Do appetite suppressants work?

Appetite suppressants may help some people reduce hunger and support weight loss, but how well they work depends on the medication and the person. Their safety is unknown. Prescription options are approved by the US Food and Drug Administration (FDA) and backed by clinical trials, while over-the-counter supplements have limited research behind them. 

Below, learn about the types of appetite suppressants available, their side effects, and who they may be right for.

A systematic review and meta-analysis of five weight loss medications found that 44%–75% of adults with overweight or obesity lost at least 5% of their body weight after one year, compared with 23% of adults who took a placebo. 

In this older study, phentermine-topiramate and liraglutide were associated with the highest odds of losing at least 5%. Lifestyle changes, such as consistent physical activity and a healthy diet, are typically recommended alongside medications to help keep the weight off long term.

Newer GLP-1 medications, such as Wegovy (semaglutide) and Zepbound (tirzepatide), have produced larger average weight loss in more recent clinical trials. In one clinical trial, adults with obesity or overweight who took tirzepatide lost an average of 15%–21% of their body weight over 72 weeks, depending on the dose. Across doses, 85%–91% of participants who took tirzepatide lost at least 5% of their body weight, compared with 35% of those who took a placebo. The most common side effects were gastrointestinal, and most were mild to moderate.

See if you qualify

Several types of appetite suppressants are available, including short-term and long-term prescription medications and natural options. Which one may be appropriate depends on a person's health, medical history, and weight management goals.

Prescription appetite suppressants

The FDA has approved several prescription medications designed to help reduce appetite. Some are approved for long-term use, while others are meant to be taken for a short time. 

These medications work in different ways. Phentermine, for example, acts on the central nervous system to reduce appetite, while GLP-1 medications mimic a natural hormone that helps regulate hunger and fullness.

Short-term appetite suppressants approved by the FDA include:

• Phentermine (Adipex-P, Lomaira)

• Benzphetamine (Didrex, Regimex)

• Phendimetrazine (Bontril PDM)

• Diethylpropion

Long-term options for weight loss include:

• Phentermine-topiramate (Qsymia)

• Naltrexone-bupropion (Contrave)

• Semaglutide (Wegovy and Wegovy pill)

• Liraglutide (Saxenda)

• Tirzepatide (Zepbound)

• Orforglipron (Foundayo)

Other weight loss medications, such as orlistat (Xenical, Alli), work by reducing fat absorption in the digestive system rather than by suppressing appetite.

Natural appetite suppressants

Some dietary supplements claim to suppress appetite naturally, without medication. More research is needed, and the evidence for the options below varies. These substances are not regulated the same way as prescription medications so be sure to obtain them from trusted sources. In some cases, supplements have been associated with liver injury.

1. Green tea extract

Green tea has long been touted as a weight loss aid, but the evidence that green tea specifically helps with weight loss isn't very strong. Drinking a cup or two a day is one option, but green tea supplements are not FDA-approved for weight loss. 

2. Garcinia cambogia 

This fruit grows naturally in India and other parts of South Asia. It contains a chemical similar to citric acid called hydroxycitric acid, which people claim can decrease appetite and help with weight loss, though its potential weight loss benefits have not been well proven in clinical trials. 

3. Glucomannan 

This fiber comes from the Amorphophallus konjac plant. Because glucomannan can absorb 50 times its weight in water, research suggests it may fill the stomach and help people feel full. Because glucomannan swells quickly, if you choose to take it be sure to take it with a full glass of water to avoid choking or blockage. Don’t lie down immediately after taking it. If you have issues with swallowing you may want to avoid it altogether. 

4. Capsaicin

There are claims that capsaicin — a compound found in chili peppers such as cayenne — can help with everything from lowering high blood sugar to weight loss.

Research suggests that capsaicin may help reduce appetite by promoting a feeling of fullness, but that doesn't mean eating large amounts of hot peppers is a good idea. One small study of a combination of capsaicin, ginger, and green tea extracts found slightly greater weight loss among participants who took the supplements than among those who took a placebo.

5. Yerba mate 

This plant is native to subtropical areas, especially in South America, where many people use its leaves to make beverages. Studies in mice have shown positive weight loss results, but research in humans is limited.

6. Dietary fiber 

Foods high in fiber — such as fruit, vegetables, oats, and legumes — slow the absorption and digestion of carbohydrates and help you feel fuller for longer, which may aid in weight management.

Cutting back on sugar may also help. Sugary foods and drinks tend to be less filling than other foods, which may lead people to eat more overall. 

The FDA has not approved any over-the-counter weight loss or appetite suppressant supplements. More research is needed to understand how safe and effective these supplements are.

If you're interested in weight loss support, a healthcare provider can help you develop a care plan to reach your goals safely. A Ro-affiliated healthcare provider can also talk with you about whether prescription weight loss medications may be appropriate.

Weight loss medications are usually prescribed to people with a body mass index (BMI) of at least 30.

BMI is commonly used by healthcare providers and researchers to estimate body fat, but the calculation isn't always accurate. BMI has been criticized for not taking body fat distribution, sex, or ethnicity into account. A healthcare provider can help determine whether these medications are right for you.

A healthcare provider may also prescribe one of these medications to people with a BMI of 27 or higher who have a condition associated with excess body weight, such as type 2 diabetes, high cholesterol, or obstructive sleep apnea.

Appetite suppressants may interact with certain medications, including some antidepressants. People with certain health conditions, or who take certain medications, may need to avoid appetite suppressants or use them with caution. Examples include:

• Glaucoma

• Heart disease

• History of drug misuse

• Hyperthyroidism (overactive thyroid)

• Liver disease

• Pregnancy or breastfeeding

• Current or recent use of a monoamine oxidase inhibitor (MAOI), a type of antidepressant

• Seizures

• Eating disorders

Certain medications may not be suitable for those with a personal or family history of medullary thyroid cancer. 

Because appetite suppressants carry different risks, talk with a healthcare provider about all your medical conditions and medications before starting one. In general, prescription medication may be a better option than non-prescription appetite suppressants due to better regulation by the FDA. 

Side effects of appetite suppressants vary depending on the medication or supplement at hand. 

Common side effects

Common side effects of prescription appetite suppressants may include:

• Increased blood pressure

• Trouble sleeping (insomnia)

• Headache

• Nervousness

• Constipation

• Dry mouth

• Nausea, vomiting, or diarrhea

For some people, these side effects ease with continued use, though that varies by medication and person.

Serious side effects

Serious side effects can occur with some appetite suppressants, though the risks vary by medication. People who experience serious side effects, such as those in the phentermine prescribing information or the prescribing information of other weight loss medications, should get medical help right away. Examples include:

• Heart problems: rapid or irregular heartbeat and high blood pressure

• Severe mood changes: depression, paranoia, delusions

• Pancreatitis: severe, persistent abdominal pain

• Dependence and misuse: physical dependence or misuse of the medication

Start your journey

Appetite suppressants may help reduce hunger and support weight loss, but results vary by medication and person. Here's what to know if you're considering one:

• Appetite suppressants come in several types, including short-term and long-term prescription medications and natural supplements.

• Healthcare providers may recommend a prescription appetite suppressant for people with a BMI of 30 or higher, or 27 or higher with a weight-related condition. They aren't right for everyone, though, and people who take certain medications or have certain medical conditions may need to avoid them altogether.

• Appetite suppressants may cause side effects, from common ones such as dry mouth and trouble sleeping to serious risks such as heart problems, and the risks vary by medication.

A healthcare provider can help weigh the potential benefits and risks of any appetite suppressant based on a person's health history, current medications, and goals.