How does Ozempic work?

Even with exercise and diet, it can be challenging to lose weight and sustain that weight loss long-term. Thankfully, some medications can help. Ozempic, a diabetes medication, is one medication that can be prescribed off-label for weight loss. Let’s break down how the weekly diabetes injection works and how it can lead to weight loss.

Ozempic (semaglutide; see Important Safety Information) is a diabetes medication manufactured by Novo Nordisk. Ozempic is prescribed to treat type 2 diabetes when dietary changes and exercise do not adequately lower blood sugar levels. Adding Ozempic to a treatment plan that includes lifestyle changes like diet and exercise, or other diabetes medications such as metformin or insulin, can significantly improve glycemic control in people with type 2 diabetes (Chamberlin, 2019). For people with type 2 diabetes and heart disease, using Ozempic also reduces their risk of stroke, heart attack, or death from a cardiovascular event (FDA, 2020).

Ozempic is a prefilled prescription pen that you inject subcutaneously (under the skin) into your abdomen, thigh, or upper arm weekly. You can take Ozempic with or without meals (FDA, 2020). 

Common Ozempic side effects include nausea, vomiting, diarrhea, abdominal pain, and constipation. Serious side effects may include pancreatitis, diabetic retinopathy (vision loss caused by diabetes), hypoglycemia (low blood sugar), kidney failure, or an allergic reaction to the ingredients in Ozempic (FDA, 2020). 

Ozempic should not be used by children, people who are pregnant or breastfeeding, or anyone with (Chamberlain, 2019; FDA, 2020):

• Pancreatitis

• A personal or family history of thyroid cancer

• Multiple endocrine neoplasia syndrome type 2

The US Food and Drug Administration (FDA) has issued a “black box” warning for Ozempic, the most severe advisory they give for a medication. Animal studies have found that Ozempic increases the risk of thyroid tumors in mice and rats. While it is not known if Ozempic has the same effect in humans, people with a personal or family history of thyroid cancer or who have multiple endocrine neoplasia syndrome type 2 should not use Ozempic (FDA, 2020).

Ozempic is a glucagon-like peptide-1 (GLP-1) receptor agonist, which means it mimics the GLP-1 hormone produced in your gut. When GLP-1 binds to GLP-1 receptors, it tells your pancreas to release insulin whenever your blood sugar levels get too high, which brings your blood sugar back down (Shah, 2014; Phillips, 2022). In type 2 diabetes, your body develops insulin resistance, which allows sugar to build up in the blood. Antidiabetes medications like Ozempic encourage the release of more insulin to keep blood glucose levels in check (Thota, 2022; Phillips, 2022).

In addition to stimulating insulin release, Ozempic reduces the amount of sugar released from your liver. Ozempic also slows down the digestion process, so it takes longer for your stomach to empty fully, a process known as gastric emptying. This helps prevent your blood sugar from spiking. At the same time, it keeps you feeling full for longer, which can lead you to eat less and lose weight (Shah, 2014; Phillips, 2022).

Because GLP-1 receptor agonists like Ozempic have led to weight loss in people with type 2 diabetes, researchers have looked into whether they can help treat obesity and lower some of the cardiovascular risks associated with obesity. Indeed, long-term GLP-1 medication usage seems to lower blood pressure and cholesterol (Phillips, 2022). Some adults with obesity may be prescribed Ozempic off-label for weight management. Combined with diet and exercise, Ozempic can help people with obesity lose weight faster (O’Neil, 2018; Wilding, 2021).

Ozempic is a long-acting medication, and it may take up to eight weeks for you to fully feel its effects. Health providers prescribe Ozempic at a lower starting dose, such as 0.25 mg. The lower starting dose may make it easier for your body to adjust to using Ozempic, which can help reduce side effects. After four weeks of using Ozempic, your dose may increase to 0.5 mg. After another four weeks, they may increase to your final dose if additional glycemic control is needed (FDA, 2020).

When it comes to weight loss, it’s more of a gradual process that depends on your current body weight and health conditions (Phillips, 2022). Clinical trials looking at the effects of Ozempic for more than a year often found that people with type 2 diabetes and a body mass index (BMI) of 27 or higher lost nearly 10% of their body weight when taking semaglutide (the active ingredient in Ozempic). Those taking a placebo lost less than 4% (Davies, 2021).

In another study, people who had obesity but not diabetes lost between 6% to 13.8% of their body weight by the end of one year, with those who took a higher dose of semaglutide losing more weight. Up to 65% of those taking semaglutide lost at least 10% of their body weight within the trial period (O’Neil, 2018).

In a clinical trial of people taking Ozempic for type 2 diabetes, participants lost around eight to 10 pounds by week 30. Similar to the other study, participants who took a higher dose of Ozempic lost more weight than those taking a lower dose (DailyMed, 2022). 

Research shows that people with type 2 diabetes experience more weight loss when they take Ozempic in addition to metformin or insulin (Chamberlin, 2019). For example, individuals with type 2 diabetes taking both Ozempic and metformin lost around 12 to 14 pounds by week 40 (DailyMed, 2022). 

Semaglutide, the active ingredient in Ozempic, is available in other diabetes and weight loss drugs (FDA, 2021). Some of these drugs, like Wegovy (see Important Safety Information), are approved for chronic weight management, while others, like Ozempic, are approved to treat type 2 diabetes but may be prescribed off-label in adults for weight loss. Health care professionals usually recommend starting with increased exercise and a lower-calorie diet, but if sufficient weight loss is not achieved within six months, they may recommend prescription medications (Phillips, 2022).

Talk to your healthcare provider about using a drug like Ozempic for weight loss. 

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Current version

August 16, 2022

Written by

Amelia Willson

Fact checked by

Chimene Richa, MD

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About the medical reviewer

Chimene Richa, MD

Dr. Richa is a board-certified Ophthalmologist and medical writer for Ro.