Appetite suppressants: how they work, side effects, and natural alternatives

Appetite suppressants are weight loss medications that make you feel full. Researchers think these medications work by affecting the appetite control and reward centers of the brain (Sombra, 2020). There are both prescription and over-the-counter options available, but not all treatments are created equal. Even the most effective treatments aren’t right for everyone.

Diet, exercise, and other healthy lifestyle choices are the most effective ways to lose weight and keep it off. Getting started can be difficult, though, so a healthcare provider may prescribe appetite suppressants to help people get a jumpstart on their weight loss journey.

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Types of appetite suppressants

The U.S. Food and Drug Administration (FDA) has approved several prescription medications designed to suppress your appetite. Some are approved for long-term use, while others are meant to be taken for a short time, usually less than 12 weeks. 

Short-term appetite suppressants authorized by the FDA include:

• Phentermine (brand names Adipex P, Lomaira)

• Benzphetamine (brand names Didrex, Regimex) 

• Phendimetrazine (brand name Bontril PDM) 

• Diethylpropion

• Naltrexone-bupropion (brand name Contrave)

Long-term options for diet pills include:

• Phentermine-topiramate (brand name Qsymia) 

• Semaglutide (brand name Wegovy)

There are other options for weight loss that don’t suppress your appetite. These include the medication orlistat (sold under the brand names Xenical or Alli). Although this medication has been proven to help lose weight, it works by preventing fat absorption in your digestive system rather than by suppressing appetite.

Who may benefit from an appetite suppressant?

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

While BMI is classically used by healthcare providers and researchers to estimate your body fat percentage, the calculation isn’t always accurate. Your healthcare provider will help decide if these treatments are right for you.

You may receive a prescription for one of these medications if you have a condition associated with excess body weight, such as type 2 diabetes, heart disease, or obstructive sleep apnea. 

Do appetite suppressants work?

Research shows that weight loss drugs can help you shed pounds, but they aren’t a magic cure. 

People who take these drugs lose around 10 to 25 more pounds of body weight compared to those who don’t (Bersoux, 2017).

The key is taking weight loss drugs is ensuring it's part of a broader program that includes a healthy diet, exercise, and other lifestyle changes. Since most of these treatments are not intended for long-term use, lifestyle changes are crucial to keeping weight off in the long run.

Although there are many benefits of appetite suppressants, they don’t work for everyone. You may also hit a plateau after losing weight, and when you stop taking appetite suppressants, you’ll likely gain weight back (Sombra, 2020).

Side effects of appetite suppressants

Side effects of weight loss medications vary depending on the medication. Common side effects may include (Bersoux, 2017):

• Increased blood pressure

• Trouble sleeping (insomnia)

• Headache

• Nervousness

• Nausea

• Constipation

• Dry mouth

• Depression

Natural appetite suppressants

Some dietary supplements claim to suppress your appetite naturally––without medication. Here are some natural substances that could quash your hunger:

Green tea extract: There are some who tout the benefits of green tea as a weight loss tool. While drinking more liquids can help you lose weight (enter green tea), the evidence that it’s specifically doing the heavy lifting isn’t very strong. Your best bet is to drink a cup of tea or two, but skip pills and potions that claim to contain it. (Sombra, 2020).

Garcinia cambogia This fruit naturally grows in India and other parts of South Asia. It contains a chemical similar to citric acid called hydroxycitric acid (AHC), which may decrease appetite and help with weight control (Maia-Landim, 2018).

Glucomannan: This fiber is taken from the Amorphophallus konjacplant. Since glucomannan can absorb 50 times its weight in water, researchers suggest that it can fill up your stomach and make you feel full (Maia-Landim, 2018).

Capsaicin: There are some claims that capsaicin, a fiery derivative of cayenne peppers, can help with everything from reducing high blood sugar to weight loss. Some claim that capsaicin helps reduce your appetite by helping you feel full (Zheng, 2017). But that doesn’t mean you should be shoveling down fistfuls of hot peppers. One small study looking at the use of a combo supplement containing capsaicin, ginger, and green tea extracts showed a slight increase in weight loss among participants who used these treatments when compared to placebo (Taghizadeh, 2017).

Yerba mate: This plant is native to subtropical areas, especially South America. Many people in this part of the world use its leaves to make beverages. While not proven in humans yet, studies in mice show positive weight loss results (Gamboa-Gómez, 2015).

Dietary fiber: Foods high in fiber––like fruit, vegetables, oats, and legumes––slow the absorption and digestion of carbohydrates and help you to feel fuller for longer, which can aid in weight management (Akbar, 2021).

Skip the sugar: It won't hold your hunger in check, but too much sugar does boost your appetite. Sugar spikes trigger hormone release from your pancreas, which can make you feel hungrier (Hantzidiamantis, 2020).

Keep in mind that the FDA has not given the green light to any over-the-counter weight loss or appetite suppressant supplements. Researchers haven’t tested or reviewed them in-depth to prove they’re safe and work as they should (Tirthani, 2021).

Talk to a healthcare provider to find out if a prescription appetite suppressant is 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

August 19, 2021

Written by

Alyson Powell Key

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.