Metabolism and Bariatric Surgery Study

Weight loss (WL) improves obesity-related co-morbidities such as type 2 diabetes mellitus
(DM). Unfortunately, WL through life-style interventions has a high degree of recidivism and
the paucity of safe, effective and affordable pharmacotherapy together with an increase in
the prevalence of morbid obesity has led to a rise in bariatric procedures. Clinical trials
in patients with DM show that improvements in glycemia vary between procedures and occur in
the following order: Roux-en-Y gastric bypass (RYGB) > sleeve gastrectomy (SG) > laparoscopic
adjustable gastric banding (LAGB) > medical/life-style therapy. This order mirrors the amount
of WL with each intervention and is a major driver of glycemic improvement. The investigators
have shown profound changes unique to RYGB and SG in levels of hormones that make up the
"gut-brain" and "enteroinsular" axes. The association of some of these hormones with insulin
sensitivity (IS) and glycemia independent of WL strongly suggests that glycemic improvements
after surgery occur in part through pathways that are distinct from just calorie restriction.
This study builds on results showing that levels of fibroblast growth factor 19 (FGF19), a
protein secreted by intestinal cells, are increased after RYGB and SG but not after low
calorie diet (LCD). This difference may affect hormones that control the stress response to
weight loss. The investigators will explore differences in hormones of the gut that affect
appetite, body weight, and stress response in healthy lean and obese individuals. Obese
individuals will also be studied before and after 15% body weight loss induced by LCD, RYGB
or SG, and again at 1 year after study enrollment.

Inclusion Criteria:

Men and women Ages 18-65 Years Old

Exclusion Criteria:

1. Altered Sleep-wake Cycle

2. Type 1 or 2 diabetes

3. Previous Bariatric Surgery

4. Lactose Intolerance

5. Any Special Diet restrictions.

6. Use of medications that may affect body weight at screening or during a 3 month period
prior.

7. Untreated thyroid disease

8. Other medical conditions like Cushing's, acromegaly, Hearth failure, Crohn's disease,
etc

9. Pregnancy

10. Tobacco or opioid use

11. Alcohol dependence

12. > 3% weight change over the 3month period prior to screening

13. Unwillingness to maintain current level of physical activity over duration of study
period