The best weight loss pills and medications

Contrary to what popular culture might teach you, you cannot identify obesity in yourself or others simply by observation–obesity is a chronic medical condition that affects millions of people worldwide. And while BMI is not the be-all and end-all assessment of obesity (it’s not without its problems), more than 73% of adults over the age of 20 have measurements in the overweight or obese range in the United States—that’s more than two out of every three adults. For some people, diet and exercise are not enough to lose weight and keep it off. Continue reading to learn more about weight loss medications that can help you lose weight and keep it off in a safe way. 

Historically, there are many different types of weight loss pills. And while there are still some weight loss pills on the market, it’s better to say weight loss medications or anti-obesity medications instead of pills, because the latest weight loss drugs that help people lose weight are not pills, but rather weekly or daily injections. These medications work in different ways, including

• Suppressing your appetite (decreasing your desire to eat) 

• Reducing how much fat you absorb from the foods you eat

• Making you feel full faster

Weight loss medications are not for everyone–people who are pregnant, trying to become pregnant, or breastfeeding should not use weight loss medication (but more on who is eligible for weight loss pills later). 

Most weight management medications are meant for adults over 18 years old with the following:

• Obesity with a BMI of 30 kg/m2 or more

• Overweight with a BMI of 27 kg/m2 or more with a weight-related health problem, like high blood pressure, type 2 diabetes, or heart disease

Wegovy (see Important Safety Information), a prescription weight loss medication (injection), is available to children over 12 years old with either: 

• Obesity: body mass index (BMI) of 30 kg/m² or greater 

• Overweight: BMI of 27 kg/m² or greater with at least one weight-related medical condition, such as type 2 diabetes, high blood pressure (hypertension), or high cholesterol

The easiest way to determine your weight category is to measure your Body Mass Index (BMI). BMI is a measurement of your body weight in kilograms (1 kilogram equals 2.2 pounds) divided by your height in meters squared (1 meter equals about 3 feet 3 inches). You can easily calculate your BMI by clicking here. Using your BMI, you can determine which of the following categories applies to you:

If your BMI is higher than 25, you have an increased risk of several health conditions, including heart disease, stroke, diabetes, and severe COVID-19. Losing as little as 5–10% of the excess weight can significantly improve your health. Weight loss medications, in addition to diet, exercise, and lifestyle modifications, are appropriate for some people to help with their weight loss goals. 

It’s important to keep in mind that BMI does not account for factors like sex, body composition, and more. Additionally, research to support BMI as an assessment tool lacks racial and ethnic diversity.

Unfortunately, there is no magic pill to cure obesity. However, GLP-1 receptor agonists, a class of drugs used to treat diabetes and manage weight, are proven to be highly effective weight management medications. GLP-1 agonists include:

• Tirzepatide (brand name Zepbound)

• Semaglutide (brand names Ozempic; see Important Safety Information, and Wegovy)

• Dulaglutide (brand name Trulicity)

• Liraglutide (brand names Saxenda and Victoza)

• Exenatide (brand names Bydureon and Byetta)

• Lixisenatide (brand name Adlyxin)

GLP-1 drugs work by mimicking the naturally-occurring hormone GLP-1, that you already have in your body. The hormone sends signals to your brain, letting it know when you are full, therefore decreasing your appetite and helping you to feel full faster. These weight loss medications also slow down the process of gastric emptying, when food inside the stomach moves into the small intestine during digestion.

In clinical trials, Wegovy (active ingredient semaglutide) helped adults with a BMI higher than 30 decrease their body weight by up to 15%. While weight loss results will vary based on the type of GLP-1 drug prescribed, dosage, and other lifestyle and health factors, they have been proven to be very effective at helping people lose weight and maintain weight loss.

How long you need to continue to take your weight loss medication depends on several factors and will vary from person to person. Depending on the side effects you experience and the success of your weight loss, your healthcare provider may need to adjust your dosage. Unfortunately, this means you might experience a trial-and-error period before seeing results. 

If your weight loss is successful and you don’t experience negative side effects, your healthcare provider may recommend taking your weight loss medication long-term to help you keep the weight off. If you take your medication as prescribed and aren’t seeing results, your healthcare provider may prescribe you a different weight loss pill.

That said, the Food and Drug Administration (FDA) has approved certain weight loss medications for short-term and long-term use. Continue reading to learn more.

