Meet the Advanced Bariatrics Team
Experienced, compassionate professionals dedicated to supporting you throughout your weight-loss journey.
John R. Cheregi, MD, FACS, FASMBS
Bariatric Surgeon
Dr. Cheregi’s specialty is bariatric surgery for medical weight loss. He understands the challenges that his patients face and has a personal passion for helping them achieve long-term success. By working closely with patients to choose the right procedure and make long-term lifestyle changes, Dr. Cheregi helps them envision (and realize) a new future.
Dr. Cheregi is fellowship trained in both advanced laparoscopy and bariatric surgery. His patients appreciate his positivity and his judgement-free approach to addressing their challenges. Dr. Cheregi emphasizes education, encouragement and collaboration to help his patients achieve their personal lifestyle goals.
I want my patients to feel that I’m here at every step of the way. This is a life-changing journey. From the very first conversation about the challenges you face – through surgery and follow-up – we are right by your side. We are committed to helping you reach your goals.
Hsin-Yi Chang, MD, FACS
“The ideal patient-doctor relationship is one in which both people are listening and learning. I want my patients to understand the pros and cons of every procedure we are discussing. Together, we will find the best path forward.”
Dr. Chang is recognized for her expertise in minimally invasive surgery, with a specialty in bariatric surgery designed to help patients achieve significant weight loss. She embraces a collaborative approach with her patients, understanding that each individual (and their journey towards wellness) is unique.
Dr. Chang’s goal is to provide her patients with a better quality of life, and her greatest reward is watching them achieve life-changing outcomes following bariatric surgery. Although the procedures she performs take relatively little time, the long-term results are extraordinary, in terms of overall health and life expectancy.
“I strive to provide each patient with a compassionate and effective healthcare journey that begins with understanding and empathy.” From the initial consultation through to post-operative care, I emphasize a collaborative approach where patients are empowered to make informed decisions about their health.”
Dr. Hoeltgen has a special interest in advanced laparoscopic surgery, robotic surgery, and bariatric surgery. He has significant experience in multiple advanced laparoscopic and robotic surgical techniques. Dr. Hoeltgen has served as a faculty member for several large laparoscopic surgery companies, teaching other fully trained surgeons advanced laparoscopic and robotic surgical procedures, including gastric bypass. Dr. Hoeltgen is a Diplomate of the American Board of Surgery and has subspecialty certification in Bariatric Surgery. He is a Fellow of the American College of Surgeons and the American Society for Metabolic and Bariatric Surgery (ASMBS). He is also a member of the Society for Gastrointestinal and Endoscopic Surgeons (SAGES). He is the Medical Director of Bariatric Surgery at Advocate Good Shepherd Hospital and has held may other leadership positions including Chairman of the Department of Surgery.
Dr. Hoeltgen fosters a supportive environment and aims to build trust and alleviate any anxieties associated with surgery. He believes in thorough communication, ensuring that each step of the surgical process is transparent and tailored to meet the individual needs of the patient.
Daniel Hoeltgen, MD, FACS, FASMBS
Vanessa Manzo, MSN, FNP-C
Nurse Practitioner
Obesity Medicine Certified
Vanessa received her Master’s degree in Nursing from Graceland University in 2019. She has been a nurse for 7 years. Her most recent experience has been in internal medicine managing chronic illnesses. Vanessa joined our bariatric family in January 2022. She is excited to be able to share her passion for educating patients to improve their health. By joining our team, Vanessa is no longer be treating patients’ comorbidities. Now, she plays a role in helping to resolve their comorbidities and improve her patients’ quality of life. Vanessa will be managing our medically managed weight loss program. She will also be providing pre-operative education and heading our future support group for patients. She will work side by side with Dr. Cheregi and Kiersten to continue to support and encourage our patients on their weight loss journey.
Kenia Williams
Bariatric Program Administrator
Kenia is the bariatric program administrator. She is an integral part of the bariatric surgical process.
She guides you through every step of the process from meeting with the dietitian and psychiatrist to scheduling surgery.
Kenia also helps you navigate the insurance process and personally calls to check on your benefits. She is very passionate about helping you succeed on the journey to becoming a healthier you.
Erin Jacob
Practice Manager
Erin ensures that our program and practice always keeps its focus on the health and well-being of our patients. It brings her great joy to be able to provide support not only to the physicians and staff but also to our patients.
Audra Wilson, MS, RD, CSOWM, LDN, CSCS
Lead Program Dietitian
Audra Wilson is a Board-Certified Specialist in Obesity and Weight Management, holds a Master’s Degree in Applied Science and Sports Nutrition from Concordia University Chicago and Bachelor’s degrees in Nutrition and Dietetics as well as Education from Northern Illinois University and a Bachelor’s in Agricultural Business from Illinois State University. She is also a Certified Strength and Conditioning Specialist through the National Strength and Conditioning Association and is an enthusiastic advocate for the power of exercise in health improvement. She has worked with weight management patients, pre-and post-surgical patients, patients struggling with disordered eating/eating disorders, and athletes for the past six years. She is passionate about helping patients to improve their relationship with food and reach all of their health and wellness goals
Jessica Barker, MS, RD
Program Dietitian
Jessica Barker received her Master’s Degree in Nutrition and Physical Performance from St. Louis University in 2009 and has been working with weight management patients for 11 years. She is a Registered Dietitian and a member of the Academy of Nutrition and Dietetics weight management practice group. Jessica is also a certified personal trainer through the National Academy of Sports Medicine and loves to coach people to enjoy movement and understand all of the long-term benefits of exercise. Jessica has a passion for the power of nutrition and healthy lifestyle changes in transforming our health and how we look, feel, and function each and every day.
Christine Komjathy, MS, RD, LDN
Program Dietitian
Christine Komjathy received her Masters Degree in Clinical Nutrition from Rush University in 2010. She has over 12 years of experience counseling patients on weight loss. Christine also spent 5 years in a University research setting studying the public perceptions of diets for weight loss. Being a Certified Group Fitness Instructor through the Academy of Sports Medicine, she also enjoys teaching classes to older adults and adults with disabilities.
