Struggling to lose weight despite diet and lifestyle changes? You may be wondering if prescription medications are right for you. We break down everything you need to know.
Losing weight and keeping it off long-term is no easy feat. In fact, over 80% of people who successfully lose weight end up regaining it within a year.
If you feel like you’ve tried just about everything to slim down unsuccessfully, prescription weight loss medications may seem appealing. But are they safe? And would using one actually help you lose weight?
To find out, we analyzed all of the prescription weight loss pills currently available, how they work, who they might be suitable for, effectiveness data, and potential side effects.
Here’s what to know.
An Overview of Prescription Weight Loss Medications
The Food and Drug Administration (FDA) has greenlit several prescription medications for losing weight in people with obesity or who are overweight with weight-related health conditions.
These include:
- GLP-1 receptor agonists – liraglutide (Saxenda), semaglutide (Wegovy), tirzepatide (Mounjaro)
- Orlistat (Xenical)
- Phentermine/topiramate (Qsymia)
- Naltrexone/bupropion (Contrave)
- Setmelanotide (Imcivree) for genetic disorders
- Appetite suppressants like phentermine (Adipex-P, Lomaira)
Most weight loss medications should be combined with lifestyle changes like healthy eating and regular physical activity for the best and most sustainable results.
How Do Prescription Weight Loss Medications Work?
Prescription weight loss medications promote weight loss through one or more of the following mechanisms:
- Decreasing appetite and hunger
- Increasing feelings of fullness
- Limiting how many calories get absorbed from food
- Boosting metabolism and fat-burning
For example, the drug orlistat works by blocking the digestion and absorption of dietary fats.
On the other hand, phentermine is an appetite suppressant that alters neurotransmitter levels in the brain to reduce hunger.
Meanwhile, medications like Wegovy (semaglutide) make you feel fuller faster so you eat less overall.
How Effective Are Prescription Weight Loss Pills?
Clinical trials show prescription weight loss medications can be fairly effective for weight loss when combined with lifestyle interventions. Results vary depending on the specific drug.
According to research, people taking prescription weight loss medications tend to lose anywhere from 5% to upwards of 15% of their body weight over 6 months to 1 year.
For instance, those taking Wegovy lost nearly 15% of their initial body weight after 68 weeks in one study. And in another trial, participants on Saxenda dropped roughly 8 kg (17 pounds) over 6 months.
However, everyone responds differently to these drugs. Some people lose more weight than average while others lose less. Weight loss also slows down over time.
To keep weight off long-term, adopting healthy lifestyle behaviors is key. Medications alone often lead to weight regain after discontinuation.
Who Are Prescription Weight Loss Medications For?
Prescription weight loss pills are designed for adults struggling with obesity or who have excess weight and a BMI over 27 plus an obesity-related condition. This includes type 2 diabetes, heart disease, or high blood pressure.
Per FDA guidelines, candidates should have first attempted to lose weight through diet, exercise, and behavior changes without success. These medications are meant to complement lifestyle interventions.
Pregnant and breastfeeding women should not take weight loss medications due to limited safety data. The same applies to those with certain medical conditions or taking medications that could interact with these drugs.
A doctor can help determine if prescription weight loss pills are appropriate for you based on health status, weight loss goals, and medical history.
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Types of Prescription Weight Loss Medications Available
1. GLP-1 Receptor Agonists
GLP-1 receptor agonists like Saxenda, Wegovy, and Ozempic are newer diabetes drugs now approved for weight management. They’re self-injected 1x/week.
How they work: GLP-1 drugs mimic the effects of GLP-1, a hunger-reducing hormone. As a result, they suppress appetite, slow stomach emptying, and promote weight loss.
Effectiveness: In trials, GLP-1 medications resulted in average weight loss ranging from 5% for Ozempic to 15% for Wegovy relative to placebo groups not using these drugs.
Side effects: Nausea, diarrhea, vomiting, constipation. May also increase heart rate. Gallbladder disease and suicidal ideation are rare but serious risks to monitor for.
