For the past three years, our friends and colleagues have been shrinking all around us. You probably know someone who is ‘on the pen’: an estimated 1.6million people in the UK – most of them middle-class, middle-aged women according to a survey this week – are now using injectable weight-loss drugs.

The original GLP-1s, Ozempic and Wegovy, were closely followed by the more sophisticated, pricier Mounjaro, on which users can lose up to 20 per cent of their body weight.

So effective have these drugs proved that Weight Watchers filed for bankruptcy last summer, and Marks & Spencer has just instituted a jab-friendly food range.

But here’s a thing that isn’t talked about so much: Wegovy and Mounjaro don’t work for everyone. Studies have found that nine to 15 per cent of participants do not lose a ‘clinically significant’ amount of weight on these drugs, due to genetics, hormones, or simply being unable to tolerate the side-effects.

In 2023, Boris Johnson shared how his jab-induced nausea saw him frequently ‘talking to Ralph on the big white phone’ – and he eventually quit. Last month, broadcaster and baker Prue Leith wrote in the Daily Mail of her own failure to lose a single pound on Mounjaro despite its savage suppression of her appetite.

My own experience with Mounjaro, like Prue’s, was brutal and brief. At the age of 56, I weighed around 11st 9lb (I’m 5ft 2in). The rapid weight gain in my late 40s was caused by the antidepressants prescribed after the bitter end of my marriage; the menopause probably didn’t help.

Even after my recovery and withdrawal from the pills, the pounds proved hard to shift. A healthy diet and regular exercise routine worked to some degree, but by autumn 2024, I had hit a wall.

My BMI was stuck somewhere between an ‘overweight’ 29, and 30, the first rung of ‘obese’. Though I was pretty fit and some of the weight was muscle – at least, that’s what I told myself – it never feels good to be associated with the word ‘obese’.

And so, in the early weeks of Mounjaro’s launch in the UK, I resolved to try it.

I felt that an in-person clinic would prove more legitimate than an online offering. But, as I learned to my cost, just because someone bears the title of ‘doctor’ and has a London High Street premises, it does not mean they are ethical.

So when the handsome young GP assured me the usual 2.5mg starting dose of Mounjaro would be a ‘waste of time’, and I should jump straight to 7.5mg, I took him at his word. I later discovered there was a nationwide shortage of the 2.5 starter dose.

The first week, I was flattened with nausea. I threw up several times, and completely lost my appetite. It was weird, and more than a little scary. A nibble of toast and a spoonful of soup was pretty much all I could manage all day. One lunchtime, I insisted on moving my untouched jacket potato to the next café table so I no longer had to look at it: food had become my enemy. I also had terrible constipation.

In ten days I lost 5lb. But there was no way I could continue going through that, so I swore off the drug for ever.

When I started feeling better, I amped up my diet and exercise routine. I now follow the Mediterranean diet, eating lots of fruit, veg, nuts, berries, and lean meat. I do weekly boxing and resistance sessions with a trainer, and walk for an hour a day, often with a heavy backpack.

A year on from my Mounjaro fail, I weigh half a stone less than before I tried it. I am aware I was naive and unlucky with my Mounjaro experience: I may have done perfectly well on a lower starting dose and might now be skipping about in a perfect size 10. But this experience has told me weight loss drugs are not for everyone.

Here, three other weight-loss drug refuseniks explain why it failed for them, too, and Dr Kieran Seyan, Chief Medical Officer at Lloyds Pharmacy Online Doctor, gives his expert verdit .

‘I knocked myself out and ended up in A&E’

Clare Martin, 40, is the director of a marketing agency. She lives in Westcliff in Essex with her husband and her nine-year-old son.

Weight lost on jabs: 42lb (3st)

Money spent: £1,000 (£23.80 per lb of weight lost)

Towards the end of 2024, my weight had crept up to 13st 5lb (I’m 5ft 6in) and I was nudging a size 18. At home, I used fresh ingredients, but I ate out a lot, and had fallen into the habit of drinking a glass or two of wine every night – more at weekends.

