Our Orange County Bariatric Surgeon and Staff

David Oliak, M.D.

Medical Director
Dr. Oliak is a board certified, fellowship trained General Surgeon who specializes in laparoscopic weight loss surgery (Laparoscopic Adjustable Gastric Banding and Laparoscopic Gastric Bypass) in Los Angeles and Orange County, California.

Dr. Oliak received his medical degree from Washington University in St. Louis, Missouri, and completed his General Surgery residency at Harbor-UCLA Medical Center in Los Angeles, California. Following residency training, Dr. Oliak moved to the East Coast for a one year fellowship in laparoscopic and bariatric surgery at Hackensack University Medical Center in New Jersey.

Following fellowship training, Dr. Oliak went into practice as a laparoscopic weight loss surgeon in Los Angeles and Orange County, California. Dr. Oliak's goal has always been to provide great long-term outcomes for his patients. He achieves this goal by providing excellent surgery and focusing on patient education and postoperative support. He has performed more than 1400 laparoscopic bariatric operations since his fellowship and has achieved excellent weight loss outcomes with complication rates that are lower than the published benchmarks. Dr. Oliak publishes his Gastric Bypass outcomes and his Gastric Banding outcomes on this website.

Dr. Oliak is regarded as an expert in the field of laparoscopic weight loss surgery. He has appeared on national television shows, including The View (see clip) and The Tyra Banks Show (see clip), to discuss laparoscopic weight loss surgery. He has completed numerous research studies pertaining to laparoscopic weight loss surgery, including studies on the learning curve and studies on surgery for heavier patients. He has published his research in numerous scientific journals and has presented his data at national and international surgical meetings (see Curriculum Vitae below for details).

See Dr. Oliak's Curriculum Vitae

Allison Merriman, MMSc., PA-C

Physician Assistant
Allison is a board certified physician assistant who completed her medical education and training at Yale University School of Medicine in New Haven, Connecticut. She has been in practice since 2002. Allison also holds a bachelors degree in exercise science from Western Washington University. She has been involved in weight management for many years and was an instructor for a childhood obesity clinic, educating children regarding obesity and disease prevention. Allison has completed and published research in the field of bariatrics and is an active member of the American Society for Metabolic and Bariatric Surgery.

Jody Jensen, MS, PA-C

Physician Assistant
Jody received her Bachelor's degree in Nutrition from Cal Poly San Luis Obispo and went on to get her Master's degree in medicine from Western University of Health Sciences. She is a board certified physician assistant and a member of the American Society for Metabolic and Bariatric Surgery. She enjoys an active lifestyle, competing in marathons and triathlons, traveling, and takes a special interest in nutrition.

Jennifer

Practice Manager
Jennifer is a certified public accountant and the practice manager. She holds a Bachelors of Science degree in business management and accounting from the University of Maryland. She has over seven years of experience at Arthur Anderson LLC as a senior auditor and at Ernst & Young Corporate Finance LLC as a vice president in corporate restructuring. Jennifer ensures that Dr. Oliak's practice runs smoothly and that patients receive outstanding customer service.

Melanie

Patient Coordinator
Melanie obtained her Bachelors of Science degree in biological sciences from the University of California, Irvine. She has been in the medical field since 2005 and has extensive knowledge regarding insurance approvals and protocols. She is always willing to answer your questions as she guides you through the entire process to surgery. Melanie is passionate about health and nutrition and is continuing her education in this field. She currently hosts her healthy cooking class as part of our existing program.

Marlena

Surgical Coordinator
Marlena is the weight loss surgery coordinator for Chapman Medical Center. For patients having surgery at Chapman, Marlena will schedule preoperative office appointments, coordinate preoperative laboratory and radiology testing, and schedule surgery. Marlena helps to make the entire preoperative process as smooth and efficient as possible.

Gina

Medical Biller
Gina is a certified medical biller and has worked exclusively in bariatrics since 2001. She handles all of Dr. Oliak's billing and is always willing to answer any billing questions you may have. Gina is an expert in getting your medical claims reimbursed appropriately.

Monina

Dietitian
Monina is the weight loss surgery dietitian for Chapman Medical Center. She provides preoperative and postoperative nutritional instruction, and is available for individual consultation both before and after surgery. She gives lectures on nutritional topics at our support groups on a regular basis. Her dedication to helping patients through the entire weight loss process, from before surgery to long after surgery, makes her an indispensable member of the team.

Melissa

Psychologist
Dr. Bailey-Arizpe is a California licensed clinical psychologist who specializes in weight loss surgery patients. She performs psychological evaluations before surgery, and provides one-on-one counseling as needed after surgery. She also moderates our gastric bypass support groups and is a frequent speaker at our LAP-BAND® support groups.