Losing weight effectively and safely - your questions answered about new weight loss pills and injections

Your questions answered on how best to lose weight when considering new weight loss medicines and taking a whole-person approach to health.

What are the new weight loss medicines?

Tirzepatide (brand name Mounjaro) and Semaglutide (brand name Wegovy) are protein like molecules that are naturally secreted by our guts in response to food (GLP 1 analogues). These have been artificially synthesized to last longer in the body. Scientists believe that they work by slowing the movement of food through our gut, which makes us feel fuller for longer, but on the flip-side can result in constipation, nausea and vomiting. They also make us produce more insulin hormone which lowers the blood sugar after meals, and they work on the areas of the brain that drive hunger to quieten down what many refer to as “food noise”.  As a result, we eat less, may choose healthier options and lose weight.

Mounjaro has two types of artificially synthesized protein like molecules so has a dual effect and therefore more powerful appetite suppressing impact.

You can book to discuss these options with Dr Fallows here.

How much weight can I expect to lose on semaglutide/tirzepatide?

Everyone is different and not everyone loses weight with these medicines. However, these are the first medicines that really have shown impressive weight loss in medical trials that range from 15-25% of your starting weight. For some people, this amount of weight loss won’t always achieve a healthy body mass index, but it does still improve our health. This is because excess weight drives high blood pressure, joint pain from osteoarthritis, type-2 diabetes and many other health conditions including depression.

We will make a complete holistic health review that assesses all of the drivers of weight gain – not just food and exercise – for many people weight gain has been driven by many factors. These factors can also include poor sleep, shift work, stress, low mood, other prescribed medicines or other health conditions like thyroid issues or menopause. In practice, for some people, simply addressing sleep and stress issues can be the most powerful way to lose weight and don’t need a weight loss prescription.

We can also prescribe HRT which can help improve sleep, reduce stress and shift weight from unhealthy areas such as around the tummy to the hips and breasts.  We will review the other medicines you might be taking to ensure these are not contributing to weight gain – for example antidepressants, blood pressure and contraceptive medicines. I can prescribe medications for many long term conditions – importantly, I can also support you to wean off medications you might no longer need or feel you no longer want to take.

We will be able to address all these issues to ensure you get the most out of your weight loss appointment.

I’ve got a wedding coming up and need to lose weight fast! Will these work for me?

Whilst it’s tempting to try to lose weight fast, particularly for events like weddings or if you’re waiting to get a knee replacement, don’t rush this!

Very rapid weight loss (more than 1kg/week) may not always be the best option for you as it can increase the chances of problems with the gall bladder, for example gall stone formation, blockage, infection and bursting of the gall bladder or even pancreatitis which can be very serious. We will assess your risks of problems with the gall bladder and arrange liver ultrasound scans if these are needed.  

“very rapid weight loss can have health risks – speak to an expert to get personalised support”

The speed of weight loss depends on the dose of the medicine and how they affect you as well as how much support or effort you are able to make with other factors such as reducing stress, improving sleep, keeping active and changing to healthy, whole foods.

Whilst short term (24hrs to 3 days), intermittent, supported fasting can be safe for some people and lead to improved health, severely restricting what you eat or having very suppressed appetite can cause problems. For example, if you already have some vitamin or mineral deficiencies or are on particular medications, this can be very risky. In the US, there are reports of serious nutritional deficiencies causing permanent brain damage (a syndrome called Wernicke’s encephalopathy) in a few people who had severely suppressed appetite on new weight loss medicines. We will assess your nutritional status (whether you are at risk of any deficiencies already), ensure these are addressed or tested for if needed, then we will develop a personalised nutrition plan depending on your own food preferences.

Are weight loss medicines safe?

No medicine is 100% safe. Whilst there are health risks with continuing to carry excess weight these need to be balanced with the chances of risks with these new medicines. This is where speaking to an expert clinician can help – not only do we know the trial data, we also have experience supporting people using these medicines and can personally assess and discuss your own situation.

