Questions and answers about the new anti-obesity medications

A blockbuster batch of anti-obesity drugs continues to grab headlines and dominate social media posts, and not just because the new year revs up our resolve to shed pounds. 

According to an article by Harvard Health, the medications — semaglutide (Wegovy), liraglutide (Saxenda), and tirzepatide (Zepbound) — are backed by science and stunning accounts of people losing as much as 20% of their body weight.

While that's remarkable, it's not the whole story. Many questions about the drugs remain, and some answers are complicated.

What are they?

The newly FDA-approved medications for treating obesity fall within the category of GLP-1 receptor agonists (GLP-1s). These drugs replicate the actions of a hormone called glucagon-like peptide 1 (GLP-1), which aids in slowing stomach emptying, regulating blood sugar levels, and suppressing appetite—a combination that results in weight loss. 

Among these medications, Zepbound not only mimics GLP-1 but also emulates the effects of another hormone known as glucose-dependent insulinotropic polypeptide (GIP), thought to enhance the impact of GLP-1.

"Many people say these anti-obesity medications have changed their lives," says Dr. Caroline Apovian, an obesity medicine specialist and co-director of the Center for Weight Management and Wellness at Harvard-affiliated Brigham and Women's Hospital.

"The medications may even affect the reward center in the brain, the part that enables you to eat chocolate cake even though you're full. These drugs seem to dampen the reward response, which also may reduce addictive behaviors like cravings for alcohol, sugar, and nicotine," Dr. Apovian says.

Wait — aren't they diabetes drugs?

All three of the anti-obesity medications were initially granted FDA approval for diabetes treatment, marketed under the brand names Ozempic, Victoza, and Mounjaro.

However, individuals taking these drugs observed significant weight loss, a phenomenon later substantiated by studies. Consequently, the FDA subsequently granted approval for these medications to be used specifically for weight loss, introducing new brand names: Wegovy, Saxenda, and Zepbound. When prescribed for overweight or obesity, the drugs are typically administered in higher doses compared to their diabetes counterparts.

While there are older GLP-1s like dulaglutide (Trulicity) approved for diabetes, their impact on weight is generally less pronounced.

How do you take the medications?

Most of these new drugs come in the form of injections that you give yourself daily or weekly. They are loaded in an injector pen (like an EpiPen for an allergic reaction) that you press against your abdomen or thigh.

A pill form of semaglutide (Rybelsus) is also available. It's FDA-approved to treat diabetes, but not yet approved for weight loss. Several other pill formulations are being tested.

What are the side effects?

Both the anti-obesity and diabetes formulations have potential side effects. Common ones include fatigue, nausea, vomiting, or constipation. Dr. Apovian says those tend to go away after a few weeks.

In rare cases, the drugs might cause an obstruction in the small bowel, gastroparesis (stomach paralysis), or inflammation of the pancreas (pancreatitis).

"As far as I know, side effects are not permanent. They go away if you stop taking the medications," Dr. Apovian says. But the very long-term effects of taking the newer medications are not yet known."

Who's a candidate for the drugs?

The drugs are approved for weight loss only in people diagnosed with obesity (a BMI of 30 or greater) or a higher range of overweight (a BMI of 27 to 29.9), as well as a medical problem related to excess weight, such as high blood pressure or high cholesterol. Of course, that hasn't stopped some people who don't meet these criteria from using them.

Because these drugs are new and powerful, and are the subject of intense study, it is expected that recommendations as to who should use them will change in the coming years. Researchers are likely to identify new groups of people who might benefit — or, conversely, people who may be at extra risk from drug side effects.

How long do you take the drugs?

Taking one of the new GLP-1s is not a short-term solution. Once you go on the drug, you must stay on it indefinitely to keep getting the benefits. You regain the weight if you stop taking the medications.

"Overweight and obesity, like diabetes and hypertension, are serious conditions that often require ongoing, even lifelong treatment. There are no 'one-and-done' treatments," Dr. Apovian says.

Costs and coverage

Spectacular results don't come cheaply, and the new drugs range from about $900 to $1,600 per month. Don't expect your insurance to pay for them. Medicare does not cover the anti-obesity medications, and Medicare coverage for the new diabetes drugs is iffy and partial at best, depending on your plan. Private insurance often will pay for the drugs to treat diabetes, as long as you've tried other diabetes treatments without success. But Dr. Apovian says only about 20% to 30% of private insurers currently are covering the anti-obesity formulations.

Some manufacturers of GLP-1s offer coupons with steep discounts, but many pharmacies don't accept them. And beware of budget-friendly versions touted in online ads or offered by "med-spas." Dr. Apovian says these are compounded (custom-mixed) drugs brought in from other countries, with no oversight by the FDA, and no guarantee of what they contain.

Are they even available?

To make matters worse, the drugs' frenzied rise in popularity has now caused shortages, making them hard to find. "The shortage has to do with the manufacturers not anticipating this kind of demand," Dr. Apovian says. "Over 40% of Americans have obesity. The drug companies didn't anticipate how many of them would want to use the medications. The companies are trying desperately to make enough supplies as we speak."

Until they do, and until more insurance companies cover the medications or manufacturers are forced to lower prices (both of which are being debated in Congress), many people with serious medical conditions are finding that they must forgo the most effective anti-obesity drugs we've ever seen.