Some truths about weight-loss injections like Ozempic and Mounjaro

Irish Examiner

02-05-2025

In what feels like the biggest health craze in years, weight loss jabs like semaglutide (Ozempic and Wegovy) or tirzepatide (Mounjaro) have exploded in popularity.
GP registrar Dr Jack Mosley says his father, the late BBC presenter Dr Michael Mosley, had been worried about the potential impact of the newly emerging medications.
'He could see they were a groundbreaking treatment because there's such a long history of all these slightly dodgy pills and potions that they used in the past,' says the 32-year-old. 'But he was still concerned about how they were currently being managed, and the fact that there is a wild west of online pharmacies.'
One significant concern is that 'these drugs were designed for people who have a BMI over 30 or women over 27 with an obesity-related disease. These drugs were not made for a quick fix to lose a few kilos', says Mosley.
He has just released his first book, Food Noise, on the subject and how to live healthily alongside the drugs. Here's what he wants people to understand about the weight loss medication:
They aren't a magic fix: 'They do dramatically reduce your appetite, they reduce your cravings, and which ultimately leads many people to eat less,' says Mosley. 'But I think people just see these drugs as a magic fix. So they take the injection, and they kind of just go along with their lives, and they don't make the lifestyle changes. They don't appreciate them as these powerful drugs they are.'
Potential side effects: Mosley says the flip side to losing weight might also include symptoms such as nausea, vomiting, diarrhoea and constipation — 'These all occur because of the way it can slow down the bowel.' He adds: 'And I think if people continue to eat how they did before, they'll actually get much more significant side effects, which could lead to poor compliance.'
Malnutrition is a risk: According to a famous study in The Lancet, some 50% of people living with obesity in America have some degree of micronutrient deficiency. 'We're overfed and undernourished,' says Mosley. 'People need to make sure they are eating nutritious meals [on weight-loss medication].
'You may even lose weight on a processed junk food diet [on the drugs] but the problem is, if you're just eating a smaller bowl of chips, you may end up with downstream consequences — some degree of malnutrition.'
You might lose muscle: 'The fact that we're eating a lot less can lead to muscle loss — 25% to 40% of the weight people lose in the studies is lean body mass, and a big component of that is muscle.
'Muscle is so important. It's a major predictor of a long lifespan, but also health span,' he says. 'If you want to stay independent in later life, and be able to get about easily and to do things for yourself, it's so important, it reduces your risk of falls. It also sucks up a lot of the sugar in our bloodstream. So is it very protective of diabetes.'
Exercise is key: 'Staying active so important while you're on these drugs,' says Mosley, who particularly recommends resistance training. 'This can be as simple as doing it from the comfort of your own home. Find a seven-minute workout online, which may involve a few press-ups and squats. You can just use your own weight or resistance bands. Protecting your muscles is so important when you're on these drugs.'
Eat a nutrient-rich diet: Evidence points to a Mediterranean-style diet being a healthy way to eat on weight-loss medication. 'This is a diet rich in olive oil, nuts, seeds, oily fish, fruit and veggies and pulses, like chickpeas and lentils. It's got plenty of protein, healthy fats, fibre and micronutrients.
'If you do follow this kind of more nutritious, filling way of eating, then not only will you feel better, but you may lose more weight while you're on [the drugs] and also, if you do come off them, it should be more sustainable that you'll be able to keep the weight off.
Watch for emotional eating: "The weight-loss drugs can reduce our appetite and our cravings, but they're not necessarily going to address things like our emotional hunger,' says Mosley. To tackle it, Mosley advises trying to reduce stress. 'Do things like increasing your exercise — strength training is really good for reducing stress levels. Meditation and mindfulness are proven to be incredibly useful. And I think the final thing is actually changing your diet.'
How not to put weight back on afterwards: When people come off the drugs, they are likely to put back on the weight they've lost, he says. 'We know from some of the studies that people can put on two-thirds of the weight they lost within the first year.'
He explains: 'I like to think of these drugs as these noise-cancelling headphones. You put them on, your cravings reduce, your appetite reduces and you go about your day not as tempted by all these foods. But then, when you take these noise-cancelling headphones off, that food noise can return with a vengeance. That's why it's so important to make some of these [lifestyle] changes whilst you're taking the medication.
'It's so important to try and control the food environment because I think willpower is somewhat overrated,' he says.
Food Noise: How Weight Loss Medications And Smart Nutrition Can Silence Your Cravings by Dr Jack Mosley is published by Short Books, €19