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The Landscape of Weight Loss Medications: An Overview

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The Landscape of Weight Loss Medications: An Overview


Weight loss is a journey that many embark on for reasons ranging from improving cardiovascular health, optimizing metabolic health, or simply getting health to improve longevity and promote health optimization. While diet, exercise, and lifestyle changes are the cornerstones of weight management, there are instances where these might not be enough. This is where weight loss medications can play a role. In this article, we will delve into the world of pharmacological interventions for weight loss, summarizing the options, how they work, and their potential benefits and risks.

Understanding Obesity and the Need for Medication

Obesity is a complex disease characterized by an excessive amount of body fat. It is typically defined by a body mass index (BMI) of 30 or higher. The condition is associated with an increased risk of numerous health issues, including diabetes, heart disease, stroke, and certain types of cancer.

For some individuals, weight loss medications are recommended as a tool to assist with weight loss efforts, especially when obesity-related health conditions are present. These medications are not a cure for obesity but are used in conjunction with lifestyle modifications.

Types of Weight Loss Medications

Weight loss medications can be broadly categorized into prescription drugs, over-the-counter (OTC) drugs, and herbal supplements. We’ll focus on prescription medications, as they are regulated by agencies like the Food and Drug Administration (FDA) in the United States and undergo rigorous testing for safety and efficacy.

Key Weight Loss Medications and How They Work

Orlistat (Xenical®, Alli®)

Orlistat is available in both prescription strength (Xenical®) and over-the-counter form (Alli®). By inhibiting the enzyme lipase, Orlistat reduces the breakdown and absorption of fat in the gastrointestinal tract by about 30%. This unabsorbed fat is then excreted in the stool. In clinical trials, Orlistat has been shown to help patients lose about 5-6% of their body weight over one year when combined with a reduced-calorie diet and increased physical activity.

Phentermine (Adipex-P®, Lomaira®)

Phentermine is a sympathomimetic amine with pharmacologic activity similar to amphetamine. It suppresses appetite by releasing chemicals in the brain that affect the central nervous system. Phentermine is approved for short-term use (a few weeks), typically in individuals with a BMI of 30 or higher, or 27 or higher with an obesity-related comorbidity.

Phentermine-Topiramate (Qsymia®)

This combination drug merges the appetite suppression of phentermine with topiramate, an anticonvulsant that has weight loss side effects, possibly due to its taste alteration effect and increased satiety. Qsymia can lead to significant weight loss compared to placebo. However, due to its teratogenic effect (risk of birth defects), it is not recommended for use in pregnant women.

Liraglutide (Saxenda®)

Initially developed to treat type 2 diabetes, Liraglutide (Saxenda®) is an injectable medication that works by mimicking the hormone GLP-1, which regulates hunger and calorie intake. This medication is approved for long-term use and has been shown to lead to a weight loss of 5-10% of body weight on average.

Naltrexone-Bupropion (Contrave®)

Naltrexone-Bupropion is a combination of two FDA-approved drugs, naltrexone (used for substance dependence) and bupropion (an antidepressant). It is believed to work on two areas of the brain to reduce hunger and help control cravings. It’s approved for long-term use and studies suggest that it helps with a modest weight loss of ~5% of initial body weight over a year.

Potential side effects are headaches, nausea, constipation, dizziness, vomiting, dry mouth, and the risk of seizures at higher doses.

Semaglutide (Wegovy®)

Semaglutide, like liraglutide, mimics the GLP-1 hormone that targets areas of the brain that regulate appetite and food intake. Wegovy® was approved in 2021 for chronic weight management, clinical trials show an average weight loss of 14.9% of initial body weight over 68 weeks, making it one of the more effective options currently available.

Tirzepatide (Zepbound®)

Tirzepatide is the newest GLP-1 medication on the market that also has a dual action on GIP.  It, too, targets areas of the brain that regulate appetite and food intake while optimizing sugar and glucose levels and promoting healthy weight loss. Zepbound® wsa approved in 2023 for weight loss, clinical trials show an average weight loss of 20.9% of initial body weight, making it the most effective medication for weight loss to date.

