Skip to main content

Sergey Lyass, MD

Bariatric Surgeon and Weight Loss Physician serving the Los Angeles area

Sergey Lyass, MD is a bariatric surgeon, weight loss specialist, and da Vinci® robotic surgery provider serving patients in Los Angeles, Glendale, and Marina del Rey, California. He received his medical degree from the 2nd Moscow Medical Institute (now Moscow Medical University) in 1985.

He was trained in general surgery in Israel at the Hebrew University-Hadassah Medical Center in Jerusalem, and did his internship at Mount Sinai Medical Center in New York City. Dr. Lyass completed both his surgical residency and his fellowship in minimally-invasive and bariatric surgery at Cedars-Sinai Medical Center in Los Angeles.

Dr. Lyass is board certified in general surgery. He has more than 25 years of experience performing surgery, including various types of minimally-invasive procedures and bariatric weight-loss surgeries using the da Vinci Surgical System.

Dr. Lyass is the author of more than 100 scientific publications and book chapters in leading medical journals. He is fluent in Russian and Hebrew.

Professional Education:

  • Internship: Mount Sinai Medical Center, New York, NY
  • Residency: Cedars Sinai Medical Center, Los Angeles, CA
  • Fellowship in Minimally Invasive and Bariatric Surgery: Cedars Sinai Medical Center, Los Angeles, CA.
  • 2006 – Board Certified in General Surgery
Meet Sergey Lyass, MD

Meet Sergey Lyass, MD

Success Stories


    Overall weight loss 155 pounds*


    I would like to share my before and after photos after my GBP surgery that Dr. Lyass performed on me. Before the surgery I weight over 375 pounds it is exactly one year later and I have lost 155 pounds now weight 220. Dr. Lyass saved my life. I no longer walk with a cane, I am working out and getting out every weekend.

    Before the Surgery I was a shut in afraid and ashamed to leave my house other then work.

    I recently flew on an airplane last month I finally can fit back in the world and it feels wonderful THANK YOU Dr. Lyass!!!!

    *Results may vary


    Weight loss so far 111 pounds and still losing*...


    Dr. Lyass, I cannot thank you enough for saving my life! I have lost 79 lbs since surgery 12/16/08. I was 341 in August of 2008. Now I weigh 230.  I feel wonderful!!!

    I have no medical problems and have had no complications at all. My life is so wonderful now. I have 95 lbs to go and I know I’ll be able to make it.

    Thank you again.

    *Results may vary


    Overall weight loss 128 lbs* 

    Thank you!

    *Results may vary


    Overall weight loss 111 pounds*


    Dear Dr. Lyass,

    I’m so very grateful for the surgery you did for me…. It has changed my life I am able to tie my shoes again also to play with my kids … I had the gastric bypass and my life is amazing… You're a great Doctor and I’m grateful to have known you..

    Thank you,

    *Results may vary


    Overall weight loss 71 lbs*


    I was the largest that I had ever been 265, I worked out 5 days a week and tried every fad diet out there. I was so depressed and even my social life and marriage was struggling due to my weight. I then began looking into surgery and came across the Lap Band procedure. I did a lot of research and realized that I was ready for a change and this was it. I had the surgery in June and weighed in at 250 and 4 months later I now weigh in at 194. I feel absolutely wonderful and not too much has changed other than my eating habits and my health. I had hypothyroid disease and sleep apnea and now I am off my meds and have so much energy and a clean bill of health. Dr. Lyass did my surgery and what an outstanding doctor. I felt really comfortable and he explained everything pre/post surgery.  Thank you so much Dr. Lyass, I owe you so much and would recommend you and the surgery to anyone.

    *Results may vary


    Lost 70 pounds in 7 months*


    Thank you.

    *Results may vary


    Overall weight loss 175 lbs*


    February 24th will be the one year anniversary of my surgery. To date I have lost 175 pounds. I am working out four days a week and walking at least four days a week. I started out wearing a size 4x shirt, and 56 pants and now wear a size XL shirt and 36 pants! I am still looking forward to losing at least another 25 pounds. I feel amazing. The surgery has changed my life in ways I never anticipated. I have followed all of the rules and guidelines you laid out and have not experienced any complications to date. This season I am back to riding my snowboard and bodyboard, which I have not done in 20 years. I went to Disneyland with my kids which I have never done. I am able to go to concerts and shows without worrying if I will be able to fit in a seat. I am off of my cholesterol and high blood pressure meds, as well as not having to use my CPAP machine any more.

    I can’t thank you and your staff enough for taking care of me and providing the service you do. I know it’s your job, and you earn a good living at it, but what you did for me has given me a whole new lease on life.

    *Results may vary


    Weight loss so far 50 pounds and still losing*...


    Hands down the best surgeon on earth. Dr. Lyass performed my sleeve gastrectomy on 09/22/15. My surgery was at brand surgical (most amazing staff I have ever seen!!!!!!!!) Dr. Lyass has answered any and every question I ever had--- from the beginning up until now!

    I have already lost FIFTY pounds!

    His technique is amazing and honestly I had absolute minimal pain.

    His nerve blocks are out of this world I didn't feel my abdomen or incisions for three days and by the time the numbness wore off I had NO pain.

    Thank you Dr. Lyass for changing my life for the better! You're amazing!!

    *Results may vary

Start your new life now!

  • Dr. Sergey Lyass and his staff are ready to help you reach your weight loss goals through bariatric surgery options. Depending on your current condition, past medical history and the amount of weight you want to lose, we have the right treatment option for you. 

    We are ready to provide you with all the information that you need to know about our treatments options. Feel free to contact us.

    We are looking forward to helping you start your new life!

Our Locations

Choose your preferred location

Calculate your BMI (Body Mass Index)

Input your current height and weight information to calculate your BMI (body mass index). You will receive your weight status category.

Click here for the BMI calculator

Patient Letter to Dr. Lyass*

Dr Lyass, I cannot thank you enough for saving my life! I have lost 79 lbs since surgery 12/16/08. I was 341 in August of 2008. Now I weigh 230. I feel wonderful!!!

Dr. Lyass did my surgery and what an outstanding doctor. I felt really comfortable and he explained everything pre/post surgery. Thank you so much Dr. Lyass, I owe you so much and would recommend you and the surgery to anyone.

I am very pleased with my care so far. The doctor understands that I had to pay for my procedure because my insurance would not cover it. I got an infection from the surgery and he took care of it as fast as possible. Dr. Lyass seems to care about me and wants me to do well. He keeps in close contact with you if you have any questions or concerns. He was the only doctor that wrote an email to me when I was looking for a surgeon.

*Results may vary