What you need to know about the latest weight-loss drugs

by Kaiser Permanente |
Two friends smiling and walking up stairs while holding weights

Between work, errands, and family responsibilities, finding time for yourself is hard enough. Add in stress or limited access to nutritious food, and making time to maintain a healthy weight can feel nearly impossible. So it’s easy to see the appeal of weight-loss drugs. Instead of exercising or cooking healthy meals, you just take a pill. But is it really that simple? Do those medications even work? And how do they affect your health?

Lately, GLP-1 drugs are filling headlines for one reason: weight loss. But these drugs also have other, more harmful side effects. To help you learn more about prescription drugs for weight loss, we spoke with Regina Ragasa, DO, the Southern California regional co-chair of lifestyle medicine at Kaiser Permanente.

What are GLP-1 drugs?

Glucagon-like peptide 1 (GLP-1) agonists — including brand names like Ozempic and Wegovy — were created to help people with type 2 diabetes make more insulin and lower their blood sugar.1 But they’re often not the first line of defense.

“GLP-1s are relatively new drugs, and there are a lot of unknowns about side effects,” says Dr. Ragasa. “Usually, patients living with diabetes will have to try multiple drugs before we resort to giving them a GLP-1 medication.”

Do GLP-1s really help you lose weight?

On average, people lose 15% of their body weight on GLP-1s.2 But the medication doesn’t magically melt fat.

GLP-1s slow down your digestion and make you feel fuller longer, explains Dr. Ragasa. Some people who take them also have fewer cravings for processed foods. In other words, people often lose weight on GLP-1s because they’re eating less — and these appetite changes don’t last after they stop taking the medication.

People usually stop taking GLP-1s for weight loss after 1 to 2 years, says Dr. Ragasa. After that, studies show they regain most of the weight within the next year.3

“Without lifestyle changes, the weight loss people see while taking GLP-1s usually doesn’t last,” she explains. “Studies have shown that patients end up gaining about 60% to 70% of their weight again after coming off the medication. This can be frustrating because they’ve worked so hard to keep that off.”

What are the other side effects of GLP-1s?

While weight loss might make people seek out GLP-1s, the drugs are still new — and recent studies show that they can have negative side effects:

  • 4 in 5 people feel mild to moderate stomach side effects like nausea, vomiting, and diarrhea.4
  • Users have 4 times greater risk for stomach paralysis and bowel obstructions and 9 times greater risk for pancreatitis.5
  • Up to 40% of the weight people lose on GLP-1s is lean muscle mass, not fat.6
  • GLP-1s may increase depression and risk for suicide in some patients.7

For many of these reasons, Dr. Ragasa may not turn to GLP-1s for her patients who want to lose weight. If lifestyle changes like diet and exercise aren’t enough, she’ll discuss medications with a longer history of success.

“We have decades of experience with phentermine and use it very successfully in weight loss,” Dr. Ragasa says. “Because of the nature of phentermine, we can find an effective dosage much more quickly.” But she emphasizes that drugs are just one option for weight loss, and they can’t keep you healthy on their own.

What’s the best way to lose weight?

Getting fit is about more than just losing pounds. It’s about forming healthy, long-term habits. Eating healthy, being active, and managing stress are all part of improving your health and losing weight. So it’s important to work with your doctor to find a routine that makes you feel good in mind, body, and spirit.

When Dr. Ragasa prescribes weight-loss medication, she also recommends patients take up strength training and change their diet. In fact, she spends most of her time with patients discussing how to eat differently and providing them with healthy recipes.

“I tell my patients to choose high-quality proteins like beans and lentils. Any plant proteins naturally have vitamins, antioxidants, fiber, and all these nutrients that nourish the body,” she says. “When my patients stick to a more plant-based diet, they end up losing a significant amount of weight. And they’re able to keep it off.”

Create your healthy lifestyle toolkit

Being mindful about nutrition and exercise isn’t always easy. Creating a healthy lifestyle toolkit can help you when you aren’t sure what to eat or aren’t feeling motivated to exercise. Try adding a few activities, or “tools,” like these to your routine to make it fun and easy to stay healthy:

  • Make a list of easy healthy recipes — Keep the list handy so you can reference it at the grocery store. That way you’ll have the ingredients you need to make a quick, delicious, and healthy meal when you’re tired or short on time.
  • Schedule a walk with a friend — Exercise doesn’t have to be a chore. When you walk with a friend, you get to enjoy one another’s company and feel supported as you improve your health.
  • Plan a healthy picnic — Getting outside for some fresh air and spending time with loved ones are both great for your health. Plan a picnic where everyone brings something healthy to get the most out of the experience.

While GLP-1s are popular right now and have helped many people lose weight, the side effects are still being studied. Keep in mind that no weight-loss drug is a substitute for a healthy lifestyle, and everyone’s needs are different. If you’re thinking about losing weight, talk to your doctor about what options are right for you and your health.

1Kaiser Permanente does not endorse the medications or products mentioned. Any trade names listed are for easy identification only.

2Shohinee Sarma et al., “Weight Loss Between Glucagon-Like Peptide-1 Receptor Agonists and Bariatric Surgery in Adults with Obesity: A Systematic Review and Meta-Analysis,” Obesity, November 30, 2022.

3John Wilding et al., “Weight Regain and Cardiometabolic Effects After Withdrawal of Semaglutide: The STEP 1 Trial Extension,” Diabetes, Obesity, and Metabolism, May 19, 2022.

4Allison Nguyen, “What We Know About Semaglutide Adverse Events and Gastroparesis: Part 1,” Gastroenterology Advisor, September 1, 2023.

5Peter Lin, “Risk of Gastrointestinal Adverse Events Associated With Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss,” Journal of the American Medical Association, October 19, 2023.

6Noah Tong, “Omada GLP-1 Program to Prioritize Muscle Mass Restoration Through Expanded Care Track,” Fierce Healthcare, February 13, 2024.

7Pandora Dewan, “Ozempic ‘Fatal Outcomes’ Study Raises Serious Concern,” Newsweek, February 16, 2024.