Plenity – A New Weight Loss Pill

Plenity is a new weight loss pill designed to create a sense of fullness. It is backed by a single study where users had an average weight loss of 22 pounds. Not an effective way to achieve ideal weight, but may help some people when combined with diet and exercise.

I’ve been seeing TV commercials for Plenity, and I have found them confusing. They say it is made from naturally derived building blocks found in fruits, vegetables, cellulose, and citric acid. It contains no drugs, and yet it requires a prescription. Prescription-only meds are usually drugs. What’s going on here?

Plenity is not FDA approved as a drug. It is “FDA cleared” as a class II medical device that works by mechanical means. The website says it is:

…indicated to aid weight management in adults with excess weight or obesity, a Body Mass Index (BMI) of 25-40 kg per meter squared when used in conjunction with diet or exercise…when Plenity is combined with water, small hydrogel particles are formed. These hydrated hydrogel particles do not clump together, rather they mix with food and promote a sense of fullness.

Three capsules are taken with 16 ounces of water 20 minutes before lunch and dinner. A four-week supply costs $98.

Plenity is not for everyone. You can answer a series of questions on their website and a medical professional will tell you if you are eligible, and if you are, a US-licensed physician will write you a prescription. I answered the questions honestly and was correctly told I was not eligible.

A strange requirement

Warning: Plenity prescriptions can only be filled at a single online pharmacy, GoGoMeds. This bizarre requirement makes me suspicious and I don’t know of any other prescription products with similar limitations. They don’t offer any explanation. GoGoMeds generally has good reviews but was characterized as “a possible fraud” and “a complete scam” by some online reviewers.

The study

The GLOW study, a randomized, placebo-controlled trial of Gelesis 100, which apparently is the same thing as Plenity, was published in Obesity in 2019. A summary states:

Findings: Mean weight loss was 6.4% in the treatment group compared with 4.4% in the placebo group (P = 0.0007). Significantly more patients in the treatment group achieved ≥5% weight loss compared with those in the placebo group (59 vs. 42%), and 27% of patients in the treatment group lost ≥10% of their body weight compared with 15% in the placebo group.

According to the Plenity website, average weight loss over 6 months was about 22 pounds. I wondered how it would compare to just drinking 16 ounces of water 20 minutes before meals. I’m guessing that wouldn’t be as effective, but it might be somewhat effective and would be less expensive.

Conclusion: No miracle drug, but modestly helpful

So far, effectiveness has been shown in only one placebo-controlled trial. Diet and exercise must be continued. It doesn’t work well for everyone: 6 out of 10 users lost at least 5% of their body weight; the other 4 didn’t. It appears to have fewer side effects than other weight loss products. Not a way to achieve ideal weight, but probably worth trying for patients who understand that it is only an aid and not a final solution. I hope they will be encouraged enough by a 22-pound weight loss to continue losing weight with or without Plenity.

This article was originally published in the Science-Based Medicine Blog.

Dr. Hall is a contributing editor to both Skeptic magazine and the Skeptical Inquirer. She is a weekly contributor to the Science-Based Medicine Blog and is one of its editors. She has also contributed to Quackwatch and to a number of other respected journals and publications. She is the author of Women Aren’t Supposed to Fly: The Memoirs of a Female Flight Surgeon and co-author of the textbook, Consumer Health: A Guide to Intelligent Decisions.

Scroll to top