Mechanism of Action

The mechanisms by which these medications aid in weight loss vary:

  • Appetite suppression: Medications such as phentermine reduce the feeling of hunger.
  • Fat absorption inhibition: Orlistat reduces the amount of fat that is absorbed in the intestines.
  • Craving reduction: Naltrexone-bupropion impacts the brain’s reward system, which can help minimize cravings.
  • Increased satiety: Medications like liraglutide and semaglutide increase feelings of fullness, leading to a reduction in food intake.


The effectiveness of weight loss medications varies among individuals. A reasonable expectation is a loss of 5% of initial body weight over a 12-month period when combined with lifestyle changes. This amount of weight loss has been shown to improve many obesity-related health conditions.  More novel medications, including semaglutide and tirzepatide, however, show promise for even greater losses of body weight and reduction in BMI while also showing promise in improving glucose control, decreasing rates of metabolic syndrome, and improving cardiovascular health metrics which may promote longevity and increased survival.

Who Can Benefit from Weight Loss Medications?

Not everyone who wants to lose weight should take these medications. They are typically prescribed for:

  • Adults with a BMI of 30 or higher.
  • Those with a BMI of 27 or higher and at least one weight-related condition such as hypertension, type 2 diabetes, or high cholesterol.

Potential Risks and Side Effects

All medications have side effects, and weight loss medications are no exception. Long-term use can also lead to tolerance, and these medications can interact with other drugs. Thus, it is crucial to discuss with a healthcare provider the potential risks and benefits.

Lifestyle Changes as a Foundation

While medications can provide a helpful boost in weight loss efforts, they are most effective when combined with lifestyle modifications, including:

  • Dietary changes: Adopting a calorie-restricted, balanced diet.
  • Increased physical activity: Engaging in regular exercise.
  • Behavioral changes: Implementing strategies to help modify eating and lifestyle habits to support long-term weight management.

The Role of Health Care Providers

Healthcare providers play a critical role in managing obesity with medications. Before prescribing, they will evaluate:

  • Weight history
  • Diet and physical activity level
  • Possible causes of weight gain
  • Weight-related health risks
  • Previous weight loss efforts

Providers will also monitor progress, side effects, and make adjustments as necessary.

Regulatory Considerations

Regulatory agencies like the FDA scrutinize weight loss medications for their safety and efficacy before they can be marketed. They also monitor these drugs once they are on the market for any long-term side effects.

The Bottom Line

Weight loss medications are not magic bullets, but they can be beneficial for individuals struggling with obesity and related health complications when used under medical supervision. They should be viewed as one component of a multifaceted approach to weight loss, which includes diet, exercise, and behavioral changes.

When considering weight loss medications, it’s essential to have a candid discussion with a healthcare provider to fully understand the potential benefits and risks. Weight loss medications can be a helpful part of a comprehensive weight loss plan for some individuals, but they must be used judiciously and in conjunction with a healthy lifestyle to ensure the best outcomes for health and wellbeing.

Ozempic®, Wegovy®, and Saxenda® are registered trademarks of Novo Nordisk.  Ivim Health has no affiliation with Novo Nordisk.  The compound semaglutide products available as part of Ivim Health’s Weight Loss Program are not made by Novo Nordisk or any company affiliated with Novo Nordisk.Zepbound® and Mounjaro® are registered trademarks of Eli Lily.  Ivim Health has no affiliation with Eli Lily.  The compound tirzepatide products available as part of Ivim Health’s Weight Loss Program are not made by Eli Lily or any company affiliated with Eli Lily.

Xenical® is a registered trademark of Cheplapharm Arzneimittel GmbH.  Ivim Health has no affiliation with Cheplapharm Arzneimittel GmbH.

Alli® is a registered trademark of GlaxoSmithKline.  Ivim Health has no affiliation with GlaxoSmithKline. 

Adipex-P® is a registered trademark of Lemco, Inc.  Ivim Health has no affiliation with Lemco.

Lomaira® is a registered trademark of Avanthi, Inc.  Ivim Health has no affiliation with Avanthi.

Qsymia® is a registered trademark of Vivus LLC.  Ivim Health has no affiliation with Vivus.

Contrave® is a registered trademark of Nalpropion Pharmaceuticals.  Ivim Health has no affiliation with Nalpropion.

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