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Weight Management

The Science of Semaglutide

Duncan Reid: Patient Safety & Professional Services Manager | minute read
weightloss image, woman working out with weights outside

Losing weight and achieving a healthy BMI can sometimes be challenging. Additional medical intervention may be appropriate for people who have found it difficult to lose weight through diet and exercise alone. New treatments have recently been approved for use to support patients living with obesity.

Since its approval for use in the UK under the brand name Wegovy on 4th September 2023, Semaglutide has emerged as a powerful tool in weight management. Understanding the science behind it can help you understand how the medication impacts your body so you can be fully informed.

How Does Semaglutide Work?

Semaglutide belongs to a class of medications called glucagon-like peptide-1 (GLP-1) receptor agonists. GLP-1 is a naturally occurring hormone produced in the gut that is vital in regulating appetite, insulin secretion, and digestion. Here's a breakdown of how GLP-1 functions:

  • Appetite Control: GLP-1 signals the brain to feel satiated, reducing hunger pangs and cravings.

  • Insulin Secretion: GLP-1 stimulates the release of insulin from the pancreas, promoting better blood sugar control.

  • Digestive Slowing: GLP-1 helps slow down the emptying of stomach contents, leading to feelings of fullness for longer.

Semaglutide mimics the effects of GLP-1, acting on these pathways to promote weight loss. This translates to feeling less hungry, eating less food, and ultimately reducing calorie intake. GLP-1 drugs were awarded Breakthrough of the Year in 2023 by Science, making them a hot topic within the weight loss industry, but where did it all begin?

The History of Semaglutide

GLP-1 was first identified in the early 1980s and was initially researched for its role in regulating blood sugar levels. After discovering the effects of GLP-1 on the body, researchers aimed to create GLP-1 receptor agonists - drugs that mimic its effects. 

After initially trialling drugs that mimicked GLP-1 as type 2 diabetes treatments, researchers noticed a secondary outcome that participants were losing weight. Over time, companies then looked to produce drugs that would be effective for weight loss that targeted GLP-1. Liraglutide was the original medication created, followed by treatments that utilise semaglutide and tirzepatide.

What Do the Experts Say?

In 2021, scientists discovered that semaglutide acted similarly to liraglutide but remained intact in the body for longer which produced more significant results. Following rigorous tests, in September 2023, semaglutide was approved as a weight loss treatment in the UK under the brand name, Wegovy. This marked a significant advancement in the field of obesity treatment, offering a more effective and long-lasting solution compared to previous medications. 

Robert Kushner, obesity researcher and professor at Northwestern University Feinberg School of Medicine, describes semaglutide as a valuable advancement in the weight loss industry. He says, "It's the first time that we have seen this magnitude of weight loss compared to current medications on the market for obesity. It's 1.5 to 2 times more effective than currently available drugs."

Research Behind Semaglutide's Effectiveness

Clinical trials have played a crucial role in establishing semaglutide's effectiveness for weight loss. Studies like the STEP trials have demonstrated fantastic results, for example in STEP 1 when comparing a group administering semaglutide to a placebo group, those using semaglutide injections had a mean 14.9% decrease in body weight after 68 weeks compared to a 2.4% reduction for the placebo group. 

Fast forward to STEP 5, and this research looked into the effects of semaglutide over two years. Results came back very similar to the first study, from baseline to week 104, the mean change in body weight was -15.2% for participants in the semaglutide group compared to -2.6% in the placebo group. 

Semaglutide Side Effects

For anyone clinically suitable for weight loss injections who may be considering them, we'd recommend familiarising yourself with the potential side effects so you can plan to manage them. Positively, most participants in semaglutide research who experienced side effects described them as mild-to-moderate. 

Very common side effects include:

  • Headache 

  • Feeling sick (nausea) 

  • Being sick (vomiting) 

  • Diarrhoea 

  • Constipation 

  • Stomach pain 

  • Feeling weak or tired

Although rare, there are some individuals who experience more serious side effects like pancreatitis and acute gallstone disease/cholelithiasis.For more information on the side effects of semaglutide, read through the patient information document.

How Long Do Semaglutide Side Effects Last?

Most common side effects do not require medical attention and should subside within a few days or weeks as your body becomes accustomed to the medication. If you are worried about side effects, raise your concerns with your pharmacist, GP or a healthcare professional. It may be beneficial if you are experiencing negative effects to discuss moving your dosage to a lower strength until these side effects pass.

How to Use Semaglutide for Weight Loss

Now we know how effective the drug is for weight loss, how do you go about using it? Semaglutide, licensed as a weight loss treatment under the brand name Wegovy, is self-administered as an injection and comes in pre-filled injection pens. 

To use effectively, Wegovy is first administered as a 0.25mg once-weekly injection, then increased progressively in steps up to 2.4 mg once weekly by the end of 16 weeks. Injections can be inserted into fatty areas on the body including your upper arms, stomach or upper legs. Before you use the pen for the first time, ask your pharmacist how to use it.

What Is the Difference Between Ozempic and Wegovy?

You may have heard of Ozempic and Wegovy being used interchangeably, as they both share the same active ingredient - semaglutide. However, these medications have different purposes. Ozempic is specifically for individuals who have type 2 diabetes, whereas Wegovy is for those living with obesity and weight-related health conditions. Wegovy is suitable for individuals who either have obesity (BMI over 30) or are overweight (BMI higher than 27) and have a weight-related health condition such as high blood pressure.

Wegovy at Pharmacy2U

Semaglutide represents a significant breakthrough in weight management, showcasing excellent results in research so far. Want to know more about whether you could be suitable for this weight loss treatment? Explore our Wegovy treatment page to see if you might be a good fit for semaglutide. 

Pharmacy2U offers a variety of weight loss treatments, including injections and pills. Complete our easy-to-follow, comprehensive consultation for us to help you navigate your options and determine if a Wegovy prescription is the right approach for you. All treatments and administration of weight loss drugs are subject to GP review, which can be completed through our Online Doctor service.