What Are Weight Loss Injections?

Weight loss injections are prescription medications administered through injections that help people lose weight. By mimicking a hormone that regulates appetite and blood sugar levels, these injections aid in weight loss by suppressing appetite, increasing feelings of fullness and delaying gastric emptying. Commonly prescribed weight loss injections include Ozempic, Mounjaro and Wegovy. ​​These medications are not intended to help slim people remain slim. They are designed for individuals who are struggling to lose weight.

A major breakthrough in weight management was the development of GLP-1 mimic injections. These were first approved for type 2 diabetes because they boost insulin release in response to blood sugar. A significant side effect was weight loss, which led to their later approval for obesity treatment.

What Do Weight Loss Injections Do?

The most important factor to reduce weight is to manage your appetite. GLP-1 is a hormone that makes us feel full faster. Weight management injections imitate GLP-1. This leads to eating less and losing weight naturally. They also help regulate blood sugar by increasing insulin secretion. Some newer medications, such as Mounjaro, also activate a second hormone called GIP, which blocks fat gain and helps preserve muscle during weight loss. These injections are usually given once a week, making them more convenient than older daily options.

How Do You Use Weight Loss Injections?

Weight loss injections come in pre-filled pens. You attach a fresh needle for each injection. The common sites are the abdomen or inner thigh. Pinch a bit of fat and inject the dose you have been prescribed. It is vital to start with a low dose. Then slowly increase as your body tolerates it. People using these medications for weight loss often need higher doses than those using them for diabetes.

What Are the Side Effects of Weight Loss Injections?

Weight loss injections share similar side effects, most of which affect the gut. Common side effects include:

  • Nausea
  • Vomiting
  • Constipation
  • Diarrhoea

The main effect you’ll notice is appetite suppression; you’ll feel full much more quickly. However, it’s important to discuss any persistent or severe symptoms with your healthcare provider.

Types of Weight Management Injections

Two commonly prescribed weight loss injection options include:

  • Wegovy uses semaglutide, which activates the GLP-1 hormone to reduce appetite and increase fullness.
  • Mounjaro uses tirzepatide, which activates both GLP-1 and GIP hormones. This promotes fat loss, blocks fat gain and preserves muscle during weight loss.

How to Choose Between Wegovy and Mounjaro

Both Mounjaro and Wegovy are effective weight loss medications on their own. However, with Mounjaro, muscle wastage is prevented, unlike with Wegovy. Maintaining muscle during weight loss is essential for preventing bone damage and weight regain as a result of rapid weight loss.

According to a new study published by the New England Journal of Medicine in May 2025, Mounjaro (tirzepatide) caused more weight loss compared to Wegovy (semaglutide). Participants taking Mounjaro lost an average of 20.2% of their body weight, while those on Wegovy lost 13.7%.

Your choice between the two depends on your medical history, side effect tolerance and cost.

Weight Loss Injections at The Oakley Medical Practice

At The Oakley Medical Practice we offer private weight loss injections, including Wegovy and Mounjaro, as part of our weight management services in Birmingham. As a doctor-led team and CQC-registered provider, we ensure that every weight loss programme is medically supervised.

Unless you also combine injections with a calorie-controlled diet, healthy eating and regular exercise, the weight is likely to return once the treatment ends. That’s why we offer weight reduction treatments combining prescription injections with the Alevere Nutrition Plan for safe, effective weight loss. This approach helps preserve muscle mass during fat loss and supports your overall health.

Coming to a private GP to start your weight loss journey means our doctor is always on hand for reassurance and safety.

Book your weight management consultation today and start a medically supervised journey to lasting health and confidence.