FDA Approved Weight Loss Medications & How They Work

16 Feb FDA Approved Weight Loss Medications & How They Work

Over 75% of Americans are overweight with over 30% obese; therefore, weight loss solutions are imperative. A bariatrician is a medical doctor who treats patients with excess fat and diseases related to extra weight such as high blood pressure and joint pain. In addition to nutrition, physical activity, and behavioral health, a bariatrician often uses FDA approved weight loss medications as a treatment for obesity. Obesity is not only the most common medical condition that adult patients share but it is also linked to deadly diseases such as heart disease, fatty liver, and various cancers. Unfortunately, obesity is severely under treated and as a result many individuals resort to ineffective or dangerous methods for weight loss.

In most cases if a doctor prescribes one of these medications for weight loss it is because the risk of overweight or obesity outweighs the risk of the medication.

This article discusses safe and effective FDA approved weight loss medications and how they work.

Why FDA Approval Matters

The Federal Drug Administration (FDA) is a government agency that regulates medications prescribed in the United States for safety and efficacy (or effectiveness). All medications have side effects; however, drugs approved by the FDA are studied for several years in volunteer patients to determine how they work and the most common side effects. Several medications require additional testing even after FDA approval. FDA approved weight loss medications must demonstrate more weight loss when compared to diet and exercise alone and/or a placebo. On the contrary, non-FDA approved substances have not been tested under strict regulatory guidelines and have not been required to show superior results to placebo or diet and exercise alone.

How Much Weight Will You Lose?

The amount and rate of weight loss depends on the medication, the starting weight, the individual, and how well one follows proper nutrition and physical activity recommendations. On average, weight loss medications will yield twice the amount of weight loss when compared to placebo and diet and exercise alone. In the case of “resistant weight loss” sometimes a weight loss medication is the only way people are able to successfully lose weight despite their best efforts. The amount of weight loss can range anywhere from 20-40 pounds to over  100 pounds and depends on the amount of excess fat on the body. In addition, weight loss medication can be used after bariatric surgery for patients who experience weight regain.

What is the criteria for weight loss medication?

In order to qualify for a weight loss medication, you must have a Body Mass Index (BMI) greater than 30 or a BMI greater than 27 (overweight category) with at least 1 weight related co-morbidity (such as sleep apnea, joint pain, or diabetes).

The BMI is the ratio of weight to height and can be over-estimated for individuals with a lot of muscle mass or underestimated for individuals with a low body weight and high body fat percent (since it does not account for body composition). You can calculate your BMI using our BMI Calculator on the bottom right corner of the website’s home page.

FDA Approved Weight Loss Medications

#1 Phentermine – Adipex, Suprenza, Lomaira

 Phentermine is the #1 prescribed weight loss medicine in the United States and was first approved in 1959. Phentermine is popular for it’s appetite suppression and energy producing effects that lead to weight loss. Phentermine comes in the form of a tablet, capsule, or disintegrating pill (Suprenza) and works by releasing norepinephrine; a brain chemical that can reduce food intake, increase energy and metabolism, and break down fat. The medication is taken in the morning because it can cause insomnia or difficulty sleeping. The most common side effect is thirst from dry mouth; however, phentermine can also cause feelings of nervousness, increased heart rate, heart palpitations, increased blood pressure, chest pain, headache, and dizziness.

Phentermine is not safe for everyone, especially those with a history of heart disease, therefore, a prescription from a doctor is required along with routine monitoring.

Lomaira is a special formulation of phentermine in a low dose. It may be better tolerated due to the smaller dosage and can be taken up to 3 times a day.

