Gastric bypass surgery 

Gastric bypass surgery is a proven surgical weight loss procedure that has been performed in various forms for over 40 years. David Thoman, MD, FACS, offers the most popular variation, Roux-en-Y gastric bypass bariatric surgery. One of the few surgeons in Central and Southern California employing the minimally invasive SILS technique, Dr. Thoman specializes in gastric bypass surgery for patients from Santa Barbara, San Luis Obispo, Fresno, Bakersfield and Los Angeles, California.

Understanding gastric bypass surgery


Like all metabolic procedures for weight loss, Gastric Bypass works by altering the hormones in your gastrointestinal tract causing your body’s set point for weight to lower.  Your body then creates weight loss by taking away your appetite and speeding up your metabolic rate until you are at your new lower weight.

Dr. Thoman performs gastric bypass surgery laparoscopically, which enables him to perform the procedure by inserting a small video camera and surgical instruments through small incisions in the abdomen, instead of one large incision (used in traditional “open” surgery).


Throughout the country, including Fresno, Bakersfield, and Ventura, Roux-en-Y gastric bypass surgery is currently the most popular weight loss surgery procedure. The advantages of laparoscopic Roux-en-Y surgery include:

  • Slightly higher weight loss then gastric sleeve.

  • Higher cure of diabetes in certain patient groups then gastric sleeve.

  • Over 90% cure rate of gastroesophageal reflux, whereas the gastric sleeve can sometimes make it worse.


Gastric bypass surgery is so effective that weight loss begins immediately after the surgery and usually continues for approximately 12 to 18 months. Your rate of weight loss will depend on your height and weight prior to surgery, as well as your diet, level of exercise, and daily calorie requirements. You can expect to lose about 70-80% of your excess body weight within 18 months of surgery.

Our patients are consistently thrilled with the significant weight loss they are able to achieve. Surgery can improve the health, self-esteem, and quality of life of many of the women and men who have chosen our practice.


During your consultation, Dr. Thoman will thoroughly review your health history and discuss the risks and complications associated with gastric bypass surgery, including:

  • Pulmonary embolism: A potentially fatal blood clot in the lung

  • Intestinal leak: Leakage of bowel contents resulting from improper healing.  Dr. Thoman sews all connections by hand and has never had an intestinal leak in thousands of procedures.

  • Stomal stenosis: Narrowing of the connection between the stomach and intestine requiring an endoscopy

  • Internal hernia: Intestine becomes caught in an internal defect (usually after 100 pounds is lost)

  • Marginal ulcer: Erosion of the lining of the intestine (usually treated with an antacid)

  • Iron, calcium, and vitamin deficiencies: Avoided by following the prescribed postoperative vitamin regimen.