Medications for obesity aren’t often discussed. But they need to be, because just as patients with diabetes and depression can find relief from their medical conditions via pharmaceutical assistance, so, too, can people with obesity. Not every person with obesity requires medicine, but for those who do, treatment can be quite beneficial. These drugs work in different ways; some act as appetite suppressants, some block fat absorption, while others trick the brain into feeling full. Have questions? We have the answers you need.
We went to the nation's top obesity experts to bring you the most-up-to-date information possible.
Deborah Bade Horn, D.O.Medical Director; Assistant Professor of Surgery
Donna H. Ryan, M.D.Professor Emerita
Angela Fitch, M.D.Associate Director of the Massachusetts General Hospital Weight Center, Vice President of the Obesity Medicine Association
Remind Me: What Exactly is Obesity and How is It Diagnosed?
At its most basic level, obesity is an excess accumulation of fat that creates a risk to your health. It’s defined by a person’s Body Mass Index (BMI).
To calculate your BMI, plug your numbers into our BMI calculator, or do this relatively simple math yourself:
Divide your weight (in pounds) by your height (in centimeters) squared
Multiply that number by 73 = your BMI
a BMI of 25.0 to 29.9 is considered to be overweight
a BMI of 30 or more is considered to have obesity
That means, someone who stands 5’4” and weighs 175 pounds is considered to have obesity (BMI = 30), as is someone who stands 5’9”and weighs 204 pounds (BMI = 30.3).
Now, despite its ubiquity, BMI isn’t a perfect measure. Most notably, it doesn’t distinguish between fat and muscle, so a fit and muscular person and a sedentary person could share the same BMI. However, it is a good rough gauge of whether your body fat is in the healthy range.
When the American Medical Association officially recognized this in 2013, it was an important step forward educating millions of people, including health care providers, that obesity is not a personal choice or a character flaw. It’s a stubborn, difficult-to-treat condition with far-reaching health implications.
The Obesity Medicine Association put this succinctly: “For most people suffering with obesity, simply eating less and moving more will not result in sustainable long-term weight loss.”
How Do Obesity Medications Work?
Several anti-obesity medications (AOMs), sometimes known as weight loss pills, have been approved by the Food and Drug Administration for weight loss and chronic weight management. To qualify for a prescription, you need to have a BMI of 30 or greater.
Today’s AOMs reliably help people lose 3% to 10% or more of their total body weight. That may not seem like much, but it’s significant, because as a loss in this range, especially as you get towards 10 percent, is known to bring a bevy of health improvements, including a reduction in various heart-related risk factors; a reversal of sleep apnea, or even remission of type 2 diabetes.
Prescription AOMs work in several different ways. Some may make you feel less hungry; cause you to feel fuller, sooner; or may make food taste less appealing. Others can make it more difficult for the body to absorb fat or may ramp up your metabolism, causing you to burn more calories.
These medications aren’t as simple as popping a pill though—to be effective, they need to be coupled with lifestyle changes in the way you eat and how much you move. Your doctor will work with you to focus on several behavioral modifications that feel manageable with your lifestyle, and those will be combined with a specific medication.
Is Medication the First Step When Treating Obesity?
Not necessarily. Before moving to meds, your doctor will typically check that you’ve tried one or more lifestyle or behavioral modifications, such as improving your nutrition or ramping up your physical activity. These might include adopting a heart-healthy approach to eating like the Mediterranean diet, joining a program such as Weight Watchers, incorporating movement and exercise, food journaling…you get the idea.
Unfortunately, for those struggling with obesity, changes like these don’t tend to result in boatloads of success, weight loss-wise. Only about 5% of people will successfully treat their obesity using these lifestyle approaches, resulting in a lot of frustrating attempts.
In fact the average individual with obesity will wait six years before officially seeking medical help. During that time, they will likely try a wide array of strategies to shed weight, including diet, exercise, weight loss programs, and the like.
Anti-obesity medications of course need to be prescribed by a health care provider, so until an individual who’s suffering sees a doctor or other medical professional, they won’t have the chance to give any of them a try.
