Doctors explain how weight-loss injections work. By Lisa Salmon

Appetite-suppressing drugs are increasingly becoming a hot topic of conversation.

Weight-loss injections, like Wegovy and Saxenda, are available on the NHS. If prescribed alongside a reduced-calorie diet, increased physical activity, and behavioral support, people taking them can lose more than 10% of their body weight after a year, according to the National Institute for Health and Care Excellence (Nice).

The Ozempic drug, however, can only be prescribed for patients with type 2 diabetes and isn’t licensed as a weight-loss drug in the UK or the US, although the UK government acknowledges: “It is not authorized for weight-loss, but it is used off-label for that purpose.”

Dr Alexis Missick from UK Meds warns against the casual use of diabetes drugs for weight loss without understanding its potential risks. Ozempic can cause gastrointestinal side effects despite its effectiveness in weight loss due to appetite-suppressing properties.

“It’s crucial to approach Ozempic with a comprehensive understanding of its potential side-effects and to use it under strict medical supervision and guidance.”

But what about the weight-loss injections licensed in the UK, like Wegovy, Saxenda, and the recently approved Mounjaro?

How do the injections work?

Dr. Babak Ashrafi from Superdrug Online Doctor explains that GLP-1 is released by the guts when we eat, and weight-loss injections that mimic the hormone are called ‘GLP-1 analogs’.

He explains that the small and large intestines produce GLP-1, a hormone that stimulates insulin release from the pancreas and plays a vital role in regulating blood sugar levels. “GLP-1 slows gastric emptying and signals satiety to the brain, contributing to fullness and satisfaction after eating.

“Synthetic analogues of GLP-1 replicate the effects of the natural hormone telling your brain you are full and satisfied.”

Who can benefit from weight-loss injections?

Nice has issued guidance for semaglutide injections like Wegovy, recommending them for adults with at least one weight-related condition and a body mass index (BMI) of at least 35. In some cases, those with a BMI of 30 can access the injections.

“They are typically recommended for people who have not achieved sufficient weight loss through diet and exercise alone, to improve their overall health and quality of life,” says Ashrafi.

How long do you take the injections for?

This varies from person to person, but the Nice guidelines say semaglutide should be used for a maximum of two years.

Noticeable weight changes are common in the first six months, says Ashrafi. If you haven’t lost 5-10%, the medication may not be right for you. It’s advisable to discontinue it and explore alternative treatment options.

According to Nice, people on the weekly injections saw their weight drop by 12% on average after 68 weeks.

What are the side effects?

The drug targets the gut and can cause nausea, heartburn, and constipation, but these side effects generally improve with time and hydration.

“It is common for people to unintentionally reduce their daily fluid intake as a result of having a reduced appetite. This can result in feeling bloating, irregular bowel movements and stomach irritation,” he explains.

The medication can cause headaches and fatigue, impacting the central nervous system. Fluctuations in blood sugar levels resulting from changes to insulin and glucagon levels may also contribute to these symptoms.

“Eating small nutritious meals regularly instead of larger meals three times a day is a great way to combat this.”

Anything else you need to know?

In March, Wegovy became available for NHS prescriptions.

The weekly injection delivers an appetite-suppressant drug.

Academics and charities reacted to the news. Dr. Stephen Lawrence warned about medication. It’s not a quick fix. It’s not a replacement for a healthy lifestyle. A healthy lifestyle includes physical activity. It also includes healthy eating.

Eating disorder charity Beat also raised concerns about Wegovy.

Alex Miras praised Nice’s decision as a pivotal move for treating obesity.