New drugs are transforming weight loss - but not for everyone

GLP-1s like Wegovy are transforming weight loss, but behind the hype, not everyone responds as they hope.

Caption:GLP-1s like Wegovy and Mounjaro don't work for everyone, but we don't hear much about the non-success stories. Photo credit:RNZ composite/ screenshot

Imagine you struggled with your body weight for years, but overseas, there was a miracle drug pitched as the silver bullet for obesity.

Oprah Winfrey, arguably the face of yo-yo dieting for decades, raved about the 23 kilos she lost. Former tennis champion Serena Williams is such a fan that she became a brand ambassador of US telehealth provider focused on the drugs known as GLP-1s and names like Wegovy and Mounjaro. Study after study demonstrated their remarkable, far-reaching effects that went far beyond weight loss.

You watched this story play out for years from your small island nation where the medication wasn’t available. As soon as one of the drugs came on the market - Wegovy launched here on July 1 last year - you got a prescription and forked out close to $500 a month over eight months. Your total weight loss: three kilos.

That was the reality for Janet, a 69-year-old from the Bay of Plenty.

“You get celebrities abusing these drugs, people who really don't need to lose weight, who are losing far more than they need to," she told RNZ.

“And so people think that, ‘Oh, if we just put people who are obese onto these drugs, we'll solve the problem', but it doesn't work the same for everybody.”

However, there is roughly a one in ten chance that anyone taking a GLP-1 will turn out to be a non-responder, like Janet. A small percentage of patients can also experience extreme side effects such as diarrhoea, nausea and tiredness, forcing them to discontinue despite positive weight loss results. These are two issues that weight loss specialists say can be improved with wraparound support from doctors who specialise in weight loss and dietitians.

Like most people, Janet’s journey with weight is complicated. It was up and down for her adult life. She tried Weight Watchers, cut calories to 800 a day, exercised and eventually landed on a low carb, high protein diet.

In 2023, she tried Saxenda, an early version of today’s GLP-1s where users typically lose about a third of weight of Wegovy users. The daily injectable - compared to Wegovy’s weekly injection - helped her lose about six kilos before trying Wegovy. All in, she spent $12,610 on weight loss medications to lose nine kilos, less than half her goal.

Now, an even more successful GLP-1, Mounjaro, is available in New Zealand, but at about $800 a month, Janet is tapping out of her experiment with GLP-1s.

"I'm still working part-time, but I will be retiring shortly, and I won't be able to afford it anyway.”

Between two and three percent of patients at Dr Gerard McQuinlan’s practices in Wellington and Tauranga are non-responders. A loss of around 15 percent of body weight is the norm on Wegovy. Those considered non-responders lose less than five percent.

The medical field is still narrowing in on why some people don’t respond, but solid theories have developed, says McQuinlan, a GP who specialises in weight loss.

Some people might develop a receptor resistance to the hormone in GLP-1s, he says. This could be overcome by giving them a higher dose of the drug.

“But we don't, and we can't because… it is not funded, so it will cost them a fortune, unfortunately.”

Underlying attention deficit hyperactivity disorder (ADHD) in a patient could be another cause, says McQuinlan. The prevalence of obesity in adults with ADHD is significantly higher than in the general population.

“When you put those patients on a GLP, and they don't respond, it's because they can push through the [appetite] suppression."

If a patient comes in with an ADHD diagnosis, he typically puts them on the ADHD medication Vyvanse first. Others have discovered they have ADHD because they didn’t respond to a GLP-1, he says.

If patients don’t respond to Wegovy, they could try the more costly Mounjaro, which has improved weight-loss results and reduced side effects, says McQuinlan. Only a handful of his patients have stopped taking a GLP-1 due to side effects.

Side effects will likely be worse in the first 16 weeks of taking the medication, says Dr Maria Casale, a dietician at Massey University. Those taking a GLP-1 like Wegovy should slowly increase their dose rather than going straight to the maximum, she says.

Eating regular meals along with keeping up fibre intake will help with gastrointestinal issues, says Casale. Doctors and dietitians can also prescribe medication that can also help, such as laxatives to help with constipation and anti-diarrhoea medication.

“We have a lot of dietary strategies to help with nausea, similar to how you would manage things like morning sickness, for example.”

Intense side effects and lacklustre weight loss are two reasons why patients should seek the support of registered dietitians or weight loss specialists, Casale added.

Alison, a Christchurch woman in her 50s, lost 20 kilos over seven months using Wegovy, but it was not easy. She is slowly weaning herself off the medication because of the cost and how it makes her feel. Alison faces an uphill battle, with between 21 to 23 percent of semaglutide and tirzepatide users putting all their lost weight back on within 24 months of discontinuing medication. (Semaglutide is the active ingredient in Wegovy, and tirzepatide is the active ingredient in Mounjaro).

Alison described the side effects in the first six months as a daily grind, including constant nausea where she had to force herself to eat, extreme lethargy, and her hair falling out in clumps.

“My mind, my body has had enough, and I don’t want to keep putting my body through that.”

Get weekly Life highlights

Coverage

Our editors pick the best of food, arts, culture and lifestyle. Delivered straight to your inbox every Saturday.

More from Wellbeing