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The science behind the hype: Weight-loss injections

Liz Blamire

21st March 2023

This morning I Googled 'semaglutide', I then searched YouTube and The Conversation with the same simple search term. I was inundated with results.

What is semaglutide?

To help explain this to you, I went straight to a source that I can trust - the National Institute for Health and Care Excellence (NICE).

Semaglutide binds to, and activates, the GLP-1 (glucagon-like peptide-1) receptor to increase insulin secretion, suppress glucagon secretion, and slow gastric emptying.

In a nutshell:

  • Increasing insulin secretion will make your cells more effective at taking up the glucose in your blood.
  • Suppressing (slowing down) glucagon secretion, reduces the production of glucose by your pancreas.
  • Slowing gastric emptying, means your stomach takes longer to empty, which results in feeling fuller for longer.

If you are studying anatomy and physiology or human biology, it won't surprise you that semaglutide is actually a drug used to treat type 2 diabetes.

The reason that semaglutide has proven to be effective in aiding weight loss is because it keeps you feeling fuller for longer by slowing down stomach emptying but it also controls appetite because the feeling of being full, supresses appetite.

Is semaglutide the answer to the obesity crisis?

The evidence for the effectiveness of semaglutide for obesity is good. In research trials, people lost on average 15% of their bodyweight when prescribed semaglutide. However, we also know that when they stop taking it, their appetite quickly returns and may be stronger than before. In the original study, many people regained the weight they had originally lost.

Semaglutide is a drug and therefore it has side effects. For example, it can cause nausea, diarrhoea or constipation and vomiting. It can also cause rarer but more serious side effects such as inflammation of the pancreas, gallbladder issues and kidney failure. It is also contraindicated for people with certain medical or family histories and some people may be allergic to it.

For best results semaglutide must also be used as part of a treatment plan, because it works best when individuals also change their diet and exercise habits. In the UK, the drug will only be available on prescription, via NHS weight-loss services.

What semaglutide doesn't do

We know that obesity is complex. The causes of obesity are multifactorial, linked to health inequalities such as access to a nutritious diet, safe spaces for exercise, even gas and electricity to store and cook food and many more factors. Thus, solutions also need to be multifactorial. We also know that more and more children are becoming obese and semaglutide is not approved for use in children

Weight-loss drugs can certainly help individuals manage their weight but it won't solve the obesity crisis.

Read more:

Wegovy: what you need to know about this weight loss drug

Ozempic helps weight loss by making you feel full. But certain foods can do the same thing – without the side-effects

Weight-loss: Are injections the answer to tackling obesity?

Liz Blamire

Liz is the current tutor2u subject lead for Health and Social Care. She is a former NHS midwife, who has worked in community, birth centre and acute hospital settings. Liz is an SSAT Accredited Lead Practitioner, who has taught Health and Social Care in FE and secondary schools, where she was a successful HOD. Liz is an experienced senior examiner and author.

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