For decades, obesity has grown in prevalence, becoming one of the primary health concerns for modern America. Unlike many other conditions, the causes of obesity are well understood and can largely be ascribed to lifestyle factors like diet and exercise (though this is certainly not always the case). In other words, the steady rise in the percentage of Americans who are obese is causally related to the steady increase in caloric intake and decrease in activity levels amongst the population.

With the causes of obesity being so well understood, one might imagine the solution to be straightforward – just eat less and exercise more. In reality, this intuitive response to the problem is not always productive, as many patients who attempt to gain control over their weight are unable to achieve their desired outcomes, despite making substantial changes to their lifestyles. For some of these individuals, prescription medications exist that can give them a boost in their efforts and help them finally arrive at a healthy weight.

Prescription Weight-Loss Medications: An Overview

Who are they intended for?

Though the average American may like the idea of a taking a simple pill or injection to drop a pound or two, weight loss medications are not intended for general use by mildly overweight individuals. These products are specifically designed to treat patients with more severe cases of obesity, especially those who experience secondary health consequences because of their weight.

In considering whether a patient might be suited for weight-loss medications, a doctor will generally begin their assessment by reviewing the patient’s BMI. BMI, or Body Mass Index, simply represents the relationship between a person’s height and weight. Viewing weight in proportion to height is useful because the range of healthy weight for any person will vary largely due to the size of their frame. However, many other factors can determine how heavy a person can safely be, including their lean body mass, age, activity level, and medical history. Thus, though doctors refer to BMI as a starting point for their assessment, they will generally wish to review other factors as well.

Bearing in mind the limitations discussed above, a BMI of 30 or greater (or 27 or greater, where weight-related comorbidities are present) will likely indicate to doctors that a patient may be suited for weight-loss medications. Doctors may also consider whether lifestyle modifications have been attempted and will often advise patients to rigorously attempt to address their weight issues non-pharmaceutically if they have not already done so.

Who are they not intended for?

While many prescription weight loss drugs are reported to be generally safe and effective, they have also been determined to be unsuitable for certain groups due to unique health challenges or circumstances. For example, pregnant or breastfeeding women are typically advised against taking weight-loss medications, as the substances can affect the health of their child. People with a history of disordered eating or body dysmorphia may also be cautioned against such medications for concern of triggering further episodes.

If a patient uses one of these medications for a period of time without any indication of success, a doctor may advise that they discontinue the medication, and may also recommend trying an alternative. To this end, doctors should be monitoring and evaluating their patients for side effects or complications, and may decide that the risks of adverse health effects associated with continuing treatment outweigh any health benefits the patient is experiencing. Always defer to a trusted physician when making any changes to your medical treatment, including starting or stopping any of the medication mentioned in this article.

Expected outcomes

The success of any weight loss regimen will depend on many factors, and with so many different medications available, it is not possible to provide a general description of their efficacy. Different drugs can have different average success rates, and can also have varying efficacy between individuals. The drugs may also work better or worse depending on the lifestyle circumstances of a patient, their own health history, genetics, and many other factors.

With all that said, there are some general statements one can make about the likely efficacy of weight-loss medications as a whole. Research comparing the weight-loss success of groups using prescription medications in conjunction with behavioral changes versus those employing behavioral changes alone has shown that the medicated groups were able to lose 3 – 12% more of their starting weight than their unmedicated counterparts. As mentioned, one should be cautious about overgeneralizing such figures to all medications and patients, however the efficacy of weight-loss medications has generally been established in the scientific literature.

Side effects and concerns

In general, medications are only approved for use once their safety and efficacy have been established to a reasonable degree. Even so, such medications are not completely safe, and patients should thoroughly discuss the risks of any medication with their doctor before deciding to undergo treatment. Due to the possibility of complications, many doctors will strongly urge patients to avoid taking weight-loss medications purely for cosmetic reasons; they are meant as a tool to reduce the risk of harm associated with having an unhealthy body composition.

It is not uncommon to experience some unpleasant side effects when starting any new medication. The side effects one can expect with any particular weight-loss medication will vary, but generally these medications can cause gastrointestinal distress of various forms. Nausea, vomiting, and diarrhea are some not-uncommon examples of these types of effects. In many cases, the frequency or severity of these events will decrease over time.

Please note that more serious complications can occur with many weight-loss medications. While these tend to be less common than the more benign effects, patients should be informed of the risks of starting a new medication before doing so. Be sure to consult with your doctor about the likelihood of experiencing adverse effects from a new medication before starting, and review the literature included with your prescription before beginning a course of medication.

Expense and coverage should also be considered. Though a weight-loss medication may be determined to be medically necessary for you by your doctor, your insurance provider may feel differently. Unfortunately, many of these medications, particularly the newest additions to the list, carry a hefty price tag that make them a non-starter for most people without coverage. Also, while some off-label weight-loss drugs might be beneficial, being non-FDA-approved precludes them from insurance coverage in nearly every case.

Popular Examples

At the time of this article’s drafting, the FDA has approved six medications for long-term use in the treatment of chronic weight issues. However, medications are commonly prescribed “off-label” to treat conditions for which they have not yet been explicitly approved; as such, there are certain drugs which are given off-label for weight-loss despite not being officially indicated as such.