 Check out Dr Covington’s Youtube Videos on Phentermine 

Phentermine and How it Works

Most Common Mistakes People Make with Phentermine

#2 Qsymia (phentermine and topiramate)

Qsymia was FDA approved in 2012 and is the combination of two medications that both impact weight loss separately. Phentermine is an appetite suppressant while topiramate aids in binge eating and cravings; the combination of these two medicines enhances weight loss results. Topiramate is also used to treat seizure disorder and migraine. In clinical studies, Qsymia demonstrated an average weight loss of 8.5% when compared to placebo, with almost half of the patients losing more than 10% in the first few weeks.  Qsymia should not be taken by pregnant women or women seeking to get pregnant (this is common for all weight loss medications) and can cause dizziness, constipation, numbness, unusual taste, dry mouth, difficulty sleeping, and changes in mood. Women of childbearing age are strongly recommended to take a monthly pregnancy test and use birth control or barrier protection when taking this medication.

Check out Dr Covington’s Youtube Video discussing Qsymia and How it Works

#3 Belviq and Belviq XR (lorcaserin)

Belviq is a weight loss medication approved in 2012 that causes a release of serotonin in the brain. Belviq comes in 2 forms, one is immediate release that is taken twice a day and the other is extended release and can be taken once a day. Belviq works by reducing appetite, hunger, and cravings along with the ability to get full quicker with less food. Common side effects are dizziness, headache, fatigue, constipation, diarrhea, nausea, and dry mouth. Belviq may also benefit patients with obesity and diabetes as it demonstrates an independent ability to reduce hemoglobin A1c, a lab value used to determine the severity of diabetes.

 #4. Contrave (naltrexone and bupropion)

This weight loss pill is comprised of two previously approved drugs, naltrexone and bupropion. Buproprion is used for depression and smoking and has been shown to reduce hunger and aid in weight loss. Naltrexone is used for alcohol cessation but enhances the effect of bupropion by adding to the reduction in hunger and cravings. Contrave was approved in the United States in 2014. Clinical trials demonstrate that close to 50% of patients lost at least 5% of their excess weight when compared to placebo. Like Qsymia, Contrave follows a weekly titration until reaching the target weight loss dose. Contrave can increase heart rate (2-3 beat per minute) and cause constipation and diarrhea, headache, dizziness, insomnia, nausea, vomiting, and dry mouth, and should not be used in anyone with a history of seizures of liver disease.

#5. Saxenda (liraglutide)

 Saxenda, approved in 2014, is unique from the other weight loss medications in that it is an injection of a “biologic” that must be refrigerated, whereas the other weight loss medications are pills. Saxenda is a glucagon-like peptide-1 (GLP-1) product which means it is a satiety hormone that is already produced in the body. Saxenda works by enhancing satiety and helps individuals feel full and eat less calories. The medication is injected once a day in the abdomen, arm, or thigh and is titrated up over a 5-week period until the top dose is reached. The most common side effect is nausea but can also cause headache, diarrhea, constipation, abdominal pain, and an increase in heart rate.

 #5. Orlistat (Xenical, Alli)

 Orlistat is approved for weight loss and works by reducing the absorption of fat from food. The medication comes in 2 versions, one is Xenical which requires a prescription and the other is Alli (a lower dose) that is available over the counter. The medication can reduce dietary fat absorption by as much as 25%. Orlistat is the only weight loss medication approved for use in children.  The most common side effects are stomach pain and loose stools which can occur with a fatty meal; therefore, patients are advised to eat a low-fat diet to reduce this effect.

#6. Diethylpropion, Benzphetamine, and Phendimetrazine (Bontril)

 These medications are appetite suppressants that work similarly to phentermine but may be tolerated differently based on their chemical structures. All of these medications were FDA approved in the 1960s with the exception of the extended release version of diethylpropion which was approved in 2011. The side effect profiles are similar to phentermine and all can cause dry mouth, insomnia, heart palpitations, dizziness, and irritability.

Weight Loss Medication is Not a Magic Pill

Weight loss medications are tools for weight loss that serve several purposes. Weight loss medications help with appetite, cravings, energy, and fat loss but they are NOT magic pills! All FDA approved weight loss medications require proper monitoring with a licensed medical doctor and are used along with healthy nutrition and exercise.

Schedule an appointment to see if a weight loss medication is right for you.