About Us

FortisBMI® offers a comprehensive, multidisciplinary approach to weight loss and healthy living.  We pride our program on the education that each patient will receive.  Our multidisciplinary team consists of bariatric surgeons, certified bariatric nurse, registered and licensed dietitians, program navigator, and insurance specialist.   Our physicians and staff have decades of experience helping patients who have struggled with their weight. We have developed this program to help meet those challenges. 

Our goal is to make our patients healthy. During the initial consultation, our physicians discuss medical needs and personal desires of each patient. Through shared decision making with our patients, we develop a customized treatment plan for each patient using a combination of healthy eating, exercise, anti-obesity medications and/or nonsurgical and surgical options.

Next, our physicians and staff guide our patients through their weight loss and healthy living journey over the next several months. Whether your goal is big or small we are there with you every step of the way.    

Our Team

Sina Matin, MD, FACS, FASMBS

Dr. Matin is highly experienced in bariatric surgery, revisional bariatric surgery, and minimally invasive techniques such as advanced laparoscopic and robotic surgery.

He’s active in the American Society of Bariatric and Metabolic Surgery, Texas Association for Bariatric Surgery and the Clinical Robotic Surgery Association.

Dr. Matin operates at and serves in bariatric clinical leadership roles at hospitals affiliated with Baylor Scott and White Health, Texas Health Resources, Medical City Healthcare, Methodist Health System, and other independent local hospitals.

And while his accolades and clinical skills are very impressive, he is down to earth with his patients. They immediately feel comfortable and confident with him and in their surgical outcomes, even before they enter the operating room.

Julio Rivera, MD, FACS

Dr. Rivera has been a practicing physician since 2001 and has helped patients on their weight loss journey for over a decade. He brings extensive training and experience in minimally invasive bariatric surgery, advanced laparoscopic abdominal procedures such as robotic bariatric surgery, and an unsurpassed commitment to patient care.

Dr. Julio Rivera is Board Certified by the American Board of Surgery, is a Fellow of the American College of Surgeons, and is a Fellow of the American Society for Metabolic & Bariatric Surgery. Patients rave about Dr. Rivera’s ability to explain complex procedures and make the process of weight loss as pleasant as possible. Dr. Rivera also speaks fluent Spanish, making the journey less complex for our Spanish-speaking patients.

Shahid Shafi, MD, FACS, CEO

Dr. Shafi helps patients on their weight loss and healthy lifestyle journey, specifically focusing on the non-surgical side. He enjoys teaching patients about Obesity as a chronic disease and how to put exercise and healthy eating choices into their everyday life. For him personally, this includes bicycling running, walking, and portion control. Dr. Shafi doesn’t like to deny people the food they love – by helping patients discover a sustainable balance of exercise and healthy meal planning.

A lifelong learner, Dr. Shafi’s education has included Southern Methodist University in Dallas, University of Pennsylvania, the Johns Hopkins University, and University of Medicine and Dentistry of New Jersey. Dr. Shafi has been a practicing surgeon since 1998. He is board certified in General Surgery and a Fellow of the American College of Surgeons.


Susan is dual board certified in family practice and acute care. She has spent 30 years working in various healthcare settings, including family practice, cardiology, cardiovascular surgery and intensive care. The most gratifying practice has been helping patients treat the disease of obesity. “It is incredible to have the opportunity to  help patients improve their quality of life, reduce their medications, improve weight-related medical problems and simply feel better!” Susan lives in Flower Mound with her husband and son. In her spare time she enjoys being active outdoors, traveling  and spending time with family & friends.



Registered Nurse Manager Bariatric Coordinator

Kim Ewton received her Bachelor of Science degree in Biology and Nursing (BS and BSN). She began as a charge nurse and continued upward into management, where she continues today. She was one of only a few nurses nationwide to receive the initial certification in bariatric nursing (CBN), which continues to be her passion now for 18 years. She also is a Registered Nurse First Assist (RNFA). In addition to her CBN she also obtained a certification in the operating room (CNOR). She was also one of the first nurses in the state of Texas to specialize in the Transoral Incisionless Fundoplication procedure. Because of the uniqueness of this procedure, she was involved with a clinical study which resulted in her publishing an article in 2011, “Short-term safety and symptomatic outcomes of transoral incision less fundoplication with or without hiatal hernia repair in patients with chronic gastroesophageal reflux disease” in The American Journal of Surgery. Kim has a compassionate heart and believes that patient care is of the utmost priority. She holds memberships with the American Society for Metabolic and Bariatric Surgery, Texas Association of Bariatric Surgeons and Obesity Action Coalition.

Outside of the office she enjoys traveling and spending time with her husband, Tim and 4 kids.

Ashley Kadlubar, MS, RD, LD

Registered Dietitian

Ashley received her Bachelor of Science degree and went on to complete her Masters of Science with a Major in Nutrition and Minor in counseling at Texas Woman’s University in Denton following her dietetic internship there. She is a registered and licensed dietitian. She has over 10 years’ experience working in bariatrics and weight management. She has a passion for education and enjoys working both individually with clients along with leading interactive-group class and cooking demos. Her professional goal is to provide patient centered care aimed at achieving lifelong health and wellness through nutrition, lifestyle, and physical activity. Ashley enjoys the lake, fishing, camping and making messes in the kitchen with her kids. She lives in Denton with her husband, Jonathon, and two kids.

Jessica Johnson MS, RD, LD

Registered Dietitian

Jessica completed her Bachelors of Science degree, dietetic internship and Masters of Science degree in Nutrition from Texas Woman’s University. After completing her education, she became a Registered and Licensed Dietitian Nutritionist. She has worked with surgical and non-surgical weight loss patients in San Antonio and Dallas her entire career and loves it! Seeing patients achieve their weight loss goals through proper diet and physical activity, gain confidence and a better quality of life is what drives Jessica’s passion to work with her patients on a daily basis. Long term Jessica would love to become a certified provider in Obesity and Weight Management and Certified Diabetes Educator.

In her spare time Jessica loves to travel, cook and try new restaurants with her husband, Henry, and cheer for the University of Kansas men’s basketball team- Rock Chalk! Recently, she moved to McKinney with their new puppy and baby on the way.

Antonio MS, RD, LD

Registered Dietitian

Antonio joined FortisBMI® in 2019. He is passionate about helping patients achieve their weight loss goals.

Tracey Roth

Patient Navigator Metabolic and Bariatric Surgical Clinical Reviewer

Tracey has been in the medical field since 1996. She has worked exclusively in bariatrics for over 10 years. Tracey navigates patients through the multi-step process of gaining insurance approval and scheduling procedures. Tracey has extensive experience working with insurance companies and employers to help patients access their benefits. She specializes in authorizations for first time procedures, revisions and difficult cases. She is a certified Metabolic and Bariatric Surgical Clinical Reviewer which supports the quality initiatives set forth by American Society for Metabolic and Bariatric Surgery. She has a passion for helping patients achieve a healthier life. In her spare time, she enjoys spending time with her three children, family and friends.

Casey Whiffin

Administrative Assistant

Casey has been a medical administrative assistant for 19 years in multiple specialties with a focus in bariatrics for 8 years. She especially loves coordinating care for bariatric patients and helping ease the stress of scheduling, filing disability paperwork, and requesting medical records. Casey enjoys working closely with patients to help them achieve their long-term goals. In her spare time, she enjoys spending time with her family and friends and playing with her dog.