My jeans felt tight, and I couldn’t wait to change into pyjamas when I got home from work.

Then, a friend of mine confided that she was using Wegovy and that her husband was on Mounjaro. He appeared to be losing more weight than she was, so I made a snap decision: if you’re losing weight this way, so can I.

I had a consultation with an online clinic, and started on 2.5mg of Mounjaro in November 2024.

I was excited. ‘This will be the answer to everything,’ I thought. But I was also a bit apprehensive and ashamed – weight-loss drugs were still a bit taboo back then –so I took my first jab in the loos at work, before anyone arrived.

Even so, I decided the £199 a month was worth it.

The sickness kicked in after my second jab the following week – a constant queasiness. The best way to describe it is like morning sickness but the nausea lasted all day. As I went up the doses of Mounjaro, eventually hitting 7.5mg in month four, the sickness would get worse. I’d throw up 24 hours after each injection, as well as spending three or four hours on the loo with an upset stomach.

By the end of the fourth month, I had lost an incredible two stone, but the constant feeling of sickness was really getting me down, so I vowed to pack it in as soon as I’d finished what I’d paid for.

In February 2025 I was recovering from the flu when I took my scheduled 7.5mg dose. A day or two later, I went to the bathroom, started to feel dizzy and knocked myself out on the sink.

My father-in-law rushed me to the hospital. Thank God, the A & E doctors gave me the all-clear. I didn’t tell them I was on Mounjaro, but I did discover my blood sugar was low. And so I vowed to take a break from the drug. To this day, I’m convinced my fainting was due to over-rapid weight loss.

By the end of the month, my blood sugar levels had normalised – but so had my eating, and my weight was starting to rebound.

Disappointed, I vowed to have one last go on Mounjaro so I could reach my target weight of 10st 5lb, which I did in late September. But I hated the way it made me feel constantly sick. I was so fed up it began to affect my work and home life. It was a relief to finally stop.

Inevitably my weight has started to creep up now I’m off it. I’m trying to keeping the weight off with a diet high in salads, fruit and vegetables, and also trying a gut health supplement called Elcella. It’s so good to feel strong, healthy – and not to have to pay for the privilege of feeling sick.

Dr Seyan says:‘Side-effects such as nausea, diarrhoea and constipation occur because the medication slows gastric emptying and alters gut hormone signalling. For many patients symptoms improve as the body adapts.

‘But when the dose is increased, particularly if escalated too quickly, the side-effects can get worse.

‘In more severe cases, dizziness or fainting can occur, often related to a very low calorie intake, dehydration or a drop in blood pressure rather than the medication itself. Patients who find side-effects difficult to tolerate should speak to their doctor as soon as possible.’

‘I lost more weight at a slimmers’ group’

Annelies Bristow, 40, is a chartered surveyor who lives in Hampshire with her husband and seven-year-old son.

Weight lost on jabs: 13lb

Money spent: £1,200 (£92.31 per lb of weight lost)

Looking at this picture of me you’d think I had nothing to worry about, but I’ve spent my life struggling with my weight. Keto, the 5-2, the juice diet, I have tried them all. By the time I read about Ozempic in 2022, I weighed 18st – a lot for my 5 ft 3in frame and I was desperate to try anything that would help me shift it. Until around 10 years ago, I was a fit size 10. 

But after marrying Ed, my second husband, I started putting on the ‘love weight’. We went out for lots of meals and loved drinking wine with nibbles on the side. Sitting around during Covid didn’t help, but my weight really rocketed after I came off the Pill to try for a baby. It turned out I had polycystic ovary syndrome (the treatment for which is to be on the Pill) and an underactive thyroid.

 In the November, I visited an online clinic, who put me on the starter dose of Ozempic. I barely had any side-effects, but as I went up the doses nor did I really have any weight-loss ‘effects’, either.

Perhaps my desire to drink wine went down a little bit, but my appetite stayed more or less the same. By June on Ozempic, I’d lost just under a stone, which is disappointing when you are 18st and paying £200 a month.