This section will offer a brief exploration of some of the more popular medications prescribed on- and off-label for the treatment of chronic weight issues in adults.

The GLP-1 modulators

Making waves recently in weight-loss circles are several drugs belonging to this class of medication. Big names from this category like Ozempic and Wegovy have entered the mainstream due to their association with household celebrity names and for their apparently dramatic results. However, they represent a small slice of a much larger category of similar medications.

GLP-1 receptor modulators affect the metabolism in ways that have made them useful in the treatment of type 2 diabetes. They accomplish these effects by interfering with the normal function of the body’s GLP-1 system, which plays a role in appetite, digestion, and insulin sensitivity. These effects have been found to also have the potential to assist with weight loss, though not all the drugs in this category have been officially recognized as such. As a result, some of these drugs may only be prescribed off-label for weight loss. Other factors may also differ between these medications which warrant a closer look.

Approved for weight-loss

At the time of this article’s publication, the only two GLP-1 receptor agonists FDA-approved for weight-loss are Wegovy (semaglutide) and Saxenda (liraglutide). These two medications are similar, with some important differences.

Saxenda is like Wegovy’s older brother; years before semaglutide had even been approved for treating diabetes, the FDA had already recognized Saxenda as a legitimate choice for weight-loss. Like semaglutide, liraglutide began its existence as a type 2 diabetes treatment (under the brand name Victoza). It was not unique at the time, as many other anti-diabetic GLP-1 receptor agonist options already existed. However, Saxenda made history as the first in its class to receive FDA approval for weight loss.

Since then, Wegovy has followed suit and joined the FDA-approved ranks. However, whereas Saxenda required daily injections, Wegovy’s once-weekly dosage schedule offers a significant advantage in convenience. Wegovy has also been reported to offer greater results, with some studies showing up to 10% in patients taking Wegovy compared to those taking Saxenda. Side effects between the two medications are generally similar, though individuals may have very different experiences with each medication.

Off-label only

In the United States, doctors are empowered by law to exercise their medical judgement in prescribing medications for purposes for which they are not specifically indicated. This principle means that, despite not being approved for weight loss, many of the medications in this section have been often prescribed as a means for patients to improve their weight loss success.

Perhaps the most notable entry in this section is Ozempic. This semaglutide formulation is only approved for type 2 diabetes, despite containing precisely the same active ingredient as Wegovy. Nevertheless, this drug has made waves for its potential as a weight-loss aid, thanks in large part to promotion from major influencers online.

Closely related to Ozempic is Trulicity, another GLP-1 receptor agonist known generically as dulaglutide. Due to its similarity, there is not much to say in the way of a comparison between this product and other GLP-1 receptor agonists like Ozempic. Like the others, Trulicity may be prescribed off-label for the treatment of chronic weight issues or for its intended purpose of treating type 2 diabetes in adults. The efficacy and side effect profiles of Trulicity and Ozempic are generally comparable. However, these drugs may not be perfectly interchangeable, and patients should not assume that they can switch from one to another without first seeking guidance from their doctor.

Lastly, let’s look at Mounjaro (tirzepatide), a unique entry in the GLP-1 family. This medication doesn’t quite fit neatly in the category of GLP-1 receptor agonists; though it does have some capacity to modulate activity at GLP-1 receptors, this is not its sole mechanism of action. This unimolecular drug can also interact with a different receptor site known as GIP that also plays a role in metabolism and insulation secretion. The overall result of activating both receptors is a synergistic effect that can produce greater outcomes than a sole mechanism of action alone. However, patients should note that Mounjaro is only approved for treating type 2 diabetes and may not necessarily be more effective at aiding weight loss than the other GLP-1 receptor agonists.

Orlistat

Though drugs like Ozempic and Wegovy have taken up a lot of space in the domain of weight-loss aids as of late, they are hardly the only category of contenders. As it turns out, the GLP-1 receptor system is far from the only aspect of our physiology that can be manipulated to facilitate weight loss.

Take Orlistat, for example. This FDA-approved weight-loss aid interferes with the body’s ability to secrete enzymes that digest fats, thereby reducing the uptake of dietary fats during the digestive process. The drug may have other impacts on the digestion of carbohydrates that assist with weight loss.

However, Orlistat represents a relatively old technology. Approved in 1999 – roughly two decades prior to many GLP-receptor agonists – Orlistat’s age reveals itself in comparisons of efficacy and side effects against newer entries. For example, one study showed Orlistat led to weight loss of 8.5 lbs in one year, compared to weight loss of 18 lbs in the same year amongst subjects taking Saxenda.

Conclusion

Striving to keep to a healthy body weight can be a difficult task these days. Many of us struggle to watch what we eat and push ourselves on the treadmill, only to find that the numbers on the scale hardly move at all. While this may constitute an annoyance for some people, others, whose weight is so excessive that it may contribute to negative health outcomes, have legitimate cause for concern if they cannot bring their wight within a healthy range.

Though not in every case, some of these individuals may consider asking their doctor to assess their suitability for prescription weight loss medication. A doctor may feel that one of the many options available may just be a medically useful and prudent addition to your weight loss regimen.