Short-term weight loss pills

The FDA has approved four medications for short-term use (up to 12 weeks) to help achieve weight loss: 

• Phentermine

• Benzphetamine

• Diethylpropion

• Phendimetrazine

These drugs are all stimulants that decrease your appetite so that you eat less. Some of these medications are Schedule IV, meaning they have a higher potential for drug abuse. Potential side effects of these short-term weight loss pills include increased heart rate, high blood pressure, trouble sleeping (insomnia), dry mouth, constipation, and nervousness.

People with heart disease, poorly controlled high blood pressure, or a history of addiction or drug abuse should not use these medications. Never take weight loss pills if you are pregnant or breastfeeding. 

Long-term weight loss pills and medications

Given all of the risks of the short-term weight-loss drugs, most healthcare providers turn to treatments approved for longer time frames. There are currently five medications approved by the FDA for the long-term treatment of weight loss:

• Phentermine/topiramate (Qsymia)

• Liraglutide (Saxenda)

• Semaglutide (Wegovy)

• Naltrexone/bupropion (Contrave)

• Orlistat (Xenical, Alli) 

These five drugs are all considered effective at helping people achieve at least 5% weight loss after using them for one year.  

Lorcaserin (brand name Belviq), a previously approved weight loss drug, has recently been withdrawn from the U.S. market. The FDA asked the manufacturing company, Eisai Inc., to voluntarily recall lorcaserin because of an increased cancer occurrence.

Continue reading to learn more about specific weight loss pills. 

All new prescription drugs have to be tested in clinical trials to ensure they’re safe and effective for whatever condition they treat. The US Food and Drug Administration, or FDA, reviews the clinical trial data and determines whether a drug is “approved” for a particular use. The FDA also establishes specific guidelines for a medication’s use. This is a complex process that often takes years, but once a drug is approved for a specific condition, its use is then considered on-label. 

Semaglutide is a GLP-1 agonist and injectable drug used to treat diabetes and obesity. While there is an oral pill, only the injectable form is FDA-approved to treat obesity. As mentioned, semaglutide is extremely effective for weight management. Clinical trials showed that Wegovy was able to help adults with a BMI higher than 30 decrease their body weight by up to 15%. This drug also helped improve blood pressure and cholesterol measurements.

Common side effects include mild to moderate nausea, vomiting, diarrhea, and constipation, which are usually temporary. As with any medication used to treat diabetes, low blood sugar is a potential side effect.

Ro’s Body Program will connect you to a US-licensed healthcare professional who can discuss whether using a medication like Wegovy to lose weight is right for you. 

Liraglutide, like semaglutide, is a GLP-1 agonist, used to treat type 2 diabetes and obesity. Liraglutide affects how fast your stomach empties and the hormonal changes that occur after eating. The end result? You feel less hungry and eat less. Another benefit is that people with diabetes and cardiovascular disease have fewer heart attacks and strokes when taking liraglutide compared to placebo.  

Common side effects include nausea, vomiting, diarrhea, and sometimes low blood sugar, especially when combined with other diabetes medications. In rare cases, it can increase your risk of pancreatitis, an inflammation of the pancreas. Lastly, animal studies have shown that it may increase the risk of thyroid tumors—so far, clinical trials have not demonstrated an increase in thyroid tumors. However, people with a history of pancreatitis or thyroid tumors should avoid this medication.

Naltrexone treats drug and alcohol dependence, while bupropion (see Important Safety Information) can improve depression and help people quit smoking. The combination of these two medications may affect dopamine, a brain chemical. By doing so, this drug reduces food cravings and decreases your appetite.

Common side effects of naltrexone/bupropion include nausea, headaches, constipation, insomnia, vomiting, dizziness, and dry mouth. Some people also notice elevations in blood pressure and heart rate while using naltrexone/bupropion. Since this combo medication includes bupropion, an antidepressant, it may increase the risk of suicide in young adults with depression when they first start treatment (a known side effect of antidepressants). 

People with uncontrolled high blood pressure, seizure disorders, eating disorders, chronic opioid use, and severe liver failure should avoid using this drug. Also, anyone who has used monoamine oxidase inhibitors (MAOIs) in the past 14 days should not take naltrexone/bupropion because of the risk of serious side effects and drug interactions. 

