Plenity Review: What are "Medical Device" Pills?

Plenity Review: What are "Medical Device" Pills?

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Disclaimer: None of the information in this article constitutes medical advice. All statements are merely the opinion of the writer(s). We recommend that patients follow their doctor’s guidance in regard to prescription medication.

Plenity is an FDA-cleared weight management aid. The brand's website claims that Plenity can help you eat less so that you can lose weight.

But is Plenity proven in clinical trials to cause weight loss? And if so, how much weight loss can it cause? Does Plenity cause side effects? And why is the treatment described as a "medical device"?

In this article we'll answer all of these questions and more, as we review a clinical trial on Plenity to determine if the drug causes weight loss, and if so, how much.

We'll discuss side effects, explain why Plenity is "FDA-cleared" rather than "FDA-approved," and share our concerns about two inactive ingredients in Plenity.

We'll also document the cost of the treatment, and feature unsponsored customer reviews.

Does Plenity Cause Weight Loss?

clinical trial published in the Obesity journal analyzed the effects of Plenity on weight in overweight patients.

Patients were instructed to consume a diet 300 calories below their maintenance level, and also supplemented with either Plenity or with placebo pills.

Over the course of the 24 week trial, patients on Plenity lost 6.4% of their body weight, and patients on placebo pills lost 4.4% of their body weight.

This study was poorly designed in our opinion. The trial participants had fasting blood glucose levels between 90 and 145 milligrams per deciliter (mg/dl) . The range for pre-diabetes is 100-125 mg/dl, and anything over 125 mg/dl is diabetes according to the CDC.

Just because a treatment works on diabetics and pre-diabetics doesn’t necessarily mean it will translate to similar results for non-diabetics.

While it's true that some of the trial participants had blood sugar levels ranging between 90-100 mg/dl which would be considered in the "normal" range, we believe the trial should have been conducted exclusively on patients with normal blood sugar levels, because Plenity is marketed to all patients regardless of blood sugar level and is not considered a weight loss medication for pre-diabetics and diabetics.

We can't find any other clinical trials on Plenity for weight loss, and this is the only study referenced on Plenity's About page at the time of updating this article, so this may be the only efficacy study.

We consider Plenity to have the potential to cause weight loss, but we would be more impressed if a second trial in patients with normal blood sugar levels validated the results from the trial cited above.

What Does "FDA-Cleared" Mean?

Plenity is "cleared" but not "approved" by the Food and Drug Administration (FDA) because Plenity pills are actually classified as medical devices rather than drugs. 

According to the FDA, the clearance process involves a manufacturer submitting information proving that their medical device is safe and functionally equivalent to a device already on the market.

FDA approval, which is required for prescription drugs, involves the FDA reviewing clinical trial data on a drug to determine if it's safe and effective.

The FDA categorizes Plenity as a medical device because it has a physical mechanism of action. It takes up space in the stomach, rather than having a systemic effect like most oral medications do. 

For the most part, the ingredients in Plenity are not absorbed by the body. As documented in the drug's FDA clearance letter, "Plenity passes through the digestive system."

Real People Try Plenity

A YouTube creator named "TamkinSpice" has a review of Plenity after five months of use that includes a before-and-after image:

A YouTube creator named "MaciExplainsItAll" claims to have gained weight while using Plenity:

Does Plenity Cause Side Effects?

The clinical trial on Plenity that we cited previously documented no significant difference in side effects between Plenity users and placebo, which is a good sign. 

On Plenity's site, fullness, bloating, abdominal pain and flatulence are listed as potential side effects. 

Dietary fiber intake alone can cause these side effects, and we would assume these are caused by the cellulose. These side effects are relatively mild for a prescription drug.

In our opinion, Plenity has a superior side effect profile to many other weight loss medications.

Many of the weight loss drugs that we've reviewed on Illuminate Health have a "black box" warning on their label that details risk of severe side effects, but Plenity has no such warning.

How Does Plenity Work?

Plenity takes up space in the stomach which makes users feel full faster. This is the same reason why increasing fiber intake can cause weight loss, as we documented in our article on how to lose weight fast.

