How Does Wegovy (Semaglutide) Work?
Medically reviewed by Lindsay Cook, PharmD
Wegovy (semaglutide) is a prescription medication belonging to a group of drugs known as glucagon-like peptide-1 (GLP-1) receptor agonists. It comes as a liquid solution that you self-inject just below the skin once weekly.
The Food and Drug Administration (FDA) approved semaglutide as Ozempic for type 2 diabetes in 2017. Then, the drug was approved in 2021 under the brand Wegovy for weight loss, diet, and exercise.
Wegovy works by slowing the rate at which food moves through the stomach, known as gastric emptying.
This leads to changes in appetite, causing people to feel full more quickly and not feel hungry again after eating. Ultimately, this results in decreased calorie intake, promoting weight loss.
This article will explain how Wegovy works, its weight loss efficacy, potential side effects, safety and safety information, and other information regarding this drug's safe and effective use.
Understanding Obesity
About 42% of adults in the United States are obese, while another 30% are overweight. A body mass index (BMI) 30 kg/m2 or greater is considered obesity, while a BMI of 27 kg/m2 or greater is considered overweight.
Many factors can lead to weight gain and obesity. Diet and physical activity routines have a significant impact. Sleep habits, medications, and other medical conditions may also affect body weight.
In addition, genetics plays a role in determining why these factors can lead to more or less weight gain in some people than others.
Over the last 10 years, the percentage of Americans with obesity increased from 34% to 42%. This poses a severe public health crisis, as research shows obesity increases the risk of severe medical conditions, including diabetes, stroke, liver disease, and certain types of cancer.
Making diet changes and increasing your exercise routine is usually adequate for reducing body weight. However, lifestyle changes aren’t enough in some cases.
With new developments in anti-obesity medications and surgeries, more people are turning to their healthcare providers for weight loss when diet and exercise aren’t helping enough.
In certain situations, a healthcare provider may prescribe a medication to work alongside those lifestyle changes. It's important to know that GLP-1 drugs like Wegovy can help you lose weight, but they work best when you also stick to a healthy diet and exercise regularly.
Taking these steps together may give you better results than either option alone for weight management.
About BMI
BMI is a dated, biased measure that doesn’t account for several factors, such as body composition, ethnicity, race, gender, and age.
Despite being a flawed measure, BMI is widely used today in the medical community because it is an inexpensive and quick method for analyzing potential health status and outcomes
How Does Wegovy Work?
The FDA currently approves Wegovy, in conjunction with a reduced-calorie diet and increased exercise, for weight loss and weight management in:
Adults with an initial BMI of 30 kg/m2 (obesity)
Adults with an initial BMI of 27 kg/m2 (overweight) who have one or more weight-related health conditions, such as hypertension (high blood pressure), type 2 diabetes, or high cholesterol.
Children 12 and older with an initial BMI at the 95th percentile for their age and sex
Healthcare providers may prescribe Wegovy off-label for people who do not meet these criteria if they feel it is safe and beneficial for their patients.
Wegovy’s active ingredient is semaglutide, which belongs to the group of medications known as GLP-1 receptor agonists. Semaglutide is the active ingredient in two other brand-name drugs: Ozempic, a weekly injection, and Rybelsus, an oral tablet.
Unlike Wegovy, Ozempic and Rybelsus are specifically FDA-approved for controlling blood sugar levels in people with type 2 diabetes. Therefore, these medications do not promote weight loss in individuals without diabetes.
Wegovy works for weight loss by binding to the GLP-1 receptor, boosting the release of GLP-1 in the body. GLP-1 is a hormone that regulates appetite in the brain, providing the sensation of fullness that triggers our brain not to eat or stop eating.
By increasing the amount of GLP-1 released by the body, Wegovy increases the sensation of fullness. It also slows gastric emptying, thus slowing the food digestion process in the stomach.
Wegovy comes as a liquid solution in a prefilled injection pen. Each pen contains one dose. Wegovy is injected once per week as a subcutaneous injection, just under the skin of the abdomen, thigh, or back of the upper arm.
How Effective is Wegovy?
Most individuals using Wegovy with a reduced-calorie diet and increased physical activity exercise can expect to lose at least 5% of their initial body weight during the first three months of treatment.
For example, a person with an initial body weight of 200 pounds (lbs) can expect to lose 10 lbs during the first three months of Wegovy treatment.
In two clinical trials that led to Wegovy’s FDA approval, more than eight out of 10 people taking Wegovy achieved weight loss of 5% or more.
The results were significant compared to placebo-taking participants, demonstrating that Wegovy effectively enhances the impact of diet and exercise on weight loss.
More extensive weight loss is possible, especially if you continue taking Wegovy and closely adhere to long-term healthy lifestyle changes. In the clinical trials, about half of the participants took.
