5: Anti-Obesity Medications: Part 1

Mar 20, 2023

Long-term weight loss is extremely challenging, even with lifestyle changes.Only around 5% of people are able to lose 20% of their body weight with lifestyle changes alone. 

So while you may benefit from short-term weight loss, your hormones often end up working against you, increasing your appetite and lowering your metabolism. Willpower alone isn’t usually strong enough to fight these metabolic adaptations.

Since your hormones control your appetite and your metabolism, many researchers have focused on ways to help metabolic adaptations that our body naturally goes into.

Unfortunately not all physicians are educated in this area, so I want to run you through the pros and cons of 9 different anti-obesity medications, as well as discuss who qualifies for this medication. Hopefully this information will empower you in any conversations you may have around anti-obesity medication with your own medical team.

Who qualifies for anti-obesity medication?

Generally speaking, if your body mass index (BMI) is between 27 to 29.9 with medical comorbidities, OR over 30, then you qualify for the weight loss medications. This may be lower for certain ethnic populations, which is why it’s important to speak with a physician who is aware of these differences. 

In that overweight category of BMI (27 to 29.9), the medical comorbidities have to be related to weight in order to qualify. So for example, things like type two diabetes, high blood pressure, and high cholesterol. If the weight is 30 or over, that's the number that we start to use when we give the medical diagnosis of obesity.

If you do fall into those number brackets and would therefore qualify for these medications, it does not necessarily mean that it's appropriate. That is definitely a conversation that needs to be had with your doctor. 

It’s important to keep in mind that all of these medications have a lot of benefits and a lot of risks, which we need to weigh out for you.

Pros and Cons of Weight Loss Medications

1. Phentermine

This medication also goes by the name of Adipex among a few others, and has been around since 1959. Phentermine is a sympathomimetic amine that works on the central nervous system to suppress appetite and is a stimulant medication. It is an oral medication.


  • We see around 7% weight loss (5% + is significant with regard to health outcomes) and it does a great job with suppressing hunger.
  • It is super cheap and because it has been around so long, we know what to expect from it. Even if you don’t have insurance, it’s covered.


  • Because it's a stimulant, some people start to develop insomnia with it, even if they take it right in the morning. 
  • Some patients may also end up getting heart palpitations due to the stimulant nature.
  • Some of the effects such as dry mouth are not tolerable. 
  • Some states only approve it to be written three months at a time, and then there has to be breaks in between, despite knowing that people do extremely well long-term on phentermine. 
  • Depending on the doctor, an EKG may be needed. This means your heart needs to be checked out beforehand.
  • Because it's in the stimulant category, it's a controlled medication, so you're not able to get this through most telehealth services as you need face-to-face visits to monitor the heart closely. 

2. Qsymia

Qsymia is an oral, combination medication (a combination of phentermine and Topiramate, or Topamax) which has been around for about 10 years.


  • This one sees around 10% weight loss.This is the average but when you look at the studies, there will be a certain percent that have been able to lose 20% of their body weight. So with this medication, about 15% can lose 20% of their body weight. 


  • Brain fog
  • It is very contraindicated for pregnancy because you can get birth defects. The babies can get cleft lip and palate, which is really serious. And so, if there's a young woman, there needs to be a birth control plan.
  • If you have a history with kidney stones, this is not the medication for you. 

 3. Contrave

Contrave has two ingredients as well. It has one ingredient called Bupropion (brand name Wellbutrin). The other ingredient is Naltrexone. It is an oral medication.


  •  It's about a 7% weight loss. 
  • Where I see this being the most helpful is with cravings. For example, if someone always wants something sweeter at night, this is the medication that usually will move the needle the most for them. 
  • Decreases those food thoughts all the time. 
  • We can make generics of it. We need to sometimes use generics because unfortunately, the insurance industries don't want to cover these medications. They still see obesity as an aesthetic problem, and not the medical necessity. 


  • If you're someone whose alcohol patterns don't permit this, it will not be a medication for you. 
  • If you are on chronic opioid pain medications, the naltrexone part will block that so it’s not a medication for you. 

