% of individuals, on average 48 months post-bariatric surgery, experienced some degree of weight regain. The clinically significant prevalence of weight regain varied according to the different definitions used. Overall, the prevalence of weight regain was 33% based on the three definitions, with the highest prevalence (29.4%) observed using definition 2 (regaining more than 10 kg from the minimum post-surgery weight) and the lowest (18.2%) using definition 3 (an increase of more than 5 BMI units from the lowest post-surgery BMI). The time elapsed post-surgery is a critical factor influencing weight regain after bariatric surgery, which could explain the differences in prevalence reported in various studies. In our study, weight regain began in the second and third years post-surgery.
Individuals who achieved greater MWL post-surgery had a higher likelihood of weight regain. The prevalence of abdominal obesity was 93.6% among those with weight regain. Even those who did not experience weight regain, 82.2% of women and 50% of men had abdominal obesity, indicating that surgery alone, without appropriate diet and physical activity, cannot be considered a definitive treatment for obesity and related metabolic disorders, including abdominal obesity.
Ethical Statement
The present study was approved by the Research Ethics Committees of Golestan University of Medical Sciences (IR.GOUMS.REC.1400.254).
Funding
This article is based on Ahmad Masoumi's thesis for obtaining a specialty in internal medicine from the Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran.
Conflicts of Interest
The authors have no conflicts of interest.
Acknowledgement
We are grateful to all study participants and the Research and Technology Vice-Chancellor of Golestan University of Medical Sciences for their financial and moral support.

Key Message
Bariatric surgeries are not a definitive treatment for obesity, as weight loss tends to be regained over time, especially in individuals with higher pre-surgery BMI or those who experienced greater weight loss post-surgery. Men are more likely than women to regain weight.