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Blog - The science behind Semaglutide

The Science Behind Semaglutide

It’s hard to avoid ads for Ozempic (semaglutide) these days. Everywhere you look, people seem to be shedding unwanted pounds thanks to semaglutide injections. You probably know people who have stopped overeating and are going down in clothing sizes month by month.

But does semaglutide really work? Is the magic bullet it seems to be? How does it work in the first place? Let’s dig into the science behind semaglutide (the generic name for the medication also sold as Ozempic and Wegovy) to understand what a game-changer it actually is for weight loss.

What Is Semaglutide?

Semaglutide is a GLP-1 agonist. That means it mimics the actions of GLP-1, which is short for glucagon-like peptide-1. GLP-1 is a hormone that your body produces naturally after you eat. It stimulates the release of insulin in response to food intake, which in turn helps regulate your blood sugar.

With these functions, it’s no surprise that semaglutide has been used as a treatment for type 2 diabetes for many years. But GLP-1 does far more than just regulate blood sugar. This hormone also helps you feel full when you eat. It slows down the rate at which your stomach empties, and it helps keep your appetite under control. That makes it also highly useful for those hoping to lose weight, whether they have type 2 diabetes or not.

How Does Semaglutide Work?

When you eat, the hormone GLP-1 gets to work in your gut to rev up insulin production in response to the glucose released from the food you just ate. It also tells your hypothalamus when it’s time to stop eating. As a GLP-1 receptor agonist, semaglutide does the same thing. It replicates natural GLP-1 in the gut, travels through the bloodstream, and binds to GLP-1 receptors in the hypothalamus.

Once it reaches the hypothalamus, semaglutide gets to work. Receptors for GLP-1 are located in the area that controls eating and appetite, heart rate, blood pressure, hydration, and excretion of sodium. When it binds to the receptors, semaglutide triggers the release of insulin, helping keep blood sugar in control. And, as a bonus, semaglutide performs this function for a longer period of time than the naturally produced hormone.

Semaglutide is delivered via a weekly injection. While a version of semaglutide is available in pill form (sold under the brand name Rybelsus), it’s not quite as effective and must be taken daily.


When taken regularly, semaglutide has a marked effect on the body’s weight management. This effect shows up in several different ways.

Decreased Hunger and Appetite

When semaglutide binds to those GLP-1 receptors in the hypothalamus, it sends your body a signal that you’re full and don’t want to eat more food. Because you’re not hungry, you eat less — and you do so because you don’t want to eat, not because you’re straining your willpower to the limit. This makes it easier to make healthier, more mindful food choices, since you’re no longer driven by food cravings and you no longer feel deprived. You’re simply not motivated to eat, so you consume few calories naturally.

Slowed Emptying of the Stomach

Semaglutide also slows down the rate at which your stomach empties. That means you feel full earlier during a meal, and you keep feeling full longer. As a result, you’re far less likely to overeat or to snack between meals. You’re less likely to indulge in cravings because you’re already full.

Reduction of Visceral Fat

Semaglutide triggers the breakdown of fat, encouraging lipolysis, or the release of fat from fat cells. Its effect is particularly strong around visceral fat, which is the fat surrounding your internal organs (including belly fat). Instead of clinging dormant to your body, this fat is released to be burned as energy. As a result, you lose weight and develop a leaner body.

Greater Metabolic Burn

Research shows that semaglutide boosts your basal metabolic rate, or BMR. That’s the number of calories your body burns when resting. Because your BMR is enhanced, you end up burning calories more efficiently, so that you’re losing (small amounts of) weight even when you’re not physically active.

Targeting of Neurological Rewards

Semaglutide also has an effect on the reward sensations of your brain. Those reward centers are what trigger cravings for rich, caloric foods, making it hard to stay on a diet or exercise willpower. Semaglutide dampens down those neural pathways so you simply aren’t so attracted to indulgent foods. As a result, what used to require enormous willpower now seems natural, and you can avoid cravings easily.

The Health and Weight Loss Benefits of Semaglutide

Semaglutide helps people deal with negative eating behavior in a healthy way. Because you have less desire to eat, you’re less likely to binge eat or to turn to food for comfort. Eating less naturally results in weight loss.