4. GLP-1 Agonists

For this group of medication, the majority of them are going to be SubQ, meaning a small injection right under the skin. There is one that is an oral option, however, it's not as effective. 

With Saxenda (Liraglutide), we see about 10% weight loss. It's been used since 2010. Saxenda is a once a day injection. 

Another one is called Semaglutide. If it's FDA approved for weight management, it's called Wegovy, which is a weekly injection. If it's for treatment of diabetes, it's Called Ozempic. 

The oral route of Semaglutide is the medication Rybelsus. That medication is about 15 or 16% weight loss. 


  • The really nice thing about these medications is that they delay stomach emptying, so you feel full quicker, and you're also going to get the ‘enough’ signaling in the brain so that you're not sitting there thinking about food all the time. You actually feel satisfied.
  • These medications are solving a real physiologic need that we have with the chronic treatment of obesity. Not only are they affecting the stomach as well as the brain, but they also have a lot of other positive effects, such as for the heart. One of the pros that I look at here is how many positive things it's impacting on the body, and the higher weight loss. 


  • The cons of this medication, is unfortunately the price. Insurance doesn't want to cover it, even though they have all the literature of people being able to lose the weight and keep it off, which they've never been able to do in the past. They just care about what the monthly cost is.
  • Some people also won't be able to tolerate the GI side effects, like feeling sick. What we do see is that the longer you're on the medication, the more these side effects go down. In addition, if you have the proper education when you start them, about how to hydrate, how to eat, and what to do, the outcomes tend to be a lot better.  

5. Tirzepatide (brand name is Mounjaro)

It is being used off lab for obesity but not yet FDA approved so not covered well by insurance unless someone has a type 2 diabetes diagnosis as well. This medication sees around 22% average weight loss, which is very exciting. Hopefully in the coming year here, they will have it FDA approved for weight management. I know those trials are going through and what's incredible here is that the numbers that you get with Tirzepatide are starting to be close to what you see with bariatric surgery. So it's really amazing that we have medications now that can mimic surgery.

6. Plenity 

This is actually a capsule that you take with water before meals. It's a hydro gel that increases your fullness with meals, like consuming a bunch of fiber. I think it's a nice addition for certain things, but only for the right person, and in the right place. 

The one thing about Plenity that's unique is that it’s indicated for a BMI that goes right down to 25. So this is sometimes for people that have lower amounts of weight to lose but they still want something. 

7. Orlistat

Orlistat limits fat absorption. It's over the counter, and is half strength compared to what the prescription is. The problem with Orlistat is that because it's blocking fat absorption, it can cause a lot of greasy stools and things like that. I find that it's only helpful sometimes if someone has really bad constipation from a GLP-1. Sometimes this can be added to kind of balance that out. 

It's typically a really old medication that's really not used that often. Something that I don't enjoy about it is because it's blocking fat absorption, you can sometimes get vitamin deficiencies because you're not able to absorb those properly. So there's a lot more monitoring that needs to go on if you use it. 

8. Lisdexamfetamine (goes by the name Vyvanse)

That's FDA approved for treatment of binge eating disorder. It's a controlled medication, so it really needs to come from the right provider, face-to-face. Some doctors are just not as comfortable writing for it for different reasons, and so although it is great, and it's FDA approved, it's likely it’s not being used as much as it could be. 

9. Metformin

I don't tend to think about this as a weight loss medication. The weight loss percentage is around 2%, which seems really insignificant but sometimes if there are things going on such as insulin resistance, we need to help that in order to move the needle on other things. 

Can you combine these medications?

Yes, we do combine some of these medications. 

For example, for someone who is on Wegovy and reaches 15% weight loss but then they stall, despite doing all the lifestyle changes, I might talk to them and find out they’re struggling with urges and cravings for certain foods at certain times. So then we might look at those patterns and see that adding Contrave is a good option for them.

There are a lot of patients that might be on combination medications but that is not right for everybody. I will also look within the first few weeks and months of someone being on the medication and if they're not losing weight or not losing appropriate amounts of weight, we will reassess. We don't want to increase the risk for side effects if they’re not getting all the benefits that you would expect. There are people where I will remove a medication if I don't feel it's helping them.