The increasing popularity of weight loss drugs like Wegovy®, Ozempic®, Mounjaro™ and metformin may have you wondering how all these options stack up. Are there benefits to one over the other? How do side effects or drug interactions compare?
Both metformin and Ozempic can have positive impacts on weight management. We’ll cover everything you need to know about metformin vs Ozempic for weight loss, from side effects to cost and more.
Ozempic and metformin are both FDA-approved to treat type 2 diabetes mellitus, a common condition when the body doesn’t produce enough insulin. This hormone is made by your pancreas and helps your body use sugar for energy.
Having obesity or being overweight (defined as a body mass index or BMI of 27 kg/m or more) can raise your risk of type 2 diabetes, so losing weight may help prevent you from developing diabetes, according to the American Diabetes Association (ADA).
While both drugs are approved by the FDA for blood sugar control and prescribed off-label for weight loss, let’s start with the details on Ozempic.
If you’ve seen the news or read celebrity gossip lately, there’s a good chance you’ve heard of Ozempic. One of the brand names for the active ingredient semaglutide — others are Rybelsus and Wegovy — Ozempic is FDA-approved to help people with type 2 diabetes control their blood glucose levels (or their high blood sugar levels).
Ozempic is an injectable medication that may be used in combination with lifestyle changes like diet and exercise or with other diabetes medications like insulin or metformin.
Ozempic (and Wegovy) are supposed to be prescribed to people who have obesity or are overweight — in other words, those who have a body mass index (BMI) of 27 or higher. These drugs may also be used to prevent other health problems associated with excess weight such as high blood pressure or high cholesterol.
Curious about metformin, the other weight management drug? Here’s everything you need to know.
A biguanide medication used to control blood sugar levels, metformin is an oral medication that’s FDA-approved for people with type 2 diabetes. Off-label, metformin is also used to manage gestational diabetes (a type of diabetes that develops during pregnancy) and treat polycystic ovary syndrome (PCOS). It should not be used by people with type 1 diabetes.
But exactly how effective at weight loss are these two medications?
When metformin was tested on patients with diabetes in a large study in the ‘90s, researchers found that not only did the drug help prevent diabetes, but it also led to a significant decrease in weight and waist measurements for participants.
Specifically, metformin reduced participants’ diabetes by 31 percent over three years, and further studies found that those taking the drug for 29 weeks also lost 3.8 kg (or 8.4 pounds).
A more recent 2020 meta-analysis of 21 trials testing metformin found the drug had a clinically significant impact on lowering BMI, especially for those who were considered to have obesity.
Finally, a study of 154 people on metformin for weight loss found that participants lost an average of 5.6 to 7 kg (that’s roughly between 13 and 15 pounds).
Ozempic also has a notable effect on weight loss.
One study comparing a weekly semaglutide injection to a placebo in those without diabetes found a higher average weight loss in the semaglutide group — almost a 15 percent average decrease in weight, compared to a 2.4 percent average decrease in the placebo group.
But how does each of these diabetes medications actually work to help you lose weight?
Ozempic is in a class of drugs called glucagon-like peptide-1s (GLP-1s) receptor agonists. These drugs mimic GLP-1, a naturally occurring hormone, and target areas of the brain that regulate appetite.
Researchers aren’t entirely sure how metformin works, but the current top theory is that it causes your liver to make less glucose, which means less glucose is released into your bloodstream.
Said another way, metformin keeps your blood sugar in a healthy range by helping your body respond better to the insulin it makes. By regulating your blood sugar levels, metformin can also help reduce your risk of serious health issues like heart disease or loss of vision.
Metformin may also induce weight loss by working as an appetite suppressant. Like Ozempic, metformin increases the amount of GLP-1 hormone you make, which tells your brain that you're full and helps reduce the amount of calories you eat.
Metformin has also been shown to increase insulin sensitivity, meaning your body can use more of the insulin it produces and get more energy from your food intake.
Ozempic is a subcutaneous injection. This means the drug is injected into the tissue layer between the skin and muscle of the belly, upper arm or thigh.
Most people start with a weekly Ozempic dosage of 0.25mg, then increase the dose to 0.5 mg after four weeks.
Unlike Ozempic, metformin is an extended-release oral medication with a recommended starting (one month) dosage of 850mg once a day for diabetes. For weight loss, Hers offers access to a type of metformin called metformin XL at 500mg, which can be increased to 1000mg (and potentially more) over time.
