The Hernried Center’s medical team sets the standard for excellence in obesity care.

The medical team at The Hernried Center for Medical Weight Loss offers years of specialized experience helping the overweight and obese of the Sacramento area. Each doctor and nurse practitioner was trained by Dr. John Hernried himself and upholds the values of excellence and patient-oriented care that we’re known for.

Sharon Ball, MD


Dr. Ball grew up in the Chicago suburbs and has worked in a variety of inpatient and outpatient settings during her career. She is passionate about helping patients achieve a healthy weight, physical fitness, a wholesome relationship with food, and a reversal of their cardiovascular risk factors. In her spare time, she enjoys reading, gardening, traveling and the company of her family and friends.


Board-Certified: Internal Medicine, Geriatric Medicine

Residency: Internal Medicine, Letterman Army Medical Center, San Francisco, CA

MD: University of Illinois, College of Medicine, Chicago, IL

BS: Biology, cum laude, DePaul University, Chicago, IL


Professional leadership positions:

  • Assistant Medical Director, The Hernried Center, 2004-present
  • Brigade Surgeon, US Army, Germany, Persian Gulf War, 1990-1991
  • Teaching Staff, Internal Medicine Residency Program, Letterman Army Medical Center, 1989-1992



  • Honors Program Graduate, DePaul University, Chicago, IL
  • Health Professions Scholarship Recipient, Army Medical Corps
  • Army Achievement Medal, Operation Desert Storm


Rajinder Trewn, MD


Dr. Trewn has been in clinical practice for the past 21 years. Prior to joining The Hernried Center, she spent several years working in primary care, holding numerous positions in a variety of settings, including inpatient, outpatient, nursing home, urgent care, women’s health and many more. She most recently worked as a staff internist with the US Department of Veterans Affairs. From her many years spent treating chronic medical conditions, Dr. Trewn has seen the devastation obesity can have on one’s health. This experience motivates her to help people safely lose weight, and then keep it off for a lifetime. Her patients appreciate her attentive listening and easygoing personality. In her spare time, Dr. Trewn loves to volunteer in the community, take walks with friends, and travel with family.


Board-Certified: Internal Medicine

Diplomate: American Board of Obesity Medicine

Residency: Internal Medicine, State University of New York, Buffalo, NY

Post-Doctoral Scholar: Nutrition and Lipid Lab, University of California Davis, Davis, CA

MD: Christian Medical College, Punjab, India


Arline Yen, MD


Dr. Yen was previously in private practice as a general endocrinologist in Dallas, Texas, where she was involved with the care of many patients with diabetes. She is pleased to be a member of The Hernried Center’s multi-disciplinary team. She is dedicated to helping people achieve healthier weights in order to halt the development and reverse the progression of obesity-related diseases, such as diabetes, hypertension, heart disease, and sleep apnea. In her free time, Dr. Yen enjoys playing the piano, attending her children’s sporting events, and spending time with extended family.


Board-Certified: Internal Medicine, Endocrinology

Fellowship: Diabetes and Endocrinology, Scripps Clinic and Research Foundation, La Jolla, CA

Residency: Internal Medicine, University of San Diego Medical Center, San Diego, CA

MD: University of Texas Southwestern Medical School, Dallas, TX

BS: Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA



  • Southwestern Medical Foundation Scholarship
  • Tau Beta Pi, National Engineering Honor Society
  • Phi Beta Kappa, National Honor Society


Dean Tomlin, MD


Dr. Tomlin was born and raised in Sacramento. After completing his residency, he worked in family practice for a number of years, treating babies, adults and geriatrics. With a growing need for weight management expertise, he switched his area of specialty to bariatrics. Dr. Tomlin is married with two young boys. Outside of work, he is heavily involved with youth basketball. His other interests are family, raising alpacas, biking, youth sports and coaching.


