Effect of Diet Versus Sleeve Gastrectomy and Gastric Bypass on Appetite

Study Overview
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Brief Summary
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The biggest challenge in obesity management is maintaining weight loss in the long-term. Currently, bariatric surgery is the most effective treatment, leading to sustained weight loss that is not yet achievable with lifestyle intervention (e.g. diet). The reasons behind its success is still not clearly understood, but beneficial changes in the homeostatic and hedonic appetite systems (the two major physiological regulators of appetite), along with the microbiome (known to have a mediatory effect on appetite) have been shown to occur after bariatric surgery. These alterations are in opposition to what is seen after diet-induced weight loss. Today, the component of appetite regulation that drives bariatric surgeys' long-term success is still unknown. By comparing a lifestyle and surgical intervention in parallel, the investigators can observe the impact of a similar magnitude of weight loss on these three domains of appetite regulation simultaneously, thereby illuminating the mechanisms behind bariatric surgerys' success.

Official Title
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Effects of Diet-induced Weight Loss Versus Sleeve Gastrectomy and Gastric Bypass on Homeostatic and Hedonic Appetite Markers and Gut Microbiota

Conditions
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Obesity

Intervention / Treatment
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* Dietary Supplement: VLED group
* Procedure: Sleeve Gastrectomy group
* Procedure: Gastric Bypass group


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: scheduled for bariatric surgery patient in obesity clinic Body mass index (BMI) 35-55 Exclusion Criteria: Currently taking medication known to affect energy metabolism or appetite Current cancer diagnosis Substance abuse Enrolled in another obesity treatment Eating disorders pre-existing endocrine disorders (e.g. diabetes) will not be excluded, but final analysis will controlled for these conditions

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: VLED group<br>Participants will undergo a 10-week VLED. | Dietary Supplement: VLED group<br>* 10-week weight loss period with total meal replacement, consisting of 750 kcal/day. Measurements will be taken at baseline (before diet start), 10 weeks after intervention start (Wk11), and at 1 year.<br>* Other names: very-low-energy-diet;|
| Experimental: Sleeve Gastrectomy group<br>Participants will undergo standard clinical practice prior to surgery. | Dietary Supplement: VLED group<br>* 10-week weight loss period with total meal replacement, consisting of 750 kcal/day. Measurements will be taken at baseline (before diet start), 10 weeks after intervention start (Wk11), and at 1 year.<br>* Other names: very-low-energy-diet;Procedure: Sleeve Gastrectomy group<br>* Standard clinical practice with 2-week diet consisting of 750 kcal/day prior to surgery. The pre- and post-surgical diet of this group will be matched with the VLED group in macro- and micronutrient composition. Measurements will be taken at baseline (before diet start), 10 weeks after intervention start (Wk11), and 1 year after surgery (sleeve gastrectomy)<br>|
| Experimental: Gatric Bypass group<br>Participants will undergo standard clinical practice prior to surgery. | Dietary Supplement: VLED group<br>* 10-week weight loss period with total meal replacement, consisting of 750 kcal/day. Measurements will be taken at baseline (before diet start), 10 weeks after intervention start (Wk11), and at 1 year.<br>* Other names: very-low-energy-diet;Procedure: Gastric Bypass group<br>* Standard clinical practice with 2-week diet consisting of 750 kcal/day prior to surgery. The pre- and post-surgical diet of this group will be matched with the VLED group in macro- and micronutrient composition. Measurements will be taken at baseline (before diet start), 10 weeks after intervention start (Wk11), and 1 year after surgery (gastric bypass)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Postprandial blood plasma concentration of Glucagon-like peptide-1 (GLP-1, satiety hormone) | Blood samples will be collected at fasting, and then every 30 minutes after a standardized test meal up to 150 minutes. A radioimmunoassay method will be used to measure the concentration of total GLP-1. This method measures antigen concentrations by the use of antibodies. | Week 11 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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diet, bariatric surgery, appetite