Which Weight Loss Injection Is Best? Our Family Doctor Explains

If you have been exploring weight management options, you may have heard of semaglutide and tirzepatide. Both are new medications shown to help people lose weight, but it can be confusing to know how they differ, how they work, and which might be right for you. As a family doctor, my goal is to help you understand these medications so you can make informed decisions about your health.

Semaglutide and tirzepatide are injectable medications used for weight management in people with obesity or those who are overweight with weight-related health conditions like high blood pressure, type 2 diabetes, or high cholesterol.

• Semaglutide belongs to a group of medicines called GLP-1 receptor agonists.

• Tirzepatide is a dual GIP and GLP-1 receptor agonist.

Both medications are given as once-weekly injections, and both work by helping you feel fuller for longer, reducing hunger, and slowing stomach emptying. They also help your body use insulin more effectively, which can support healthier blood sugar levels.

Semaglutide works by mimicking a natural hormone in your body called GLP-1, which helps regulate your appetite and food intake. By acting like this hormone, semaglutide helps reduce cravings and increases feelings of fullness, so you eat less and feel satisfied sooner.

Tirzepatide also mimics GLP-1 but has the added action of mimicking another hormone called GIP (glucose-dependent insulinotropic polypeptide). This dual action appears to enhance the effects on blood sugar control and appetite regulation, potentially leading to greater weight loss.

Clinical trials show that semaglutide can help people lose around 15% of their body weight on average when combined with lifestyle changes. For example, a person weighing 100 kg may lose around 15 kg over time.

Tirzepatide has shown even higher average weight loss in clinical trials, with some people losing around 20% of their body weight. In the same example, this could mean a weight loss of around 20 kg for a person weighing 100 kg.

It is important to remember that individual results vary, and these medications are most effective when combined with a healthy diet, regular physical activity, and other lifestyle changes.

Both semaglutide and tirzepatide can have side effects, mainly related to the digestive system. These may include:

• Nausea

• Vomiting

• Diarrhoea

• Constipation

• Stomach pain

These side effects often improve over time as your body adjusts to the medication. Starting at a lower dose and gradually increasing can help reduce these effects.

Rare but serious side effects may include pancreatitis (inflammation of the pancreas) and gallbladder issues. If you experience severe stomach pain, persistent vomiting, or yellowing of the skin or eyes, you should seek medical advice immediately.

It is important to know that tirzepatide is currently more expensive than semaglutide in most countries. While tirzepatide may offer higher average weight loss for some patients, the cost difference can be significant, especially for long-term use. If cost is a factor in your decision-making, this is worth discussing with your doctor when considering your options.

Both medications are taken as weekly injections, but they have different starting doses and dose adjustment schedules, which you should discuss with your doctor and decide together based on your lifestyle and the target weight. 

Neither medication is suitable for everyone. They should not be used during pregnancy or by people with certain medical conditions, including a history of specific thyroid cancers. Your doctor will review your medical history to ensure these medications are safe for you.

Choosing between semaglutide and tirzepatide depends on your health history, weight loss goals, how your body responds, availability, and cost.

• Semaglutide may be a suitable option if you are looking for effective weight management and prefer a medication with a longer track record for weight loss.

• Tirzepatide may be considered if you also have type 2 diabetes or if you and your doctor are aiming for potentially greater weight loss and are comfortable with the higher cost.

Both medications can be highly effective tools, but they are not quick fixes. They work best when combined with realistic, long-term lifestyle changes, including a balanced diet, regular physical activity, good sleep, and stress management.

Obesity is a complex, long-term health condition, and there is no one-size-fits-all approach to treatment. Medications like semaglutide and tirzepatide offer new tools to help manage weight and improve overall health, but they are just one part of a broader plan.

If you are considering medical options for weight management, I encourage you to book an appointment to discuss your health goals and medical history. Together, we can explore whether semaglutide, tirzepatide, or another approach would be the best fit for you. We help you: 

• Understand your options

• Create a sustainable plan

• Feel supported on your journey