Board-Certified: Family Practice

Diplomate: American Board of Obesity Medicine

Residency: Co-Chief Resident, Family Practice, Sutter Family Practice Residency Group, Sacramento, CA

MD: George Washington University, School of Medicine, Washington, DC

BS: Kinesiology, Psychology, University of California, Los Angeles, Los Angeles, CA

Member: American Academy of Family Physicians, American Society of Bariatric Physicians, The Obesity Society, American College of Sports Medicine, California Academy of Family Physicians



  • Chancellor’s Service Award for Community Service, University of California, Los Angeles, Los Angeles, CA


Anthony Huynh, DO


Board-Certified: Internal Medicine

Diplomate: American Board of Obesity Medicine, American Board of Physician Nutrition Specialists

Fellowship: Nutrition and Bariatric Medicine, Geisinger Medical Center, Bariatric Surgery Center of Excellence, Danville, PA

Residency: Internal Medicine, Tufts University School of Medicine, Caritas-St. Elizabeth Medical Center

DO: Nova Southeastern University, College of Osteopathic Medicine, Ft. Lauderdale, FL

BS: Life Science with distinction, Nova Southeastern University, Farquhar Center for Undergraduate Studies, Ft. Lauderdale, FL

Member: American Society for Metabolic and Bariatric Surgery, American Society of Bariatric Physicians, American Osteopathic Association, Florida Osteopathic Medical Association


Margolo Parson, NP


Margolo attended University of California, Davis as an undergraduate and University of California, San Francisco for her Master of Science in Nursing. Margolo worked for 16 years in family practice in the Napa Valley and 5 years in Yolo County with CommuniCare Health Centers. She has always enjoyed working with patients of all ages and backgrounds, and she especially likes helping people feel better mentally and physically. Margolo is elated to be working with a program that can offer real solutions and support to those seeking weight loss. When Margolo is not at work she can be found playing with her two children, gardening, or cooking up healthy new recipes. When you meet Margolo, be sure to say hello to her in Spanish. Margolo spent a year living in Spain!


Lori Arguello, NP


Lori earned her Bachelor of Science in Nursing from California State University, Sacramento in 2004. She then went to work as a registered nurse in cardiac, trauma, and surgical critical care settings. Later, she attended the University of Illinois at Chicago where she graduated with her Master of Science in Nursing in 2009. Her master’s project, Evaluation of an Advanced Practice Nurse – Managed Diabetes Clinic for Veterans, was published in The Journal for Nurse Practitioners July/August 2010 edition. From 2010 to 2015, she worked in a cardiology group in both inpatient and outpatient settings. Lori is passionate about preventative care, nutrition, and empowering patients to take control of their health. Along with cardiology and obesity, she also has interest in treating diabetes. Lori’s hobbies include running, world traveling, reading, cooking, and shopping at Nordstrom.


Shelly Rodgers, NP


Drawing on her thorough foundation in nutrition, Shelly loves educating people about the health benefits of eating well, including disease prevention and overall well-being. Practicing at The Hernried Center has given her the opportunity to make a real difference in people’s lives, and she feels immense satisfaction when sees improvement. As a caregiver, she always tries to work with people to pinpoint their needs and offer the care that will best benefit their life. She graduated with honors from Columbia University’s School of Nursing, and patients and staff value her for her knowledge and helpful attitude.




Rosemarie Alpay, NP


As a certified people-person, Rosemarie loves partnering with patients to help them along their weight loss journey. She views herself as a facilitator and a cheerleader, and always makes decisions with patients, rather than for them. Rosemarie has had her own struggles with weight, which gives her the empathy that has been crucial to her success as a caregiver. She received her Master of Science in nursing from University of California, San Francisco, has 35 years of nursing experience, and is also a Zumba instructor.




Amber D. Briner, NP

Amber D. Briner

Graduating with a Bachelor of Science in Nursing from the University of Indianapolis in 2004, Amber worked as a registered nurse for several years, primarily in hospital cardiac units. She cared for many patients whose conditions could have been vastly different if interventions to their health had been made sooner. From that experience, Amber knew that she wanted to work in a medical setting that would give her the platform to help patients implement changes to improve their health before developing more serious conditions. Her personal experience with a family member’s struggle with obesity and related health consequences adds to the understanding she brings to medical weight loss. Amber earned her Master of Science in Nursing from the University of California San Francisco in 2012. She has also served as a clinical nursing instructor and worked as a nursing volunteer in several places including Haiti. Amber enjoys spending time hiking, kayaking, and camping with her family and two children.


For more information on our medical team, call 800-815-4881. You can also request a free phone consultation by using our easy online form.

*Disclaimer: Individual weight loss results may vary. Diligently following your program will increase your chance of success. All Hernried Center programs are run by licensed medical professionals, but this website does not constitute medical advice.