Wegovy achieved a 15% reduction in body weight after one year, while nearly 70% experienced a 10% reduction in weight loss.
On average, those receiving Wegovy in the clinical trials lost 15% of their body weight; the average trial participant weighing 231 lbs represents a 35 lb reduction in weight.
When you start taking Wegovy, you’ll start with a low dose and gradually increase it over time. Increasing the dosage too quickly could cause intolerable digestive side effects, such as nausea and vomiting.
Therefore, it’s important not to rush or speed up the dose increases to see results sooner. Instead, be patient and follow your provider's instructions.
Set realistic expectations that seeing the full benefits might take a few months. If you stop taking Wegovy, you might regain the weight.
When to Consider Wegovy
Intense diet and exercise changes alone have been shown to lead to significant weight loss (5-7% of body weight) but often reach a plateau and may lead to regained weight.
If you attempt lifestyle modifications before medications for weight loss and reach a point where you aren’t losing more weight, a medication like Wegovy may provide added benefit in conjunction with lifestyle changes.
You might consider Wegovy if you meet one of the following descriptions:
Age 18 or older with a BMI that is considered obese (BMI of 30 kg/m2 or above)
Age 18 or older with a BMI that is considered overweight (BMI of 27 kg/m2 or higher) and have one or more weight-related conditions (e.g., high blood pressure, high cholesterol, or type 2 diabetes)
Age 12 or older with a BMI at the 95th percentile, which means the child weighs more than 90% of other children of the same age and biological sex
BMI doesn’t consider your body composition, so it has downsides. However, BMI is still widely used in medical practice because it is a quick and easy way to assess a person’s body weight. If you’re unsure of your BMI, online BMI calculators and pediatric percentile resources are available.
Wegovy is not intended for any perceived aesthetic or cosmetic benefit to weight loss but rather for improved health and reducing your risk of cardiovascular problems associated with obesity.
Also, remember that Wegovy is expensive, upwards of $1,000 per month, and many health insurance plans do not cover weight-loss medications. This may change as we learn more about the potential for GLP-1 agonists to reduce the risk of heart problems.
Takeaway
In 2024, the FDA approved Wegovy to reduce the risk of serious heart problems in adults with obesity or who are overweight. Wegovy should be used in addition to a reduced-calorie diet and increased physical activity.
Who Should Avoid Wegovy?
Wegovy may not be safe for everyone. People with the following conditions or factors may have a higher risk of side effects if they use Wegovy:
People taking certain medications for diabetes
Healthcare providers may not prescribe Wegovy for you if you have or had:
An allergic reaction to Wegovy, semaglutide, or other GLP-1 medications
Personal or family history of certain thyroid cancers
Pancreatitis
Currently taking another GLP-1 medication
The FDA requires a boxed warning for Wegovy. A boxed warning is the most severe warning for a prescription drug. It informs patients and prescribers of potentially serious risks.
The boxed warning for Wegovy warns of the risk of certain thyroid cancers, which were found in animal studies of the GLP-1 medications. It isn’t known if Wegovy could cause thyroid cancer in humans.
As a precaution, people with a personal or family history of medullary thyroid cancer (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN2) should not take Wegovy, as it could further increase the risk of developing thyroid cancer.
Side Effects & Safety
Like all drugs, Wegovy carries the potential for adverse effects.
Therefore, if you or a loved one begins treatment with Wegovy, closely monitor for any emerging negative symptoms.
Common Side Effects
Common side effects of Wegovy may include:
Injection site reactions, such as skin itching or discomfort after you inject the medication
Nausea is the most common side effect of Wegovy. It most frequently occurs when you start the medication or after your dose increases. Nausea becomes less bothersome as your body adjusts to the medication or dose.
Talk to a healthcare professional if nausea or other common side effects persist. They may recommend changes to your diet, a temporary dose reduction, or possibly stopping Wegovy.
Severe Side Effects
Less commonly, Wegogy may cause serious side effects that require medical attention.
Potential side effects and their symptoms to watch for include:
Low blood sugar in people taking certain diabetes medications. Symptoms of low blood sugar to watch for are dizziness, sweating, or shakiness.
Severe stomach problems. Symptoms may include abdominal pain, vomiting, or diarrhea.
Gallbladder disease. Symptoms can include nausea, vomiting, abdominal pain, and itching.
Inflammation of the pancreas, which may cause nausea, vomiting, and abdominal pain.
Kidney damage. Symptoms may include fatigue, loss of appetite, or high blood pressure.
Increased heart rate, which may feel like your heart is racing or pounding.
Vision changes in people with type 2 diabetes.
Hypotension (low blood pressure), which may lead to dizziness or fainting.