The drug is composed of two active ingredients: cellulose and citric acid.

Cellulose is an insoluble plant fiber contained in nearly every plant food, such as apples, oranges, kale and bananas. 

We consider this to be an effective active ingredient for a weight loss drug, given that fiber intake is clinically shown to be associated with weight loss.

Citric acid is a preservative and flavor enhancer which may cause whole-body inflammation in a small subset of patients according to a medical review published in the Toxicology Reports journal.

Plenity claims that these two ingredients combine and react with water in the stomach to create a sense of fullness which reduces overeating. 

Plenity's FAQ page includes a safety information section which states that patients allergic to the following compounds should not take the drug: cellulose, citric acid, sodium stearyl fumarate, gelatin, titanium dioxide.

This suggests that sodium stearyl fumarate, gelatin and titanium dioxide are the inactive ingredients in Plenity.

Titanium dioxide is banned for use as a food additive in the EU, due to concerns over genotoxicity, which means that it may damage DNA.

How Much Does Plenity Cost?

At the time of updating this article, Plenity costs $98 per month out-of-pocket.

However, some health insurers may fully or partially subsidize the cost. We recommend that patients considering Plenity call their health insurance company first to check if the treatment is covered.

This is a relatively low retail price for a prescription weight loss medication.

In our Wegovy reviews article, we documented a weight loss medication that costs over $1,400 out-of-pocket.

Our Clean Weight Loss Picks

There are food-based nutrients which have been shown in medical studies to be effective for weight loss.

Dietary fiber was shown in a medical review published in The Journal of Nutrition to cause 16 pounds of weight loss in 6 months when combined with moderate caloric restriction (750 calories per day below baseline).

MBG Organic Fiber Potency+ is our top fiber pick because it's certified organic, provides 7 g of fiber per serving and costs under $1.85 per serving at the time of updating this article.

MCT oil was shown in a meta-study to cause more than one pound of weight loss over 10 weeks. This equates to potential annualized weight loss of 6 pounds per year with less than one tablespoon's worth of MCT oil per day.

Performance Lab MCT Oil is our top MCT oil pick because it's certified organic.

Ginger intake "significantly decreased body weight" according to a 2019 meta-study on ginger and weight loss that analyzed data from 14 clinical trials.

Pique La Ginger is our top ginger product, because it's an organic tea in convenient crystallized form, and all that's needed is to pour the powder into a glass and add hot water.

All three of the products mentioned in this section are entirely free of additive ingredients that we consider to be unhealthy.

We are not suggesting that any of the products referenced in this section are as effective as Plenity, or any other FDA-cleared weight loss treatment. Rather, we're sharing options that patients with an aversion to pharmaceutical medication may wish to speak to their doctor about.

Pros and Cons of Plenity

Here are the pros and cons of Plenity in our opinion:


  • Works mechanically not pharmacologically
  • May be safer than other weight loss prescriptions
  • Unlikely to cause side effects
  • Clinically shown to work
  • Affordable
  • FDA-cleared
  • May be subsidized by health insurance


  • We question the methodology of clinical study
  • Contains citric acid
  • May contain titanium dioxide
  • Requires a prescription
Stay up-to-date on our research reviews


Plenity is clinically shown to cause weight loss, although we have some questions about the methodology of the study proving so.

The average blood sugar level in trial participants was in the pre-diabetic range, and we figure a trial on non-diabetic patients would be more useful, given that Plenity is not currently marketed as an exclusive treatment for patients with pre-diabetes or diabetes.

The mechanism of action of this device is similar to fiber: it takes up space in the stomach and contains zero calories, so it should reduce overconsumption of calories.

Plenity is unlikely to cause side effects, and seems superior from a safety perspective than most pharmaceutical weight loss drugs in our opinion.

Plenity costs under $100 per month out-of-pocket at the time of updating this article, and this cost may be reduced with health insurance subsidies. This is one of the lowest retail prices for any prescription weight loss treatment we've reviewed to date on Illuminate Health.