In June 2024, there was a national shortage of Ozempic, and I guess in some ways I saw this as an excuse to quit. I knew I still had weight to lose, so instead I went down the old-fashioned route and joined Slimming World, on the recommendation of my GP.

Taking a weight-loss jab is quite a lonely pursuit and there’s still something taboo about it. For the past 18 months I’ve been eating beef brisket instead of pasta and having coffee and eggs instead of crumpets for breakfast. I didn’t even lose a stone on Ozempic – now I’ve lost seven.

Dr Seyan says:‘Human bodies are highly complex, and weight-loss medications will not affect everyone in the same way. It’s important to note that in the UK, Ozempic is not currently approved for weight-loss purposes, though this varies across the globe.

‘A slower or limited response does not mean that the treatment has ‘failed’ or that the patient has done something wrong. There is wide variation in how people experience appetite suppression and metabolic change.

‘Underlying conditions such as PCOS can make weight loss more challenging due to insulin resistance and hormonal factors.

‘Some individuals experience less appetite suppression, ­meaning weight loss is slower, even when following medical guidance, and combining the medication with a balanced diet and exercise.

‘Patients unsure about their progress on weight-loss drugs should speak to their doctor, who can review their treatment, ­reassessing lifestyle factors, looking at the dose taken, or considering alternative medications where appropriate.’

‘It destroyed my relationship with food’

Suzanne Young, 51, is a project manager and executive coach. She lives with her husband in Northamptonshire.

Weight lost on jabs: 19lb (1st 5lb) before she put it all back on

Money spent: £3,329.89 (£175.26 per lb of weight lost)

I’ve always been overweight and struggled with emotional eating. The insults started when I was young.

I still remember the friend who asked me: ‘Do they do bikinis in your size?’ when I was an average size 14. People who are overweight are perfectly aware they are big, and yet others somehow always feel the need to remind you.

I’m a successful woman, I’m in charge of everything in my life, but my weight is something I’m simply unable to crack.

Five years ago, I decided to make a change. I resolved to follow a high-protein, unprocessed diet and take online exercise classes. I had quite a bit of success, dropping from over 16st to 14st (I’m 5 ft 4in).

But after a skiing accident and our move into a bungalow, the weight started to pile back on. I was at 15st 4lb: my clothes stopped fitting and I felt sluggish and miserable.

It was October 2023, Wegovy had just launched in the UK and was all over the news. A ‘quick fix’ appealed to me so, via Google, I signed up with a clinic, filled in a form and started jabbing myself with the starter dose of 0.25mg.

The drug cost £179 a month to start with, going up to almost £300 when I hit the maximum dose. I told myself I would try it for a year, and see how I went.

For the first month, I was definitely eating smaller portions, but the scales barely seemed to budge and after a few weeks I began to feel like a failure.

Plus, being on Wegovy further messed up my relationship with food. The last time I’d lost weight, I had eaten healthily, but eaten well. This time around, I was worried that I wouldn’t get enough nutrition from my smaller portions so I chose more calorific options: a chicken curry instead of a chicken salad.

At other times, I’d think ‘sod it – as I can’t eat much, I might as well treat myself’, so I’d have a bar of chocolate.

In November 2024, after a year on Wegovy, I decided to stop: I was going to wean myself off, but in the end, I went ‘cold turkey’.

Over time, my appetite came back, as did the comfort eating and the snacking.

By Christmas 2025, I was back up to 16st 2lb.

I’ve now returned to the high-protein, lower calorie diet, coupled with exercise, that worked for me before and it seems to be working again: I’ve already lost 4lb.

I understand totally why people turn to weight-loss drugs – there’s so much prejudice against big people that it can make you feel desperate – but to me, having the correct mindset around food is far more important.

Dr Seyan says: ‘Changes in appetite can be confusing when starting weight-loss drugs, and it’s common for people to gravitate towards foods that feel comforting or filling.

‘In some cases, this may mean choosing higher calorie or less nutritious options, despite a reduced appetite. It’s important to consciously make a mindful choice when it comes to meals.’