Plenity: effectiveness, uses, side effects

last updated: Oct 20, 2021

4 min read

Most people you know have probably struggled with their weight at some point in their adult lives—it’s estimated that over 70% of U.S. adults have excess body weight and over 40% have obesity (Centers for Disease Control and Prevention, 2021).

While overweight and obesity are becoming more prevalent, these conditions are not without their risks. Obesity is associated with many health risks, including type 2 diabetes, heart disease, and high blood pressure (Giruzzi, 2020).

Lifestyle changes such as diet and exercise are the usual recommendations for addressing these issues, but these interventions might not be enough for some people. Various types of weight loss medications and surgeries have also been developed to offer extra help to those who can’t achieve the results they’d like through diet and exercise alone (Giruzzi, 2020).

Recently, a new type of weight loss treatment has hit the market that’s safe, effective, and is associated with minimal side effects. This new treatment is called Plenity (Giruzzi, 2020).

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What is Plenity?

Plenity, also called Gelesis100 during the research studies, is a new type of super absorbent gel developed to help people with overweight and obesity lose weight. It was first approved by the U.S. Food and Drug Administration (FDA) in April 2019 for adults with a body mass index (BMI) of 25–40 when used in combination with a lower-calorie diet and exercise (Giruzzi, 2020). 

The most exciting and unique fact about Plenity is that it’s considered a medical device, not a medication. This is because it helps you with weight management by mechanical means and not by being absorbed in your body (Giruzzi, 2020).

People who have excess weight can use it, even if they haven’t yet developed obesity, unlike most medication options. Also, unlike medical weight loss options, Plenity doesn’t have any restrictions on how long you can use it (Giruzzi, 2020).

Plenity is made of capsules that you can swallow. Each capsule contains thousands of superabsorbent hydrogel particles that are about the size of a grain of salt. They are made primarily from cellulose and citric acid. When the capsules dissolve in your stomach, they combine with water and hydrate up to 100 times their original size (Gelesis, 2021).

While the FDA has approved it, most insurance plans don’t cover Plenity (Tirthani, 2021).

How does Plenity work?

Plenity is an oral capsule that helps you feel fuller after meals and can help you to manage your weight. It works directly in your gastrointestinal (GI) tract instead of being absorbed into your bloodstream. This is why it’s considered a device instead of a medicine (Gelesis, 2021).

You take Plenity with two glasses of water (16 ounces). The Plenity capsules open in your stomach, releasing their superabsorbent hydrogel particles. These particles absorb the water you drank to expand into a three-dimensional matrix that fills up to occupy about a quarter of your stomach when fully hydrated (Giruzzi, 2020).

The gel matrix mixes with the food from your meal and creates a larger volume in your stomach and small intestines. This makes you feel fuller sooner than you usually would (Giruzzi, 2020).

The Plenity gel stays expanded while it moves through your small intestine. When it enters your large intestine, it starts to break down. The water that is released is reabsorbed into your body, and the cellulose material leaves your body through your feces (Giruzzi, 2020).

In clinical studies, more participants lost weight with Plenity than those in the placebo group. One study found that 59% of people taking Plenity lost at least 5% of their starting body weight. 27% were able to lose at least 10%. The participants taking Plenity were twice as likely to lose 5–10% of their body weights than those taking a placebo (Greenway, 2018).

People with prediabetes or type 2 diabetes who weren’t already taking medication had a six times greater chance of achieving at least a 10% weight loss with no increased safety risks (Greenway, 2018).

How do you take Plenity?

If your healthcare provider prescribes Plenity, you should take it with water twice a day, 20–30 minutes before lunch and dinner. Each dose of Plenity consists of three capsules packaged together in a pod (Gelesis, 2021). 

For each dose, you should do the following (Gelesis, 2021):

  1. Swallow one dose (three capsules) with water.

  2. Drink two additional 8 oz glasses of water after taking the capsules.

  3. Wait 20–30 minutes and then begin your meal.

If you forget to take your dose before your meal, you can take it during or immediately after eating (Gelesis, 2021). 

Plenity can affect the way that your stomach absorbs medications. If possible, you should take your medications at a different time than when you take Plenity. If you have to take medicines with food, wait until you begin your meal to take them (Gelesis, 2021).  

People with diabetes who take oral medication to lower their blood sugar should monitor their blood sugars closely. Your healthcare provider might have to adjust your regimen (Gelesis, 2021). 

What are the side effects of Plenity?

No medical device or medication is suitable for everyone. All treatments have the risk of some side effects. Your provider can tell you if Plenity is safe for you to use and help you manage any adverse events you experience.

You should not use Plenity at all if you are currently pregnant or if you are allergic to any of the ingredients (cellulose, citric acid, sodium stearyl fumarate, gelatin, and titanium oxide) (Giruzzi, 2020).

Plenity should be used carefully by anyone with a history of (Giruzzi, 2020):

  • Gastroesophageal reflux disease (GERD)

  • Stomach ulcers

  • Heartburn

  • Crohn’s disease

  • Any surgery that changed how food moves through your GI tract

  • Narrowing of the GI tract

Plenity is very new to the market. While studies have found it safe and effective in the short term, long-term studies on its effects are still needed.

The most common side effects of Plenity reported were (Greenway, 2018):

  • Diarrhea

  • Bloating

  • Infrequent bowel movements

  • Flatulence

  • Constipation

  • Nausea

  • Abdominal pain

Studies did not find that Plenity affected the levels of vitamins A, B1, B2, B6, B9, B12, and D in your body, which can be a problem with some other weight loss treatments (Greenway, 2018).

How do you get Plenity?

Plenity is only available by prescription. If you think that you need some help losing weight in addition to diet and exercise, contact your healthcare provider. It’s important to tell your provider if you are taking any other medications or supplements to prevent interactions.

You and your healthcare professional can decide if Plenity is right for your situation. They can also help you develop a plan to make healthy dietary changes, find ways to include more physical activity in your life, and set healthy expectations about how much weight you can expect to lose with Plenity.


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

Gelesis. (2021). Instructions for use product: plenity. Plenity® | FDA-Cleared Aid in Weight Management. Retrieved from

  • Giruzzi, N. (2020). Plenity (oral superabsorbent hydrogel). Clinical Diabetes: A Publication Of The American Diabetes Association, 38 (3), 313–314. doi: 10.2337/cd20-0032. Retrieved from

  • Greenway, F. L., Aronne, L. J., Raben, A., Astrup, A., Apovian, C. M., Hill, J. O., et al. (2018). A randomized, double‐blind, placebo‐controlled study of gelesis100: A novel nonsystemic oral hydrogel for weight loss. Obesity: A Research Journal, 27 (2): 205-216. Retrieved from

  • Tirthani, E. & Quartuccio, M. (2021). Non-dieting approaches to treatment of obesity. [Updated Jun 23, 2021]. In: StatPearls [Internet]. Retrieved on Oct. 11, 2021 from

How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

October 20, 2021

Written by

Ellyn Vohnoutka, BSN, RN

Fact checked by

Steve Silvestro, MD

About the medical reviewer

Dr. Steve Silvestro is a board-certified pediatrician and Associate Director, Clinical Content & Education at Ro.

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