Effect of Diet Versus Sleeve Gastrectomy and Gastric Bypass on Appetite

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

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.

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