Scottsdale Weightloss Center

Plenity, Phentermine and Contrave: What’s the Difference?


Plenity, Phentermine, and Contrave are all used for weight loss but is one more effective than the other or has fewer side effects? Dr. Craig Primack, an obesity medicine doctor at SWLC, provides some general information and guidelines about each perception weight-loss tool:

how plenty weight loss fills the stomach

About Plenity

Plenity is a new weight loss pill as of Fall 2020 and is only available via prescription from doctors. It’s actually marketed as a “medical device” rather than a drug because it doesn’t affect the body’s hormones.Plenity can be used to treat overweight (BMI>25), obesity (BMI>30), and even lower levels of excess body weight than other medications.

How Plenity Works

The Plenity weight loss pill is made from cellulose and citric acid. The patient ingests 3 tablets and 16 oz of water before lunch and dinner. Plenity tablets swell 100 times their original size, taking more space in the stomach and gives the user a feeling of fullness (satiety). After that, it moves through the intestines and passes with bowel movements.

Plenity’s Side Effects

Since Plenity isn’t absorbed by the body, side effects are less common than other weight loss medications. Possible side effects of Plenity include:

  • abdominal pain
  • bloating
  • constipation
  • cramping
  • diarrhea
  • gas
  • irregular bowel movements

How Phentermine weight loss drug affects the brain


Phentermine is a stimulant-based appetite suppressant. It increases metabolism and acts directly on the appetite centers of the brain, an area called the hypothalamus. Used with diet and exercise, phentermine treats overweight and obesity. As of the most common weight-loss drugs, phentermine is one of the least costly and is safe for long-term use.

How Phentermine Works

Phentermine stimulates the central nervous system. As a result, it increases your heart rate and blood pressure, then decreases your appetite.

Phentermine’s Side Effects

For most people, phentermine increases energy so it’s used with caution on patients with anxiety. It is also not safe to use in many patients with heart disease and diseases of rapid heart rate. Common side effects of Phentermine include:

  • Constipation
  • Dry mouth
  • Increased heart rate
  • Nervousness
  • Tingling or prickling sensation
  • Sleeplessness

How contrave weight loss drug affects the brain

About Contrave

Contrave is a prescription-only weight loss drug that decreases appetite. It’s particularly helpful for cravings and food addiction. Containing two medicines, bupropion, and naltrexone, Contrave is FDA approved for long-term use.

How Contrave Works

Contrave stimulates the hunger and reward center of the brain. It raises levels of dopamine to reduce hunger and control cravings. Contrave doesn’t affect the metabolism, so it’s safe to use in people with heart disease.

Contrave’s Side Effects

Common side effects of Contrave include:

  • constipation
  • dry mouth
  • diarrhea
  • dizziness
  • headache
  • insomnia
  • nausea
  • vomiting


There is no right medication for everyone. Choosing the best medication, device, or a combination of both depends on the person. Your obesity medicine specialist will combine medication, diet, behavior change, and physical activity to optimize not just losing weight, but also weight loss maintenance.

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