Home / Meet the Dietitians


At F-Factor you’ll work with a registered dietitian who is certified in F-Factor’s proprietary nutritional method, which is based on more than 20 years of clinical experience helping clients achieve their health and weight goals.


Tanya Zuckerbrot MS, RD photo credit Brian Marcus

Tanya Zuckerbrot, MS, RDis a dietitian and the creator of the F-Factor diet, which she has used for more than twenty years to provide thousands of clients with all the tools they need to achieve easy weight loss and maintenance and improved health and well-being. F-Factor is the leading dietitian-created program for weight loss and optimal health based upon fiber-rich nutrition that helps people effectively and positively improve their lives without disrupting their lifestyle.

Tanya has appeared on The ViewThe Today ShowThe Early Show, The Rachael Ray ShowMSNBCABC NewsGood Morning America Health, CBS Evening NewsExtraGood Day New York and in many other local and national media platforms. She is a nutrition news contributor for Fox News Channel and writes a weekly column for Foxnews.com.  

Tanya has been profiled in The New York Times, and has been featured in The New York Post, The New York Daily News, Town & Country, Elle, Vogue, Allure, Self, The Huffington Post, The Miami Herald, The Washington Post and Daily Mail.

Tanya is an international speaker and spokesperson. She has lectured for NBC Studios, The Discovery Network, Proctor & Gamble, Johnson & Johnson, G&E and Estee Lauder. Most recently Tanya became a Brand Ambassador for the retailer, Saks Fifth Avenue.

Tanya holds a Master’s degree in Nutrition and Food Studies from New York University and completed a two-year dietetic internship at NYU Medical Center. She is an accredited member of the American Dietetic Association, the Greater New York Dietetic Association, and a member of the National Association of Professional Women. Tanya completed her CDR Certificate of Training in Adult Weight Management as well as her CDR Certificate of Training in Childhood and Adolescent Weight Management. Tanya is a Medical Advisory Board Member of Sharsheret.

Tanya is the author of two bestselling weight loss books: The F-Factor Diet: Discover the Secret to Permanent Weight Loss (2006, TarcherPerigee), and The Miracle Carb Diet: Make Calories and Fat Disappear the F-Factor Way – with Fiber! (2012, Hachette Books).

Tanya resides in New York City with her husband and their children. 


Shana Rubenstein RD 1

Shana Rubenstein Pantirer, RD, F-Factor

Shana Pantirer, RD, is a Registered Dietitian, New York State-Certified Dietitian/Nutritionist, and the Senior Dietitian at F-Factor Nutrition where she specializes in weight loss and medical nutrition therapy for chronic conditions such as diabetes and cardiovascular disease. Her expertise also includes family and pediatric nutrition counseling.

Shana’s interest in nutrition began as an overweight adolescent with a insatiable sweetooth. At age 12, she attended a weight loss camp where she lost 15 pounds – an experience she describes as so ‘life-changing’ that it inspired her career choice helping those who struggle with their weight.

Shana holds a BS in Nutrition Science from Indiana University. As a Registered Dietitian, Shana’s clinical experience includes extensive work in hospitals and outpatient diabetes centers throughout Manhattan.  At F-Factor, she  says she is living her dream teaching people to take control of their weight and health by making better food and lifestyle choices.

Shana’s passion for nutrition extends into all areas of her busy life. She is an avid cook who enjoys creating recipes and trying new ingredients and preparation techniques. Shana and her husband Marc reside in Manhattan where they share their love of sports, fitness and adventure travel.

Shana is an active member of the American Dietetic Association and the Greater New York Dietetic Association.


Maria Stavropoulos, F-Factor

Maria Stavropoulos, is a dietitian at F-Factor Nutrition where she sees clients for weight loss and medical nutrition therapy for chronic conditions such as diabetes, hyperlipidemia, and hypertension. Through her expertise, she is able to help her clients reach personal nutrition as well as lifestyle goals.

Growing up in a Greek-American family in Brooklyn, Maria gained an interest in nutrition as a young teen where she learned the importance of healthy and balanced food choices while keeping an active lifestyle.

Maria holds a Bachelor of Science in Nutrition with a minor in Media Studies and a Master of Science in Nutrition from the Hunter College School of Public Health. She completed a year-long comprehensive dietetic internship residency through Aramark Healthcare Corporation where she gained extensive experience in both clinical and community nutrition as well as foodservice management at Bronx Lebanon Hospital Center and Richmond University Medical Center. In addition to her clinical work, Maria worked as an Audience Producer on ABC’s The Katie Show and The View, where she assisted with the production of health related segments such as “Katie’s Health Toolkit”. Maria’s interest and engagement in media opportunities has allowed her to implement nutrition education on larger platforms during her time at F-Factor Nutrition.

Maria’s passion for nutrition and food extends to some of her favorite activities, which include cooking authentic Greek dishes with her mother, coaching a local girls’ volleyball team, and sharing her knowledge with others through various social media platforms.

Maria is an active member of the Academy of Nutrition and Dietetics and Greater New York Dietetic Association. Maria is currently a part of the GNYDA Public Relations Committee.


Samantha Hass, R.D. F-Factor

Samantha Lee Hass, R.D., is a registered dietitian at F-Factor Nutrition, where she provides individualized nutrition counseling for weight loss and medical nutrition therapy for chronic conditions such as diabetes, hypertension, hyperlipidemia, and GI disorders. She also specializes in prenatal, postpartum and pediatrics.

While in high school in Miami, Samantha was diagnosed with Hashimoto’s disease, an autoimmune thyroid disorder, which is infamous for its effect on weight gain and inability to lose weight. In just a few months, Samantha had gained 15 pounds. She turned to exercise in hopes of losing the excess pounds, but was unable to lose the weight until she changed what was on her dinner plate. Following a high-fiber, high protein diet, in line with the F-factor philosophy, she was able to get back to her previous weight. 

Samantha attended New York University where she received her Bachelors in Nutrition and Dietetics and a minor in Psychology. She completed a 12-month clinical dietetic internship at New York-Presbyterian and was selected for their Nutrition Fellow program where she specialized in nutrition for pediatrics and obstetrics. Samantha is an active member of the Academy of Nutrition and Dietetics and several practice groups such as Pediatric Nutrition, Dietitians in Integrative and Functional Medicine and Nutrition Entrepreneurs.

Samantha says one of the perks of growing up in Miami and living in New York City is the culinary scene. She is a true “foodie” and loves to try new restaurants and host dinner parties for her family and friends. During her free time she enjoys playing tennis with her husband Andre, biking throughout NYC and traveling. Samantha understands what it means to be a busy New Yorker and wants to spread her knowledge of how to enjoy city life while making healthy food choices. 

Schedule an appointment

Share this page