Phentermine/topiramate is a combination of phentermine and the anti-seizure drug topiramate; using both drugs together works better than either drug alone to reduce appetite. Because of the potential for abuse, the DEA considers it a scheduled drug. You should avoid using phentermine/topiramate if you have high blood pressure or coronary heart disease. Side effects include dry mouth, constipation, paraesthesias (numbness/tingling), depression, anxiety, and elevated heart rate.

Orlistat works by decreasing the absorption of fats from your food—it reduces fat absorption by up to 30%. Orlistat is available in prescription strength (brand name Xenical) and a lower strength over-the-counter formulation (brand name Alli). 

Most of the side effects of orlistat affect your gastrointestinal (GI) system, including stomach rumbling, abdominal cramps, bloating, and constipation. Some of the more distressing GI effects include:

• Passing gas (sometimes with oily spotting)

• Diarrhea, loose stools, or greasy stools

• Frequent bowel movements that are hard to control

• Liver damage (rare effect)

Fortunately, most of these issues improve after using it for a while. Also, you can avoid some of them by sticking to a low-fat diet. Other side effects include poor absorption of fat-soluble vitamins (vitamins A, D, E, and K) and kidney stones.

The drugs mentioned above are the ones that carry FDA approval. However, other drugs may be used “off-label” to help with weight loss. Off-label simply means that a drug is being used for a condition that it was not originally approved to treat. 

Take the GLP-1 agonists for example. Most of the drugs in that class are FDA-approved to treat diabetes, with only Wegovy and Saxenda FDA-approved for weight loss. However, many of the other medications in that group are linked to weight loss in people using them to improve their diabetes. Other blood-sugar-lowering medications like metformin and pramlintide may also help people with diabetes lose weight. 

Antidepressants, drugs used to treat depression, are another class of medications that may help people lose weight. Bupropion, one of the drugs in the FDA-approved weight loss medicine Contrave, is an antidepressant that may aid weight loss.

Other options are available if prescription weight loss medications aren’t right for you.

Plenity

Plenity is an FDA-cleared weight management tool that can help you drop body weight. It’s a pill that once swallowed, turns into a gel in your stomach. Plenity works by taking up room in your stomach, helping you feel fuller after eating less food (and fewer calories) thereby aiding weight loss. Studies suggest that people who take Plenity are twice as likely to lose 5–10% of their body weight than those taking a placebo. 

Most of the side effects from Plenity are mild and include diarrhea, bloating, changes in bowel movement frequency, gas, constipation, nausea, and abdominal pain.

Weight loss surgery

While surgery is the most invasive form of weight management, many of these procedures have been shown to help with weight loss, including:

• Gastric banding: an inflatable band is placed around the stomach to create a smaller pouch, effectively reducing how much food you can eat and makes you feel fuller faster

• Sleeve gastrectomy: most of your stomach is removed in this procedure, leaving you with a smaller stomach that it takes less food to feel full. It has the added benefit of affecting the gut hormones that play a role in hunger, feeling full, and blood sugar control.

• Gastric bypass: also called Roux-en-Y gastric bypass, is a complicated surgery that reduces the size of your stomach and rearranges the small intestine to decrease calorie absorption. It can also affect your gut hormones.

Weight loss surgery is an effective option to manage your weight, but it does come with a risk of side effects and potential complications, such as nausea, vomiting, heartburn, abdominal pain, and infections. Some of these procedures can increase your risk for nutrient deficiencies like vitamin B12, iron, and folate deficiencies. 

Unfortunately, weight loss medications only work as long as you take them— when you stop them, you will likely gain weight back. That’s why it is so important to incorporate diet and exercise changes into your daily routine. 

As much as we may wish, weight loss pills and injectable weight loss drugs like Wegovy shouldn’t replace diet and exercise. Weight loss drugs should be part of a comprehensive treatment plan that includes lifestyle modifications, like diet and exercise, counseling, and behavioral interventions. Adding lifestyle changes may also help you minimize weight regain once you stop the weight loss pills.

People taking weight loss medications along with lifestyle modifications lose, on average, 7–10% of their initial weight after one year. These compounding effects may improve your risk of multiple health problems like type 2 diabetes and high blood pressure. 

Weight loss medications may be the added boost you need to help you lose weight. However, they’re not for everyone. Talk to your healthcare provider about prescription medications for weight management to determine if any are right for you. 

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How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

June 23, 2023

Written by

Chimene Richa, MD

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.