And the weight losses that come with taking semaglutide result in expanded health benefits. You can expect to see your cholesterol and triglyceride numbers drop, along with your A1C and blood pressure levels. Waist circumference, which is an indicator of cardiovascular risk, will also decrease.


In addition, many people on semaglutide report that their cravings for tobacco and/or alcohol also diminish while on the medication. More study is needed to determine the link here.

How Effective is Semaglutide?

Long-term data on semaglutide won’t be available for a while, since the medication has only been on the market since 2017. Early studies, however, are remarkably encouraging.


A 2021 study following 2,000 participants who had been diagnosed with obesity but not with type 2 diabetes showed that half those in the study lost 15% of their total body weight after 68 weights. Almost a third of the participants did even better, losing 20% or more of their body weight. Participants who followed a diet and exercise program but didn’t take semaglutide only lost 2.4% of their total body weight.

Similar studies report weight loss of about 15% of body weight after 2 years on semaglutide, with those taking a placebo only losing about 2% of their body weight. More recent studies continue to show similar results. One caveat, though: once participants stop taking semaglutide, they are likely to regain the weight they’ve lost.

Who Can Take Semaglutide? (And Who Shouldn’t?)

Eligibility for semaglutide for weight loss is determined based on FDA regulations and stringent safety measures. Individuals who are considered suitable candidates typically include those with a body mass index (BMI) of 30 or higher. Alternatively, individuals with a BMI of 27 or higher, coupled with existing cardiovascular conditions such as heart disease, high blood pressure, high cholesterol, or other related conditions, may also qualify.

However, it’s crucial to assess medical history thoroughly. Semaglutide may not be appropriate for individuals with a personal or family history of specific conditions, including medullary thyroid cancer, gallbladder disease, multiple endocrine neoplasia syndrome type 2 (MEN-2), or pancreatitis. Adherence to FDA guidelines and safety protocols ensures that semaglutide is prescribed judiciously to those who can benefit from its weight loss effects while minimizing potential risks.

Side Effects of Semaglutide

Semaglutide’s side effects tend to be minor and centered on the digestive system — not surprising, since that’s where the medication has some of its greatest effects. Many users experience some nausea, constipation, diarrhea, or generalized abdominal discomfort. Some people may also experience dizziness, headaches, and fatigue. It’s also possible to become dehydrated if you forget to eat or drink while on the medication.


To minimize side effects, you can expect to start on a low dosage of semaglutide, with your dosage increasing monthly as you get used to the medication.

In rare cases, some people may experience pancreatitis or a paralysis of the stomach or intestines.

Why Is Semaglutide Such a Game-Changer?

When the National Institutes of Health reclassified obesity as a disease in 1998, the question was raised as to how it could be treated. While many people are able to lose weight through the combination of exercise and controlling their food intake, other people’s bodies won’t allow that to happen. In these cases, medical intervention can make a big difference. That’s where semaglutide comes in.

Semaglutide enables you to lose weight without extreme behavior modification (though certainly your weight loss will be enhanced by healthy eating and regular exercise). For many people, this medication is the true game-changer they’ve been waiting for. And with research continuing, you can expect to see continued improvements and advancements in the field of medical weight loss. (For example, studies are ongoing to see how semaglutide could be successfully delivered via pill form rather than injection.)

Should Semaglutide Be Part of Your Weight Loss Journey?

Semaglutide could be the true game-change you’ve been looking for as well. Because this is indeed a type of medical weight loss, it’s important to only pursue this medication under the auspices of a licensed health care practitioner. We pay attention to your medical history, your personal goals, your current health, and your family medical history when determining whether this is an appropriate weight loss path for you to take. We look at your weight and your weight loss goals in the context of your entire hormonal health, and we work with you to find the right solutions.

We also want you to be aware that taking semaglutide is a long-term commitment. If you stop taking this medication, you can expect your cravings to return, and you’re likely to regain at least some of the weight you’ve lost. On the flip side, however, we keep a close eye on the most recent developments in medical weight loss, so we can help you shift to a different form of treatment if advisable.

Through its ability to regulate your appetite, to enhance the rate at which you burn energy, and to slow the emptying of your stomach, semaglutide could make a real difference in your weight loss journey. 

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