GLP-1 Medications: What Ozempic and Similar Weight-Loss Drugs Actually Do

Endocrinologists Dr. Sheree Bondoc and Dr. Sue Lim explain how they work, who may benefit, and what to know about side effects, risks, and proper use.

Over the past few years, Ozempic has become a hot topic in several health-related discussions. Between 2021 and 2023, the drug gained attention as media coverage, celebrity rumors, and off-label prescriptions for weight loss surged, leading to widespread global demand and periodic shortages. But what is Ozempic, and what is it used for?

For starters, Ozempic belongs to a class of drugs called GLP-1 receptor agonists. GLP-1 stands for Glucagon-like Peptide-1, which is a hormone that our intestines naturally release after eating and that regulates blood sugar, appetite, and digestion. GLP-1 medications are designed to mimic or enhance this function, helping the pancreas release insulin when blood sugar rises, influence appetite centers in the brain, and slow the movement of food through the stomach. By taking GLP-1 medication, you could get better blood sugar regulation, less hunger, earlier satiety, a reduction in “food noise” (the constant thought of what to eat next), and weight loss.

The latter effect may catch people’s attention, as many live with metabolic and hormone-related conditions that can cause weight gain, such as obesity. However, the conversation is a little bit more nuanced than that.

According to Core Clinic co-founder Dr. Sheree Bondoc, GLP-1 medications were originally developed to treat type 2 diabetes. As patients had improvements in blood pressure, cholesterol, and other metabolic markers, weight loss was a significant effect that led to obesity trials. After years of research, we now know that GLP-1 therapies can improve several markers of cardiometabolic health and reduce cardiovascular events.

“For many years, obesity was treated mainly with advice to ‘eat less and move more,’ which oversimplifies a complex medical condition,” she says. “GLP-1s have shifted the conversation by showing that biology, hunger hormones, brain signaling, insulin resistance, and genetics play a major role in body weight.”

“Some individuals use it for many reasons, and we really hope that they’re using it for the reasons and are guided, because there’s no quick-fix solution,” says Dr. Sue Lim, head of the Obesity, Lipid, and Nutrition Advocacy Council of the Philippine Society of Endocrinology, Diabetes, and Metabolism.

Below, Dr. Bondoc and Dr. Lim share key information to consider when considering taking the medication.

GLP-1 medications can affect your appetite, hunger, and feelings of fullness

Physiologically, the feeling of being less preoccupied with food is because GLP-1 medications slow down gastric emptying and act on appetite centers in the brain. But the medication is not meant to remove appetite completely, but to make it more manageable and support healthier intake.

“I always tell patients: ‘Hunger is still an important biological signal,’” Dr. Bondoc says. “If someone is barely eating because the medication has suppressed their appetite so aggressively, I don’t necessarily consider that successful treatment.”

You cannot take GLP-1 medications for cosmetic weight loss

“Wanting to be thinner is not, by itself, a medical indication for using it,” she says. When consulting for GLP-1 medication, Dr. Bondoc shares that they take a look at the patient’s BMI and waist circumference, body composition, visceral fat, insulin resistance, fatty liver, blood pressure, cholesterol, sleep apnea, cardiovascular risk, previous attempts at weight management, and other health conditions.

“Medical management is aimed at improving something meaningful: visceral fat, insulin resistance, fatty liver, cardiovascular risk, mobility, fertility, sleep apnea, inflammatory burden, or another obesity-related complication,” she says. For women, she says, being excessively lean while sacrificing muscle, bone density, adequate nutrition, menstrual health, or hormonal health is not a longevity strategy.

You can regain weight after pausing the medication

According to Dr. Lim, you can regain two-thirds of the weight you lost when you pause taking the medication. While some patients might use the medication to lose weight short-term, pause, and retake it again, she also cautions against doing so, as weight fluctuations can also be harmful to the body. The goal, she says, is to build a lifestyle that can be sustained long-term.