2. Orlistat (Xenical)
Unlike other weight loss medications that reduce appetite, the prescription drug Xenical prevents the absorption of dietary fats to minimize calorie intake from meals.
How it works: Orlistat blocks enzymes needed to digest and break down fats. Undigested fats can’t be absorbed and are excreted in stool.
Effectiveness: In one trial, participants lost an average of 4.65 kg (10 pounds) while taking Xenical over 6 months. Belly fat, BMI, cholesterol, triglycerides, and blood glucose also decreased.
Side effects: Oily spotting, loose stools, frequent bowel movements, flatulence, urgent bowel movements. May also impair absorption of fat-soluble vitamins A, D, E and K.
3. Phentermine/Topiramate (Qsymia)
Qsymia combines phentermine, an appetite suppressant, together with topiramate, an anticonvulsant medication originally developed for epilepsy. It comes as an oral capsule taken once daily.
How it works: Phentermine reduces hunger by increasing neurotransmitter levels in the brain. Topiramate is believed to boost phentermine’s effects through several mechanisms, including reducing appetite and enhancing feelings of fullness.
Effectiveness: In trials, participants lost an average of 5% to upwards of 10% of their body weight on the phentermine/topiramate combo pill Qsymia.
Side effects: Tingling in hands and feet, dizziness, changes in taste, insomnia, constipation, dry mouth. Rare but serious side effects may include increased body temperature and heart rate.
4. Naltrexone/Bupropion (Contrave)
Contrave contains two generic medications: naltrexone, used to treat alcohol and opioid addiction, and bupropion, an antidepressant medication that promotes weight loss.
How it works: Thought to reduce appetite and food cravings. May also alter metabolism in the brain to enhance weight loss.
Effectiveness: In one analysis, people taking Contrave lost 5% to 9% of body weight after 56 weeks compared to groups not taking this medication.
Side effects: The most common side effects are nausea, constipation, headaches, vomiting, and dizziness. May also raise blood pressure and heart rate.
The Skinny on Weight Loss Medications: The Good, Bad and Who It’s For
Prescription weight loss drugs offer both pros and cons compared to natural weight loss methods. We break these down so you can make an informed decision with your provider.
Potential Benefits of Weight Loss Medications
When combined with healthy lifestyle changes, FDA-approved prescription weight loss drugs:
- Produce significant weight loss for many people struggling to slim down when diet and exercise alone haven’t worked
- Result in 5-15% weight loss on average
- May provide other health benefits like lower blood sugar, cholesterol, triglycerides or blood pressure
- Are more accessible than ever thanks to telehealth weight loss providers
Downsides of Prescription Weight Loss Pills
However, there are some key downsides of weight loss medications to consider:
- Can be expensive depending on insurance coverage
- Some have unpleasant or intolerable side effects
- Limited data on long-term efficacy and safety
- Don’t address underlying habits leading to weight gain
- Weight regain is common after stopping medication
In most cases, prescription weight loss drugs are reserved for those with:
- Obesity (BMI 30+) or overweight (BMI 27+) plus an obesity-related condition like heart disease or type 2 diabetes
- Inability to lose weight through sustained lifestyle interventions like diet and exercise
- No contradictions or safety concerns ruling out medication use
Prescription weight loss pills are tools that complement a comprehensive weight loss plan focused on sustainable habit change. Working with an obesity medicine specialist or registered dietitian can help ensure medication success.
The Bottom Line: Who Should and Shouldn’t Take Prescription Weight Loss Medications
If you have obesity and have struggled unsuccessfully to lose weight through both diet and exercise, weight loss medications under medical supervision may help augment your progress.
However, these drugs aren’t for everyone. You should avoid prescription weight loss pills if you are pregnant, have certain medical conditions, or take contraindicated medications. Kids under 12 should not take weight loss medications due to limited safety data.
Talk to your primary care doctor or endocrinologist to see if prescription weight loss medications are appropriate for you based on your BMI, health history and weight loss difficulties.