It’s important to start at a lower dosage and increase it slowly, with the help of a healthcare provider, in order for your body to get acclimated to the medication. Your dosage will depend on your medical conditions, your weight and more. You should connect with a healthcare provider for medical advice on Ozempic vs metformin and what dosage is best for you.
Of course, both Ozempic and metformin come with a risk of side effects (really any medication does), but there are some distinct differences between them.
With Ozempic, the most common side effects include nausea, heartburn, constipation and diarrhea, which can be moderately severe in some people. In some cases, people using Ozempic can develop pancreatitis, a potentially serious condition.
There’s also an increasing amount of research and postmarketing reports of patients who started taking Ozempic suffering gastrointestonal ileus, or temporary stomach paralysis — enough that the FDA issued an update to Ozempic’s drug label.
Clinical trials have found that semaglutide has no negative drug interactions with common cholesterol or blood thinner medications.
Metformin, on the other hand, can cause side effects, including diarrhea, nausea, vomiting, abdominal pain or constipation.
Less common, but still usually minor, side effects of metformin include chest discomfort, headaches, sweating, hypoglycemia (low blood sugar) and weakness. A less frequent but severe side effect of metformin is lactic acidosis, where lactic acid builds up in the blood because the muscles can’t break down glucose.
It’s also worth noting that metformin is a much older medication than Ozempic — metformin was approved by the FDA in 1994 and Ozempic was approved in 2017 — which means there more research available about the safety and efficacy of metformin compared to Ozempic.
Cost is a big concern for any necessary medication, and the price of Ozempic vs metformin is especially important as they make headlines for their impact on weight loss. These medications usually aren’t covered by health insurance, making them quite costly.
Ozempic and Wegovy typically aren’t covered by insurance, which can make them quite costly. Without insurance, Ozempic can average around $900 per month and even approach $1000.
Metformin costs can vary, depending on your prescribed dosage and whether your insurance covers the medication. However, it’s going to be a fraction of the price of Ozempic as it’s a generic medication. Hers offers access to metformin as part of a comprehensive weight loss program, starting at $79 per month.
So, if cost is a consideration, metformin has the clear advantage..
Now you know all the facts on metformin and Ozempic for weight loss, so let’s compare these two medications and if one is better.
Both are FDA-approved diabetes drugs that lower blood sugar levels, though they work through different mechanisms. They may also both be prescribed off-label for weight management, as having obesity or being overweight can increase the risk of diabetes.
While Ozempic is a weekly injection that works to target your appetite, metformin is a daily oral medication that helps your body better respond to insulin and keep your blood sugar in a healthy range.
You may experience side effects like nausea and diarrhea from either medication.
As an older medication, metformin has a lot more research into its side effects and efficacy than Ozempic.
Ozempic is usually much more expensive than metformin, as there’s no generic version available and it’s usually not covered by health insurance.
Either of these prescription drugs may be recommended as a diabetes treatment or to reduce weight, which can help prevent diabetes or other health conditions caused by excess weight. Your healthcare provider can discuss more information about these and other weight loss medications with you.
Whatever treatment you choose, you should also plan to make lifestyle changes for weight loss, such as eating a healthy diet, getting regular exercise, aiming for seven to nine hours of sleep and more. There are also other weight loss treatments out there that don’t require the use of needles or injections.
Dr. Craig Primack MD, FACP, FAAP, FOMA is a physician specializing in obesity medicine.
He completed a combined residency in Internal Medicine and in Pediatrics at Banner University- Phoenix, and Phoenix Children's Hospital. He received post-residency training in Obesity Medicine and is one of about 7,000 physicians in the U.S. certified by the American Board of Obesity Medicine.
In 2006, Dr. Primack co-founded Scottdale Weight Loss Center in Scottsdale, Arizona, where he began practicing full-time obesity medicine. Scottsdale Weight Loss Center has grown since then to six obesity medicine clinicians in four locations around the greater Phoenix Metropolitan area.
From 2019–2021, he served as president of the Obesity Medicine Association (OMA), a society of over 5,000 clinicians dedicated to clinical obesity medicine. He has been on the OMA board since 2010, currently serving as ex-officio trustee.
Dr. Primack routinely does media interviews regarding weight loss and regularly speaks around the country educating medical professionals about weight loss and obesity care. He is co-author of the book, “Chasing Diets.”
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