GLP-1 medications can have various side effects

When you begin taking GLP-1, you may experience common side effects such as nausea, constipation, diarrhea, bloating, reflux, and sometimes vomiting. However, if you begin to experience persistent vomiting, inability to keep fluids down, severe or persistent abdominal pain, significant dehydration, or symptoms suggesting gallbladder disease or pancreatitis, Dr. Bondoc urges that you have a medical assessment.

According to her, the more common side effects are dose-related and may improve as the body adjusts. “This is one reason I don’t believe in rushing patients to the highest dose. The best dose is not necessarily the highest dose. It is the lowest effective dose that produces the desired metabolic response while allowing the patient to eat, function, and feel well,” she says.

It can make you lose muscle mass

If the medication is not supported by necessary lifestyle changes, it can make the body lose a lot of muscle. “Although the percentage of the loss is greater for fat than muscle, you still lose muscle, and we need muscle because it is healthy for insulin sensitivity, and it also impacts metabolic health,” Dr. Bondoc says.

Do not take GLP-1 without medical supervision

While its benefits might tempt you, Dr. Bondoc warns against seeking the medication without a consultation. Doing so can lead to dehydration, undernourishment, constipation, nausea, muscle loss, gallbladder issues, rapid weight loss, and other medical complications. “A GLP-1 medication is not a beauty supplement. It is a powerful prescription therapy,” Dr. Bondoc says.

If you are pregnant, dealing with gastrointestinal motility problems, have previous pancreatitis or gallbladder disease, certain eating disorders, and other medical issues, you may not qualify for GLP-1 medication.

GLP-1 must be supported with sleep, diet, and exercise

According to Dr. Bondoc, there is no special “GLP-1 diet,” but rather that when you’re on the medication and have less appetite, nutritional priorities change. On top of the nutrient list is protein, to prevent excessive muscle loss. She also highly recommends fiber, fluids, and electrolytes, especially for those who are experiencing constipation or eating little. Lastly, depending on the patient’s clinical situation, iron, vitamin B12, folate, calcium, vitamin D, and other micronutrients may need attention as well.

For Dr. Lim, one of the simplest but highly impactful nutritional changes is to remove processed foods and sweetened beverages and focus on whole foods.

In addition to a more nutritious diet, she strongly suggests resistance training, which can help preserve muscle, support metabolism, improve insulin sensitivity, and protect bone health. “It’s better to lose weight a little more slowly while becoming stronger than become rapidly smaller but metabolically weaker,” she says. But Dr. Lim notes that any movement is encouraged, even with just the simple goal of hitting 8,000 steps a day, stretching, or doing home exercises.

She also adds that sleep is nonnegotiable. “If you don’t have enough sleep, not only are your hormones going to be out of whack, it will also not be supportive of being active,” she explains. “Even if you eat healthy, you sleep, and move a lot, if you don’t have enough sleep, you don’t recover, you don’t regenerate, you don’t heal.”

The duration of GLP-1 usage depends on the patient’s condition

For those who are dealing with obesity as a chronic disease, long-term therapy may be more appropriate, coupled with long-term medication for hypertension or cholesterol. “But that does not mean every person who starts GLP-1 must automatically remain on the same dose forever,” Dr. Lim clarifies. Other patients, she says, may transition to a lower maintenance dose. Some may discontinue treatment after reaching metabolic goals and establishing lifestyle changes. “There is interindividual variability. Some respond, and some don’t; some have side effects,” she adds.

From an endocrinologist’s perspective, patients with success with GLP-1 have improved waist circumference and visceral fat that are improved, healthier glucose regulation, a fatty liver that is improving, better blood pressure and lipids, decreased inflammation, and improved sleep and energy. “The goal is metabolic independence: giving the patient as many tools as possible to maintain health over the long term,” she says.

GLP-1 does not permanently “reset” your metabolism

While GLP-1 medications can improve metabolic function, there is no evidence that a course of GLP-1 medication rewires the body so that the weight can never return. “What can change long-term are things that the patient builds during the treatment: more muscle, better food habits, improved fitness, better sleep, reduced visceral fat, and a completely different understanding of how their body responds to food and activity,” Dr. Bondoc says.