But some emerging research suggests that using an AOM early on in one’s weight loss journey may have impressive benefits. A small but intriguing study published in Obesity Science & Practice looked at people who, after living with obesity for varying amounts of time, had joined a weight loss program. Those who used an AOM before their eight-week mark in the weight-loss program lost more weight overall (an average of 14.2% vs. 10.8%) and were more likely to achieve 15% weight loss (45.1% vs. 19.0%) thank those who didn’t.
Here’s the 411 on the drugs most commonly used to treat obesity, including details regarding how they work, side effects to look out for, and which people might benefit the most from using them.
Qsymia (Phentermine + Topiramate ER)
If phentermine sounds familiar, it may be because it was one-half of fen-phen, the cult-status pill cocktail deemed the holy grail of weight loss in the ‘90s for its ability to kill appetite and dissolve the pounds away. Fenfluramine-phentermine ultimately ended up causing serious heart and lung problems in some patients and was taken off the market in 1997, but fenfluramine was deemed the problem, not phentermine, which has remained available.
A powerful stimulant, phentermine works by decreasing hunger and cravings. It can be prescribed alone, but many doctors prefer to use it in combination with topiramate, a migraine medication that helps to balance out some of the stimulating properties of phentermine, which otherwise might cause a rapid heart rate, high blood pressure, or insomnia. Interestingly, topiramate also makes most carbonated beverages taste metallic, so if a patient struggles with reducing soda intake, it can make for a nice fit.
Common side effects: Dry mouth, dizziness, insomnia, tingling in the hands and feet.
Contraindications: Pregnant women cannot take topiramate, as it can cause cleft palate. People with hyperthyroidism, glaucoma, or uncontrolled high blood pressure should also avoid it.
Out-of-pocket cost for 30 days: $98 to $240
Average weight loss at one year: Up to 14% of body weight
Especially helpful for: Patients with both migraines and obesity, as topiramate treats migraines.
Historically used to treat diabetes, Saxenda is now a go-to choice for many patients with obesity. That’s because the daily injectable drug, part of a class of medications called GLP-1 agonists, works in the appetite center of the brain, stepping on the gas pedal in terms of satiety and fullness and easing up on the hunger brake.
The needle you use for Saxenda is tiny and can be injected in the abdomen, thigh, or upper arm. Nausea can occur, so your doctor will likely start you with a low dose, gradually increasing it over the course of several weeks to avoid stomach upset.
There’s also a new generation of GLP-1 agonists on the horizon. One of them, semaglutide, is taken orally instead of being injected. The results are impressive: 40% of people taking it were found to lose more than 20 percent of their weight. Semaglutide is expected to be available by 2021.
Common side effects: Patients with type 2 diabetes may experience hypoglycemia (low blood sugar), headaches, back pain, fatigue, or a cough. Patients without type 2 diabetes may develop headaches, dizziness, fatigue, nausea, dry mouth, or constipation. If you have a history of pancreatitis, tell your doctor, as it’s necessary to proceed with caution to avoid complications
Contraindications: Personal or family history of medullary thyroid cancer (MTC) or multiple endocrine neoplasia type 2 (MEN2). Pregnant women and people with uncontrolled high blood pressure should avoid Saxenda.
Out-of-pocket cost for 30 days: About $1200
Average weight loss at one year: 9%
Especially helpful for: Patients with both type 2 diabetes and obesity, as Saxenda has historically been used to treat diabetes. Patients with pre-diabetes can benefit, too.
Contrave (Naltrexone + Bupropion)
Naltrexone and bupropion have both been used independently for years—bupropion is an antidepressant that also helps people quit smoking, and naltrexone helps those fighting alcohol and opioid dependence. Bupropion treats obesity by affecting the appetite center in the brain. (It’s worth mentioning that bupropion differs from many other antidepressants in that many of them are associated with weight gain.) Naltrexone is thought to help people resist food cravings, and may also to intensify bupropion’s appetite-dampening effects.
Like Saxenda, your doctor will likely start with a small dose, increasing gradually to avoid nausea.
Common side effects: Nausea, constipation, headache, dizziness, insomnia, dry mouth, diarrhea, vomiting.
Contraindications: Pregnant women and people with uncontrolled high blood pressure should not take Contrave, nor should people with a history of seizures, anorexia, or chronic opioid use or abuse.
Out-of-pocket cost for 30 days: $99 to $240
Average weight loss at one year: 8% of body weight
Especially helpful for: Patients with both depression and obesity, or smokers with obesity, as bupropion has antidepressant properties and is known to promote smoking cessation.