Researchers find out about harms of medicines from medical trials, but these aren’t the same as real life use of medicines and sometimes underestimate risks. We are still collecting data from Mounjaro's use in real-life (non-research settings) so this information may change with time to show the medicine is more or less safe than we thought. Again, keeping your medication under review by a clinician is a good idea – this way you can be updated with any changes in this research.

People with Type-2 diabetes have been using Semaglutide since 2017 and it is considered to be safe. Safe means that the risks of serious harm from things like pancreatitis and gall stones for example are thought to be much less than the benefits of losing excess weight.  

Semaglutide has been found to lead to weight loss that also reduces the chances of heart attack and stroke, metabolic liver disease (fat in the liver), and other health problems associated with high weight. This is important – don’t forget there are unhealthy ways to lose weight! For example, we lose weight with starvation, some eating disorders, alcoholism, heroin addiction and cancer – clearly none of these helps us to feel good or live longer. How we lose weight therefore matters a lot; this is where seeing an expert who can personally assess your whole health, can ensure you get the best outcomes from any prescription.

“How we lose weight matters – there are plenty of ways we can lose weight but don’t end up feeling better or living longer!”

What are the common side‑effects of GLP‑1 medicines?

The most common side effects are nausea, vomiting, diarrhoea or constipation. These depend on the dose, often all we need to do is reduce the dose and increase more slowly. These side effects may also be reduced with the right support around your nutrition. We are also able to prescribe other medications you might need in case of side effects but the aim is for fewer medicines overall.

Other side effects include hair loss related to rapid drops in weight – this usually re-grows and we can offer assessment and support for hair loss issues.

If you have surgery whilst you are on these medicines, you will need to discuss carefully with your anaesthetist as they slow stomach emptying and can lead to stomach contents ending up in the lungs during anaesthesia. We can help to optimize your health prior to any surgery – weight loss reduces risks of anaesthesia and may mean you could have day case surgery.

It’s important to remember that some people who previously considered themselves infertile, find that their fertility returns as they lose weight. We can review your contraceptive needs to ensure you don’t fall pregnant whilst on these medicines.

Who can’t take weight loss medicines?

If your BMI is in the normal healthy weight range, you shouldn’t and can’t use these medicines – if you want to get into better shape, there are much safer options we can help you with.

If you’re planning to get pregnant or are breast feeding you shouldn’t take Mounjaro or Semaglutide.

If you’ve previously had an eating disorder, it is important to discuss this in detail and whether this may be improved or worsened with weight loss medicines.

If you’ve previously had pancreatitis or some types of cancers, you shouldn’t use these medicines. People with gall stone problems, ideally should have these treated or lose weight gradually to prevent these worsening or creating serious problems.

If you’ve any condition that affects your ability to absorb nutrients from your food, this needs to be considered prior to any weight loss medicine. For example, coeliac disease, ulcerative colitis, Crohns or other malabsorption/ gut issues. In these instances, careful assessment and monitoring is needed. We can refer you to a dietician if needed for additional on-going support on top of our follow-up.

We will carefully screen you for any risks associated with these medicines and if possible, reduce these risks for example with gall stone type problems.

Will I need to take GLP-1 medicines long-term?

Research from real-world settings (use outside of medical trials) suggest that much of the weight is regained within 2 years of stopping these medicines and unfortunately, it looks like the weight is regained faster than if you lost the weight with a lifestyle intervention.

“Personalised, whole person assessment of the causes of your weight gain is important to help keep the weight off in the long term”

This is why personalised whole person assessment of the driving factors behind why you gained weight can be important – addressing these root causes mean you can reduce the chance of side effects, failure to lose weight and will be more likely to keep the weight off and achieve better health with it.

Can I get Wegovy or Mounjaro on the NHS?

It is currently very difficult to get weight loss medicines on the NHS. Even if you are prescribed these medicines, the support for lifestyle change is often less than ideal. We are happy to support you if you are receiving a prescription on the NHS, to ensure that you are addressing all your nutrition and lifestyle needs.