Allergic reactions. Symptoms may include rash, nausea, or difficulty breathing.
Ileus. Symptoms include abdominal pain, vomiting, nausea, constipation, bad breath, and abdominal fullness.
The lists above do not include all possible side effects of Wegovy.
Dosage Guidelines
You can take Wegovy once weekly at any time, with or without food, on the same day each week.
The starting dosage for Wegovy is 0.25 milligrams (mg) injected once weekly for the first four weeks (Weeks 1–4), then your provider will escalate your dose every four weeks until you reach the maintenance dosage.
The table below summarizes Wegovy’s typical dosage:
Strengths available: | • 0.25 mg, 0.5 mg, 1 mg, 1.7 mg, and 2.4 mg |
How to administer: | • Inject subcutaneously (just under the skin) of the abdomen, thigh, or back of the upper arm |
Typical starting dosage and escalation schedule: | • Weeks 1–4: Inject 0.25 mg once weekly Weeks 5–8: Inject 0.5 mg once weekly |
Maintenance dosage schedule: | • 1.7 mg or 2.4 mg once weekly |
Maximum dosage: | • 2.4 mg once weekly |
Storage
Wegovy comes as a prefilled injector pen. Each pen contains a single dose. Until you’re ready to administer it, store Wegovy in the refrigerator.
Wegovy stays good at room temperature for up to 28 days as long as it’s unopened. If necessary for travel, you can store Wegovy pens out of the refrigerator for up to four weeks.
Wegovy Interactions
Certain medications interact with Wegovy. Interactions can lead to severe side effects or may cause medications to be less effective treatments than usual.
Before starting Wegovy, tell your provider about your current prescription, over-the-counter medications, and vitamins or supplements.
Wegovy may increase the risk of hypoglycemia If you also take certain diabetes medications to lower blood sugar, including:
Oral diabetes medications that enhance the release of insulin in the body, such as Glucotrol (glipizide) or Amaryl (glimepiride)
Insulin, such as Lantus (insulin glargine)
As a precaution, talk to a pharmacist or healthcare provider to check your medications and supplements to screen for potential interactions with Wegovy.
This is a partial list of medications that might interact with Wegovy.
Alternative Treatment Options
There isn’t a “natural” version of Wegovy or an herb that works similarly. There’s little evidence that any OTC dietary supplements are effective for weight loss.
The FDA warns that some herbs promoted for weight loss may be risky, especially for people treated for chronic conditions. Examples of supplements that pose potential health risks or drug interactions include glucomannan, hoodia, and Yohimbe.
Before trying a dietary or herbal supplement, consult a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider, to determine if it’s safe. Supplements are not intended to treat, cure, or prevent disease.
Summary
Obesity is linked to severe health problems. Wegovy has become a popular weight loss drug because it effectively reduces body weight with diet and exercise.
Clinical trial results also suggest the drug is associated with a decreased risk of obesity-related heart problems. Wegovy’s active ingredient, semaglutide, helps people lose weight by regulating appetite. When you feel fuller faster and for a more extended period, it’s often easier to stick with a healthy diet.
As with other medications, Wegovy poses potential risks and may cause side effects. As such, Wegovy is not FDA-approved for cosmetic weight loss in people who do not meet the overweight or obesity criteria defined in the drug’s labeling.
Consult a healthcare provider to determine if Wegovy may be an appropriate treatment option for you.
Frequently Asked Questions
What should I do if I miss a Wegovy dose?
Take Wegovy once each week at any time of day, with or without food, on the same day.
If you miss a dose and the next scheduled dose is more than 48 hours away, take the missed dose as soon as possible. If you miss a dose of Wegovy and the next scheduled dose is less than 48 hours away, skip the missed dose. Just take your next dose on your regularly scheduled day.
If you miss multiple doses of Wegovy in a row, consult a healthcare provider. To help minimize gastrointestinal (GI) side effects, they may have you restart the medication at a lower dosage and then follow the starting dosage escalation schedule.
Can I switch the day I use Wegovy?
Yes, you can change the day of the week you inject Wegovy. You may change the day of the week as long as your last dose was taken 48 hours ago or longer.
For example, if you regularly inject Wegovy on Mondays but want to change it to Tuesdays, you should wait until Tuesday to inject the next dose.
How can I dispose of my used Wegovy pens?
Since Wegovy pens contain a needle, they require particular disposal to protect others from coming in contact with the needle. After using the Wegovy pen, you can discard it in a sharps container.
You can get a sharps container from a pharmacy or use another container (such as an empty laundry detergent jug) if it is made of heavy-duty plastic that won’t leak and you label it “hazardous waste.”
Once your sharps container is about three-quarters full, follow local community guidelines to dispose of it safely.
Read the original article on Verywell Health.