If you were in college in the ‘90s, you likely remember Olestra, a fat substitute used in cookies, chips, and other junk foods that left many users stuck on the toilet with diarrhea. Xenical works in a similar manner, blocking the absorption of about 30% of dietary fat, eliminating it through the stool. It’s taken up to three times a day, within an hour of beginning a meal.
Xenical is available in an over-the-counter version called Alli.
Common side effects: Fatty or oily stools, oily spotting, increased fecal urgency. They’re not pretty, but these same side effects can make Xenical a particularly effective drug because its side effects are often enough to dissuade patients from eating fast food and other high-fat foods.
Contraindications: Irritable Bowel Syndrome or other conditions that compromise nutrient absorption.
Out-of-pocket cost for 30 days: Up to $50
Average weight loss at one year: 3% of body weight
Especially helpful for: Patients who frequently experience constipation as well as who have obesity may appreciate this option, as it leads to increased fat in the stools, which can help get things moving.
Another AOM, Belviq (lorcaserin) was removed from the market in early 2020 due to an increased cancer risk.
Who Should I Talk to About Getting a Prescription?
Thinking an anti-obesity medications might be right for you? Your first step is to consult your primary care practitioner. Some may feel comfortable with prescribing and monitoring your progress, but not all will.
A more strategic step may be asking your doctor to refer you to an obesity medicine specialist. These experts have undergone additional training and are comfortable taking your weight and diet history, evaluating related medical and psychological issues you may be experiencing, and partnering with you to create an individualized obesity treatment plan, which may include an AOM.
Some insurance plans—perhaps even half of private insurers—will cover the cost of these medications, so be sure to check with yours. Medicaid and Medicare do not cover AOMs. In addition, some AOMs are available in generic form, making them more affordable.
Your doctor will ask you to return for a check-up around one month (to monitor your heart rate, blood pressure, and other vitals), and again at three months. In general, the goal with AOMs is to achieve 4% to 5% weight loss after three months at the full prescribing dose. If that hasn’t happened, it may be time to try another AOM.
Many people wonder whether they’ll need to be on an AOM forever. Obesity is much like many other diseases in that medication can help, but just because your condition improves doesn’t mean you no longer need medicine. AOMs help change your brain chemistry so you’re more apt to make healthy choices. Once you stop taking it, your old brain chemistry will resume and obesity may follow suit. For that reason, while a minority of patients will stop their meds, most stay on. Your doctor will help you chart out a long-term plan that works for you.
Frequently Asked QuestionsObesity Medication
Which medicine is best for obesity?
The answer to that depends on the person being treated. Your doctor will take several factors into consideration when choosing a medication to treat your obesity, including any comorbidities you may have; potential side effects of the medication and whether they will be well-tolerated; cost; and more. For instance, Qsymia (phentermine + topiramate ER) works by decreasing hunger and cravings, but individuals with hyperthyroidism, glaucoma, or uncontrolled high blood pressure should avoid it. At the same time, patients with migraines as well as obesity might do especially well on this drug, as Topiramate is an effective migraine medication.
What do you call a doctor who specializes in obesity?
An obesity medicine specialist is an expert who has undergone supplemental training in the field of obesity and its various treatments. This type of expert will take your weight and diet history; evaluate related medical and psychological issues you may be experiencing; and partner with you to create an individualized obesity treatment plan, which may include an anti-obesity medication (AOM).
Can you get anti-obesity medications from your doctor?
If you and your doctor decide that an AOM is right for you, he or she will prescribe the medication and ask you to return for a check-up around one month (to monitor your heart rate, blood pressure, and other vitals), and again at three months. Generally, the goal with AOMs is to achieve 4% to 5% weight loss after three months at the full prescribing dose. If that hasn’t happened, it may be time to try another AOM.
Are there hormonal medications that can make you lose weight?
You may be thinking of a class of medication called GLP-1 agonists, which work by mimicking a hormone that tells your brain your stomach is full. They’ve been described as stepping on the gas pedal in terms of fullness and satiety and pushing on the hunger brake. Saxenda (liraglutide) is an example of an injectable GLP-1 agonist. As with most drugs, side effects are possible; your physician will go over these with you when deciding if this drug is a good match for your obesity.
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