Until June 2026 only people with a BMI over 40 and 4 other complications from obesity are eligible for Mounjaro in some areas of the UK – this is very variable and depends on decisions and funding in different areas. After this date the BMI threshold drops to 35 but then in March 2027 it rises again to over 40 with only 3 complications (for example sleep apnoea, high blood pressure etc).

NHS specialist weight management services are prescribing Wegovy for people with a BMI over 35 but again this varies by area.

There can also be shortages of these weight loss medicines and funding for treatment with Mounjaro is only for 2 years currently. This is changing all the time as new research and funding is discussed.

How much do Wegovy and Mounjaro Prescriptions Cost?

Wegovy and Mounjaro cost about £200-300/month depending on which pharmacy you are using.

Both medicines are available in a per-loaded injection pen. The needles are tiny and often people say they barely feel the injection. We will support you in how to use these pens and tailor your doses according to your progress and any side effects.

Semaglutide (wegovy) may soon be available in pill form.

What should I eat whilst taking weight loss medicines?

Whilst your appetite is reduced, it is very important to get support to improve the quality of your diet – this means eating more whole foods and increasing amount of fruit and vegetables. When and how you eat also matter. At Walton Wellness, we will investigate all these aspects with you.

Many people worry about protein, whilst this is important to help maintain muscle mass, most people are getting enough protein but need to increase the amount of fibre from different fruits and vegetables.

“There is currently an over focus on protein when often we are getting sufficient quantity but need to pay more attention the quality of the foods we are getting it from. Most of us need more fibre and whole foods in our diet”

What sort of health improvements might I see, other than weight loss?

Some people lose enough weight to reverse or put into remission, long term conditions such as Type-2 diabetes, high blood pressure, metabolic liver disease (fatty liver), osteoarthritis and mental health issues. In practice, some clinicians are seeing people improve conditions such as heart failure, irregular heart rhythms (atrial fibrillation) and leg ulcers but this hasn’t been seen in medical trials yet. Reversing these conditions means you may need to reduce or stop other medicines that were originally prescribed. We can support you with this and communicate with your NHS GP where needed.

Even if you’ve managed to put some conditions into remission, you should keep going to your NHS annual review check-ups. This is particularly important once you’ve stopped weight loss medication or haven’t managed to keep the weight off and sustained lifestyle changes.

What other options do I have for weight loss?

We can support you with intensive lifestyle interventions to support weight loss. Whilst this is often slower, it is usually more sustainable and carries almost no risks. A personalised assessment of issues such as poor sleep, shift work, disrupted eating patterns, alcohol, smoking, vaping, excess caffeine, inactivity, stress, low mood etc. can help us to work out where you need the most support. We can also support you with medically tailored nutrition interventions such as fasting mimicking diets – where you eat a very carefully designed 5-day diet that triggers fasting pathways. This has been found to give you the benefits of fasting whilst still being able to eat – this avoids some of the risks of fasting and has been shown to improve biological ageing markers.

“We can offer medically supervised fasting-mimicking diets which have been found to improve biological ageing markers”

There are other medicines such as Orlistat (Alli) which is available over the counter. However, this is not a very effective medicine, it has unpleasant side effects and doesn’t result in improved health which is a key difference with the newer weight loss medicines. We don’t usually recommend this medicine.

We can refer you to private bariatric surgeons if you would like to consider this option – we can have initial conversations with you about this option. As with any operation, bariatric surgery carries risks and can have lifelong implications on how your digestive tract deals with food. However, even compared to weight loss medicines, it remains the most sustainable and impactful weight loss option.

Do you offer “wrap-around care” for weight loss medicines?

Yes, rather than having to see multiple different clinicians, the advantage of expert generalist GPs is that they have training in general medicine, psychiatry, metabolic health, preventive care and more. Uniquely as an experienced GP with obesity medicine, nutrition and lifestyle medicine qualifications I have experience supporting people with metabolic conditions, mental health and menopause issues.