The FDA has approved several medications that can be used to treat obesity. Through seeing patients for weight management, I have come to realize that there is not a lot of information out there on the options and misunderstandings are frequent. In this article, I will highlight selected anti-obesity medications and discuss the pros and cons of each. However, first and foremost, please understand that these medications do not work on their own. Without following a strict healthy diet and incorporating regular exercise, the medications will not have a significant effect.
Magic weight loss pills
A common misconception is that there is a magic pill available. This is false. If this were true, everybody would know about it and the executive of the pharmaceutical company manufacturing such a pill would rival Amazon founder Jeff Bezos for the wealthiest person in the world.
What these medications can provide is an adjunct to diet and exercise to allow for maybe a few more pounds to be lost and in some cases, for the lifestyle plan to be easier to follow. Without further adieu, here are some of the available options.
Short-term anti-obesity medication
Phentermine has been available for decades and is available in generic form, making it one of the cheapest medications for weight loss. Phentermine is only FDA approved to be used for 3 months and works by suppressing appetite. In the stimulant category, other than appetite, phentermine amps everything up in the body. On the positive side, this means you’ll have more energy. Unfortunately, possible side effects include a faster heart rate, increased blood pressure, and anxiety.
Furthermore, phentermine can provide an initial boost in short term weight loss but requires you to keep up lifestyle modifications to be effective long term. Clinically, I have seen patients with an appetite rebound after going off of phentermine, eliminating any weight loss made while on the medication.
Overall, due to the side effect profile, short term usage requirement, and the possibility of reversal of weight loss upon discontinuation of the medication, I generally do not recommend phentermine.
Long-term anti-obesity medications
Orlistat (Xenical (RX only) and Alli (OTC; half strength))
Orlistat is also an older drug that works by impairing the absorption of fat from the intestines. The results are less fat digested and thus more fat excreted. However, a common adverse effect is that some patients experience abdominal cramping, oily stools, and stool leakage – a consequence of eliminating instead of absorbing fat.
This medication only works temporarily so it needs to be taken three times daily with meals. Because some fat-soluble vitamins are also eliminated, it is recommended to take a multivitamin before bed each night (generally hours after the last dosage of orlistat).
Generally, orlistat provides more weight loss than lifestyle modifications alone, at least 5% more on top of lifestyle modifications for half to two-thirds of patients. Orlistat is well tolerated by many and is the only weight loss drug that does not affect appetite. Furthermore, orlistat discourages patients from eating fatty foods. If patients were to continue to consume high-fat meals, they will quite likely experience the undesirable side effects listed above.
Obesity is a multifactorial disease and different medications work for different people depending on the underlying cause(s). As with all of the medications listed, if 5% weight loss is not achieved in 3 months (at least a third of patients will not meet the 5% target), then it is time to stop orlistat and try another medication.
Orlistat is my top option for patients who have high-fat diets that are having trouble weaning off these foods.
Belviq is an appetite suppressant that works on the hunger centers of the brain to produce a feeling of satiety. Similar to orlistat, Belviq can produce only a modest amount of weight loss in the majority of people and should be discontinued if you do not lose 5% or more weight in 3 months.
Belviq is the best option for suppressing appetite due to its low side effect profile. Clinically, I have found it to be effective in many patients. They not only lose weight but notice a change in their cravings. Also, Belviq has user-friendly dosing – once daily for the extended-release version and twice daily for the immediate-release version.
A caution for Belviq is that it should not be taken if a patient is on any medications for anxiety, depression, or other mental health disorders due to a drug interaction that can produce a rare condition called serotonin syndrome. Belviq is also not recommended for those with heart valve issues or heart blocks. The most common side effects that I have seen are headache, fatigue, and nausea. Mood changes are also possible.
Liraglutide is a medication that was initially (and still is) used to treat diabetes, called Victoza. It was found that when patients took the medication, they also had a side effect of weight loss. It was rebranded and given a second name as an obesity drug, Saxenda.
Saxenda is generally very effective for weight loss. In combination with a healthy diet and regular exercise, Saxenda can help people lose additional weight by suppressing their appetite. Unlike Orlistat and Belviq, Saxenda is an injectable medication, used once daily. These injections are given with a very thin diabetes needle into the abdominal fat. Dosing is done by escalation, starting at a lower dose and increasing weekly if well tolerated until the full dosage of 3.0mg is achieved. If intolerance occurs at higher doses, Saxenda can be continued at lower doses.
Saxenda actually has a higher average weight loss than the drugs previously mentioned. It also has more side effects and tolerability issues. An increased risk of a certain type of thyroid cancer has been found in lab rats with Saxenda. It is unclear if this is also true of humans. Therefore, it should not be taken by patients who have a personal or family history of thyroid cancer. Saxenda can also cause a rare disease called pancreatitis – inflammation of the pancreas. Symptoms of pancreatitis include severe abdominal and/or back pain and would need to be treated in the hospital.
Saxenda has several less serious side effects including nausea and vomiting, dizziness, changes in bowel habits (increase or decrease in frequency), mood changes, and headaches.
As listed above, Saxenda has its plusses and minuses. With greater average weight loss, but more possible side effects, it is my preferred medication for patients needing appetite suppression but who are on medications that interact with Belviq, such as mood stabilizers.
There are several other medication options for weight loss, but the main ones that I prescribe are Orlistat (Xenical or Alli), Belviq, and Saxenda. The last medication I will highlight is one that many of my patients have heard of through television advertisements. Contrave is a combination medication that combines two older drugs, bupropion, used for anxiety and depression, with naltrexone, used to manage alcohol or opioid dependence. Contrave works on the hunger center of the brain to suppress appetite and reduce cravings.
This all sounds great in theory and the makers of Contrave have several good studies to show that it works. The medication uses an escalating dose regimen similar to Saxenda, going up each week by one pill, starting at one pill daily in the morning and finishing at two pills twice daily.
In my experience, my patients have not tolerated Contrave very well. I have seen the medication discontinued for several reasons including fatigue, headache, and dizziness. It seems that discontinuation is more likely since the medication is comprised of two drugs, each having its own possible side effects. Therefore, Contrave is not one of my preferred medications.
Final thoughts on anti-obesity medications
There are several prescription medications available to assist in the treatment of obesity. However, they are meant to supplement diet and exercise. No medication works without the necessary lifestyle modifications. There is also no magic pill and no one medication that is a slam dunk above all the rest. This is because obesity is a multifactorial disease and each individual person has his/her own underlying biological reasons causing obesity.
If well tolerated, these medications can be taken for 3 months to see if 5% of the weight is lost. If not, another medication can be tried. If you are interested in going on anti-obesity medications, consult with your physician to find the best treatment for you.
What are your thoughts on anti-obesity medications? Share them in the comments below!