What Are Anti-Obesity Medications and How Do They Work?


Dr. Scott Isaacs

The magic pill has been the Holy Grail since oral medications were first invented. Imagine taking one pill and waking up the next day completely cured of whatever ails you. While many pills do, in fact, perform small feats of magic in helping us manage medical issues, the overnight sensation of a magic pill is still not here. And this is especially true when it comes to managing weight issues. At Atlanta Endocrine Associates, Dr. Scott Isaacs offers accurate diagnosis and state-of-the-art weight management. To learn more, contact the office in Atlanta, Georgia or request an appointment online. But that isn’t to say that medications can’t help in the battle against obesity. Here at Atlanta Endocrine Associates, we’ve successfully helped many of our patients in Atlanta, Georgia, lose weight and keep it off with the help of anti-obesity medications. Here’s a look at these anti-obesity medications and how they work.

The problem

Obesity, or adiposity, affects an incredible 650-700 million people worldwide, including 93 million in the United States, and those numbers continue to increase each year. To say that obesity is an epidemic would not be overstating matters. Unfortunately, it’s an epidemic that has life-or-death consequences, thanks to the health complications that are brought on by obesity, which is why the medical world has been scrambling for years to produce a solution. The biggest problem lies in the fact that long-term weight loss is extremely difficult, even with the proper diet and exercise. While you may benefit from a short-term loss in weight, your hormones often end up working against you, increasing your appetite, and lowering your metabolism. And willpower alone isn’t usually strong enough to face off against these biological impulses to eat more.

The solution

Since your hormones control your appetite and your metabolism, many researchers have focused on ways to override your hormones, as well as change the way your body processes fat. The resulting medications aren’t magic, so far, but they’ve helped many people take the weight off when nothing else worked. Medications that have been approved by the FDA, include:

Phentermine (Adipex-P®, Lomaira®)

Phendimetrazine (Bontril®)

Benzphetamine (Regimex®, Didrex®)

Orlistat (Xenical®, alli®)

Phentermine and Topiramate ER (Qsymia®)

Naltrexone HCl and Bupropion HCl (CONTRAVE®)

Liraglutide injection (Saxenda®)

Semaglutide injection (wegovy®)


A new medication, tirzepatide (Mounjaro) acts on two different receptors for hunger hormones GIP and GLP-1 and is known as a "twincreatin" because of this dual effect. Reported average weight loss is an amazing 22.5%, more than any medication for weight loss, approaching numbers seen with bariatric surgery.

The short view

For short-term weight loss, either to kick you off on a broader weight loss plan or because you need to lose weight quickly for a looming medical issue, phentermine, phendimetrazine, and benzphetamine are the most effective. These medications contain mild stimulants that decrease your appetite. We don’t recommend these types of appetite suppressants for long-term use, since your body builds up a tolerance toward them after a few months. You also shouldn’t use these medications if you have heart or other medical issues that won’t tolerate the stimulants well. For most patients, we prescribe these medications for periods of up to 12 weeks, or 24 weeks if you’re taking the pills every other day.

The long view

For patients who want a long, controlled approach to weight loss, the other drugs on the list above have helped patients lose an average of 5-15% of their body fat in 6-12 months. And here’s, briefly, how each works:

Orlistat: Blocks the absorption of up to one-third of the fat in each meal

Phentermine and topiramate ER: A combination approach that suppresses appetite

Naltrexone HCI and bupropion: Two medications that work together to reduce appetite and cravings

Semaglutide or Liraglutide: A synthetic hormone injection that reduces appetite and makes you feel full.

Plenity: A capsule taken with water before meals that swells and fills the stomach. Each of these medication protocols are designed and tested for long-term use.

Not for everyone

While we saved this point for last, it’s the most important one. Anti-obesity medications are only available to those who are classified as obese with a body mass index (BMI) of 30 or higher or people with a BMI above 27 and at least one serious health complication because of their weight. In addition to these restrictions, we don’t just hand you a prescription and stop for the day. We still have a lot of work to do in changing your nutrition and exercise habits, and you need to keep your caloric intake to under 1,200-1,400 every day. Rest assured, we’re here to help and provide you with the tools necessary for appreciable and healthy weight loss. If you’d like to learn more about anti-obesity medications, please feel free to call us.