Hundreds of thousands of people worldwide are taking drugs like Ozempic to lose weight. But what do we actually know about them? This month, The Conversation’s experts explore their rise, impact and potential consequences.
Author
Clare Collins
Laureate Professor in Nutrition and Dietetics, University of Newcastle
Obesity medication that is effective has been a long time coming. Enter semaglutide (sold as Ozempic and Wegovy), which is helping people improve weight-related health, including lowering the risk of a having a heart attack or stroke, while also silencing “food noise“.
As demand for semaglutide increases, so are claims that taking it is “cheating” at weight loss or the “easy way out”.
We don’t tell people who need statin medication to treat high cholesterol or drugs to manage high blood pressure they’re cheating or taking the easy way out.
Nor should we shame people taking semaglutide. It’s a drug used to treat diabetes and obesity which needs to be taken long term and comes with risks and side effects, as well as benefits. When prescribed for obesity, it’s given alongside advice about diet and exercise.
How does it work?
Semaglutide is a glucagon-like peptide-1 receptor agonist (GLP-1RA). This means it makes your body’s own glucagon-like peptide-1 hormone, called GLP-1 for short, work better.
GLP-1 gets secreted by cells in your gut when it detects increased nutrient levels after eating. This stimulates insulin production, which lowers blood sugars.
GLP-1 also slows gastric emptying, which makes you feel full, and reduces hunger and feelings of reward after eating.
GLP-1 receptor agonist (GLP-1RA) medications like Ozempic help the body’s own GLP-1 work better by mimicking and extending its action.
Some studies have found less GLP-1 gets released after meals in adults with obesity or type 2 diabetes mellitus compared to adults with normal glucose tolerance. So having less GLP-1 circulating in your blood means you don’t feel as full after eating and get hungry again sooner compared to people who produce more.
GLP-1 has a very short half-life of about two minutes. So GLP-1RA medications were designed to have a very long half-life of about seven days. That’s why semaglutide is given as a weekly injection.
What can users expect? What does the research say?
Higher doses of semaglutide are prescribed to treat obesity compared to type 2 diabetes management (up to 2.4mg versus 2.0mg weekly).
A large group of randomised controlled trials, called STEP trials, all tested weekly 2.4mg semaglutide injections versus different interventions or placebo drugs.
Trials lasting 1.3-2 years consistently found weekly 2.4 mg semaglutide injections led to 6-12% greater weight loss compared to placebo or alternative interventions. The average weight change depended on how long medication treatment lasted and length of follow-up.
Weight reduction due to semaglutide also leads to a reduction in systolic and diastolic blood pressure of about 4.8 mmHg and 2.5 mmHg respectively, a reduction in triglyceride levels (a type of blood fat) and improved physical function.
Another recent trial in adults with pre-existing heart disease and obesity, but without type 2 diabetes, found adults receiving weekly 2.4mg semaglutide injections had a 20% lower risk of specific cardiovascular events, including having a non-fatal heart attack, a stroke or dying from cardiovascular disease, after three years follow-up.
Who is eligible for semaglutide?
Australia’s regulator, the Therapeutic Goods Administration (TGA), has approved semaglutide, sold as Ozempic, for treating type 2 diabetes.
However, due to shortages, the TGA had advised doctors not to start new Ozempic prescriptions for “off-label use” such as obesity treatment and the Pharmaceutical Benefits Scheme doesn’t currently subsidise off-label use.
The TGA has approved Wegovy to treat obesity but it’s not currently available in Australia.
When it’s available, doctors will be able to prescribe semaglutide to treat obesity in conjunction with lifestyle interventions (including diet, physical activity and psychological support) in adults with obesity (a BMI of 30 or above) or those with a BMI of 27 or above who also have weight-related medical complications.
What else do you need to do during Ozempic treatment?
Checking details of the STEP trial intervention components, it’s clear participants invested a lot of time and effort. In addition to taking medication, people had brief lifestyle counselling sessions with dietitians or other health professionals every four weeks as a minimum in most trials.
Support sessions were designed to help people stick with consuming 2,000 kilojoules (500 calories) less daily compared to their energy needs, and performing 150 minutes of moderate-to-vigorous physical activity, like brisk walking, dancing and gardening each week.
STEP trials varied in other components, with follow-up time periods varying from 68 to 104 weeks. The aim of these trials was to show the effect of adding the medication on top of other lifestyle counselling.
A review of obesity medication trials found people reported they needed less cognitive behaviour training to help them stick with the reduced energy intake. This is one aspect where drug treatment may make adherence a little easier. Not feeling as hungry and having environmental food cues “switched off” may mean less support is required for goal-setting, self-monitoring food intake and avoiding things that trigger eating.
But what are the side effects?
Semaglutide’s side-effects include nausea, diarrhoea, vomiting, constipation, indigestion and abdominal pain.
In on study these led to discontinuation of medication in 6% of people, but interestingly also in 3% of people taking placebos.
More severe side-effects included gallbladder disease, acute pancreatitis, hypoglycaemia, acute kidney disease and injection site reactions.
To reduce risk or severity of side-effects, medication doses are increased very slowly over months. Once the full dose and response are achieved, research indicates you need to take it long term.
Given this long-term commitment, and associated high out-of-pocket cost of medication, when it comes to taking semaglutide to treat obesity, there is no way it can be considered “cheating”.
Read the other articles in The Conversation’s Ozempic series here.
Clare Collins AO is a Laureate Professor in Nutrition and Dietetics at the University of Newcastle, NSW and a Hunter Medical Research Institute (HMRI) affiliated researcher. She is a National Health and Medical Research Council (NHMRC) Leadership Fellow and has received research grants from NHMRC, ARC, MRFF, HMRI, Diabetes Australia, Heart Foundation, Bill and Melinda Gates Foundation, nib foundation, Rijk Zwaan Australia, WA Dept. Health, Meat and Livestock Australia, and Greater Charitable Foundation. She has consulted to SHINE Australia, Novo Nordisk, Quality Bakers, the Sax Institute, Dietitians Australia and the ABC. She was a team member conducting systematic reviews to inform the 2013 Australian Dietary Guidelines update, the Heart Foundation evidence reviews on meat and dietary patterns and current Co-Chair of the Guidelines Development Advisory Committee for Clinical Practice Guidelines for Treatment of Obesity.
