Optifast is considered to be the benchmark of liquid diets. Since the mid 1970’s, it’s treated over 1,000,000 obese patients, and has been proven effective in over 80 clinical studies. To participate in Optifast, you must see a participating doctor and have a physical exam – plus get regular monitoring throughout the plan. This is to make sure you are healthy enough for the rapid weight loss that is expected, and that you will be monitored for any risk factors that you may have. You also receive support, counseling, and lifestyle education. You’ll also receive an activity/exercise plan that is tailored just for you.

The diet is an 18 week plan. The first 12 weeks are purely liquid. It’s followed by a 6 week plan that incorporates regular food back in to the daily routine. During the liquid portion of the plan, you’ll have your choise of mixes for shakes and soups, or ready-to-drink cans of meal replacement shakes. The meal replacements are balanced with vitamins and minerals, so you should not have to add any additional supplements to your meal plan.

This diet is effective, but expensive depending on your eating habits prior to the diet. Expect the initial workup to cost around $500-$600, plus the purchase price of meal replacements which amount to around $100 a week. It is expensive, but subtract what you normally spend between meals, snacks, fast food and restaurants and the difference probably isn’t very much.

According to Optifast, you should expect to lose 2-4 pounds per week, and 50% of participants keep ‘enough weight off to improve health long term’.


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Posts By 3FC
  • Millicent Tree

    The Optifast diet is an indefensible scam and potential killer that the FDA should outlaw. I assert this from first-hand experience.

    Years ago I enrolled in the program and spent several months on the plan: 500 calories per day of an albumin-based powder that came in three flavors to be mixed with water. That’s it; nothing more.

    At first, like most of the people in my well-heeled group, I was ebullient. I lost 70 pounds in four months and was full of energy. (After the first few days there are no hunger pangs because the body goes into stinky-breath ketosis.)

    Then the problems began. Even though I was in excellent health with vital signs being monitored twice monthly (which was supposed to include a full a blood workup), I developed cardiac arrhythmia.

    I went immediately to the luxurious, well-appointed Optifast Center where I was placed upon a table and hooked up to an EKG while two of their medical people argued over whether I was having PVCs (premature ventricular contractions) or PACs (the less serious premature atrial contractions). I never did learn which, as without any kind of parting advice—and certainly no apology—I was immediately thrown out of Optifast’s program. I shall not describe that particular cinema-worthy scenario as I am saving it for my book.

    Using good common sense for a change I sought out a cardiologist who diagnosed the problem as potassium depletion due to electrolyte malfunction caused by this idiotic starvation (his words) diet. His prescription was a return to a sensible eating plan consisting of actual food, and heavy on the spinach and bananas. After a short time the arrhythmia ceased. And in a matter of months, having blown thousands of dollars on the Optifast program, I had gained back all the weight and more.

    I strongly believe that the Optifast diet destroyed my metabolism when I was an otherwise normal, active 36-year-old.

    In the passing years I have undertaken every diet on the planet, each time losing a few pounds and then quickly gaining back those plus many additional. As a result, my current weight is well over 300 pounds on my 5-foot 9-inch medium frame. (And I was never obese as a child; nor are any others in my family history, to this degree .)

    All causative medical factors including thyroid and adrenal problems have been ruled out. Physically, there is nothing wrong with me other than the usual side effects of morbid obesity: arthritic and non-bending knees (pre-disposed by genetics but greatly worsened by my weight); a hip that is rapidly deteriorating; sleep apnea; and insulin resistance that has not as yet led to full-blown diabetes.

    Now I am being pressured to undergo bariatric surgery—and the invasive, irreversible type rather than the less intrusive Lap-Band. I do not want to capitulate to having my digestive organs chopped up and permanently rearranged. But unless I can finally see some lasting results with a reasonable weight-loss program I may have to submit to this ghastly procedure. And for that, I am firmly convinced, I can thank Optifast.

  • Jess

    Wow….Reading the previous poster’s story is horrifying, because my mom is on this. She never did do ONLY liquid though, I know she eats some solid food every day, for dinner and I think a little throughout the day. She has lost some weight, but I’m going to tell her about this. Thanks for sharing your story…

  • Optifast Fan

    I have had a completely different Optifast experience than the other poster. Optifast is finally the “diet” that has worked for me. Going on this program was the best decision I’ve made for myself in a long time. I’ve tried just about every diet out there and Opitfast is finally the one that has worked for me.

    I lost 73 pounds in 24 weeks. I was on what is called full meal replacement. I drank three shakes and ate two bars a day. That would equal just a little over 800 calories a day. On days that I workout, I add an extra meal. This diet is not the 500 calories as the other poster stated. The program is called Optifast 800 for a reason. If I got hungry, I could snack on a pickle or celery. I did drink bouillon to keep my sodium levels up.

    It sounds like she had a horrible doctor. That’s too bad. The doctor that has supervised my weight loss has been wonderful. Also, his office offers a 20-class course that has classes taught by professionals from different disciplines. One week we will have a psychologist speak while the next could be a registered dietician. These classes help set up the clients for long term weight loss success.

    If you are considering the Optifast program, do the research. It is not for everyone. It sounds like there is a difference in care given at Optifast clinics. While I do sympathize with the above poster, Optifast did not cause her to weigh “well over 300 pounds”. I wish it could have helped her like it helped me.

  • aly

    The first poster obviously had or was predisposed to a health issue. Reducing calories should not harm an otherwise healthy person. If she was 300 pounds to begin with, then she already had these issues (probably just didn’t show up).

    I’m sorry that you have to go to surgery. I wish optifast or any other healthy eating regime could have helped you. If you really want to avoid surgery, I know you can lose the weight. It may take years but what’s the alternative. You can do it!!!

  • Free At Last

    Millicent, you have been such a help. I think I need to go on the Optifast plan, because all this time I thought my excess weight was do to my own poor, unhealthy choices and lack of excercise. I’d feel a lot better about myself if I could blame someone else, namely Optifast. tI’s about time. I’m tired of taking responsibility for my weight gain. Thank you, Optifast. I will no doubt want to sue you as well for causing me to eat the whole cheese cake. And thank you Millicent for showing me how to blame someone else. I may get fat, but it won’t have to be my fault anymore. Well, off to the fridge…

  • Elisabeth

    Hmmm, I disagree with this post. I am currently on optifast – my shakes/bars and soups total 960 calories alone, and then I am required to have 5 servings of green vegetables a day plus 2 teaspoons of olive oil. So, I end up around 1200 calories a day, which is not starvation at all. I am eating more vegetables on this plan than I have ever eaten in my life. 2 big salads a day plus extra veggies at night.

    So, if you follow the program the way it is intended and written, this will not happen. The vegetables provide extra potassium in addition to the shakes and bars.

    People who don’t follow the program as it is written have problems…

  • jamey

    I did the Optifast program two years ago, lost over 100 pounds and the only problem I had with the program was occasional irregularity. I no longer take high blood pressure medication and I have new energy. I am living my life. Millicent I am sorry you had such a bad experience but now they give potassium supplements and monitor blood every two weeks. I have regained none of my weight and I credit that to my ability to exercise more in addition to proper eating.

  • Jack

    *Years ago I enrolled in the program and spent several months on the plan: 500 calories per day of an albumin-based powder that came in three flavors to be mixed with water. That’s it; nothing more.*

    As far as I’m aware, you weren’t on an Optifast diet. They have always recommended 2+ cups of low starch, low calorie vegetables and salad per day. Salads like spinach.

    This story smells fake.

  • Pam

    I am currently on Pathway 1 of Optifast, which by the way, is not liquid only. In addition to soups and shakes, one can consume two bars, which are quite tasty. It totals 800 calories a day. I started the plan on December 1st and have lost 31 pounds so far. I am occasionally hungry, but that typically happens when I exercise more than 30 minutes a day, and I need to learn how to live with “hungry” and not automatically reach for a snack, which I used to do. It’s what got me to the point where I needed to do something. I will do Pathway 1 for another four weeks then transition to a combination of the meal replacements and a healthy meal. I am sorry Millicent had a bad experience, but I have to say that I am very pleased with the results and the support I get from the staff at the center I attend.

  • Anne

    I have had a great experience with Optifast. I did the Optifast 800 program in 1995 and I kept the weight off until 2003 (when I had a major depressive episode and could not stop eating). I have finally saved enough money to do Optifast 800 again and I am pleased with the results. They had my old file and would not start me on the program without the permission from my regular doctor. I love the program because it is easy, the chocolate shakes taste great, and they offer classes/lectures/maintenance visits. It is an extreme diet but it is possible to have a great experience with it. Just make sure you learn healthy exercise habits and take the classes they offer.

  • Ivan

    Personally, I’m at a complete loss to understand why anyone would go on such an unnatural diet. I’ve found that by eliminating grains, refined sugar, and dairy products from my diet and eating only vegetables, fruit, and lean proteins I can safely lose all the weight I need to lose. In my opinion this OPTIFAST plan is nothing more than a scam.

  • Helene


    Since you can lose all the weight you want then you should not be reading this review. There are many reasons people are overweight and when you are a busy single parent the ideal diet is not always accessable. Being a parent puts you last when your children need you. Going on an extreme diet like this one is a way to lose and help teach you new habits so when you transition back to all food you bring new habits with you.

  • Laura

    Millicent must have been on the “old” Optifast plan which only had shakes, nothing else, and was 450 calories per day. This is the diet that Oprah was on back in the 80’s as was I. I lost 65 pounds in 13 weeks. It was fantastic, but I guess was not for everone, Millicent, which is why there was medical monitoring. the current Optifast plan has 800 calories per day and has shakes, bars and soup. the wieght loss is not quite so drastic but it is still fast. I have lost 20 lbs in the last 4 weeks, been taken off of the Metformin I was on for daibetes, and am working toward getting off of my bp meds. I feel so much better and I am one of these people that does well on something this strict. We are not allowed however to eat anything other than Optifast during the weight loss portion of the plan. I think that Canada calls it Optifast 900 and adds about 100 calories a day of veggies, etc.

  • Patricia

    Interesting responses. I went on Optifast in Sept of 2005, I lost a total of 120 pounds. I have kept the weight off for 4 almost 5 years. I never did get that last 50 pounds off and now, 6 1/2 years later I am looking to go back and do the program to finish this off once for all. I was on 800 calories, which was 5 shakes a day. No veggies, no bars, no extras and no cheating!

    I realize going into the process that most of my weight problems were between my ears and food will be a struggle all my life, why not struggle with food closer to my goal weight? Right?

    But one of the biggest variables is having a strong social support system which I would love to set up. I am into eating good energy dense foods, but have also developed Hashimoto’s disease in the last 12 months so it will be interesting to see how it all works out.

    I love to read of your success!