Weight Loss Injections: Your Questions Answered
About weight loss injections
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To qualify for weight loss medication, you typically need to meet certain BMI requirements. This usually means:
BMI over 30, or
BMI between 27 and 30 with a weight-related condition or risk factor.
You must also be 18 or older. Each medication has its own specific guidelines, so a qualified prescriber will review your medical history and current medications to ensure it’s safe for you.
To check your eligibility, please complete our assessment form.
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Weight loss injections help control hunger by mimicking natural hormones in your body. GLP-1 (found in Wegovy® and Mounjaro®) and GIP (found in Mounjaro®) send signals to your brain that make you feel full, even after eating less. They also slow down digestion, so you stay satisfied for longer.
Many people struggle to cut calories or reduce snacking because they still feel hungry. By curbing appetite, weight loss injections make it easier to stick to a healthy diet and lose weight.
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Capsules like Orlistat/Xenical help you lose weight by preventing your body from absorbing some of the fat in your food. This means you take in fewer calories from fat, which can support weight loss over time.
Injectable treatments like Wegovy® and Mounjaro® work differently—they help control your appetite. These treatments mimic a natural hormone (GLP-1) that tells your brain you're full, helping you eat less. They also help regulate blood sugar and keep you feeling satisfied for longer.
Both types of treatments work best when combined with a healthy diet and regular exercise as part of your weight loss plan.
Your weight loss journey has the best chance of long-term success when you find a treatment plan and sustainable lifestyle that works for you as an individual. -
Injectable GLP-1 treatments can be up to six times more effective than diet and exercise alone and nearly twice as effective as weight loss tablets.
Mounjaro® is the most powerful option, as it combines GIP + GLP-1 for better results. Studies show that with the highest dose and healthy lifestyle changes, users lose an average of 20.9% of their body weight in 36 weeks and up to 25.3% in 88 weeks.
In comparison, Wegovy® users report an average weight loss of up to 15% after a year.
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GLP-1s (glucagon-like peptide-1 receptor agonists) are some of the most effective weight loss medications available.
They work by mimicking a natural hormone in your body that controls appetite, slows digestion, and helps you feel full longer. This makes it easier to eat smaller portions and reduce calorie intake, leading to gradual weight loss.
GLP-1s are the key ingredient in injectable treatments like Mounjaro® and Wegovy®, which work best when combined with a healthy diet and regular exercise.
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Yes, the injectable treatments (Mounjaro® KwikPen and Wegovy®), and Alli® are all licensed for weight loss in the UK.
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Mounjaro® is available on the NHS, but the eligibility for this in England is currently limited to:
People with a BMI of 40 or over, AND who have at least four of the below health issues:
High blood pressure
High cholesterol or fat levels in your blood
Sleep apnoea (trouble breathing while sleeping)
Heart disease
Type 2 diabetes
The eligibility criteria for accessing Mounjaro® via the NHS is different in Scotland and Wales. Patients in Northern Ireland currently do not have access to Mounjaro® through the public health and social care (HSC) system.
If you want to use injections as part of your weight loss journey, but are not eligible for this medication on the NHS, you can take a free short assessment to find out if a private prescription from PillTime is a suitable weight loss treatment for you.
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ou can get weight loss injections with a prescription from:
• Online pharmacy services, like PillTime Weight Loss
• Private doctors
• The NHS, but only through a specialist weight management service (not a GP)
Using weight loss injections
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You may notice a reduced appetite after just a few injections, but significant weight loss usually takes a few months. The full effects are seen once you reach the maintenance dose.
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The amount of weight you lose depends on the injection you take and how well you follow a healthy diet and exercise plan. Most people lose at least 5% of their body weight.
Wegovy® (2.4 mg maintenance dose) → Up to 15% weight loss after 68 weeks
Mounjaro® (15 mg highest dose) → Up to 22.5% weight loss after 72 weeks
You’ll see the best results once you reach the maintenance dose.
Find out more about how to manage weight loss when using weight loss pens.
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Mounjaro® and Wegovy® are once-a-week injectable pens that are simple to use.
They come pre-measured, so there’s no need for syringes or manual dosing. You can inject them into your arm, leg, or abdomen using a small, fine needle designed for a nearly painless experience.
Each pen includes clear instructions, and video demonstrations are available to guide you through the process.
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Yes! The NHS recommends at least 2.5 hours of exercise per week. Regular activity helps improve your results and supports a healthy lifestyle to keep the weight off long-term.
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Yes, but it’s best to limit or avoid alcohol because it can:
Add extra calories that make weight loss harder.
Increase side effects like nausea, vomiting, or stomach upset.
Lead to unhealthy food choices, making it harder to stick to your plan.
If you choose to drink, wait until you know how the medication affects you, especially when starting or increasing your dose.
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Yes! Wegovy®, Mounjaro®, and Saxenda® come in easy-to-use injectable pens with pre-measured doses, so you don’t need to handle needles. We will include guidance on how you use them, and the patient information leaflet includes clear instructions.
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When you stop using weight loss injections, the effects gradually wear off. How quickly this happens depends on how long you’ve been taking the medication and your dosage. It can take anywhere from a few days to a few weeks for your hunger levels to return to normal.
To maintain your weight loss, it’s important to stick to a healthy diet and exercise routine. If you stop too soon, there’s a chance you could regain the weight you lost.
These injections are designed for long-term weight management, as obesity is considered a chronic condition. They are generally safe to use long-term, as long as you don’t experience serious side effects.
Find out more with our guide to life after weight loss injections.
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It depends. If you stick to a healthy diet and exercise, you’re less likely to regain weight. However, if you return to old eating habits, you might gain some or all of the weight back.
Stopping treatment too early can also lead to weight regain. Follow your prescriber’s guidance on how long to continue the injections.
Find out more in our guide to maintaining weight after using weight loss injections.
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When taking weight loss tablets or injections, you may experience some side effects, which can vary depending on the treatment.
Common Side Effects:
Stomach issues – abdominal pain, diarrhea, or constipation
Nausea or vomiting – feeling sick or being sick
Headaches
Changes in taste
Fatigue – feeling more tired than usual
Losing weight quickly can also affect your body. You might notice loose or sagging skin where you've lost weight, or stretch marks as your skin adjusts.
For women, weight loss can also affect periods. Being overweight can cause irregular or missed periods, but during weight loss, your cycle may change again. Once you reach a stable weight, your periods may become more regular.
FAQs about weight loss injections for men
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The opposite is often the case. Emerging research suggests that anti-obesity medications including GLP-1 agents, like those in weight loss injections, may increase testosterone levels in some men with obesity or type 2 diabetes. It should be noted that this is still early research, and individual monitoring remains important.
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There is not currently any evidence of weight loss injection side effects that are specific to men and don’t affect women taking the same medication. The common side effects (nausea, gastrointestinal symptoms, risk of pancreatitis) can be experienced by anyone taking weight loss injections. Most side effects usually go away once the body adjusts to the medication and dose.
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Generally, men aged 18+ with obesity (BMI criteria as per NHS/privately) and weight-related health conditions may be eligible for a prescription. However, not everyone is suitable for taking weight loss injections and a full assessment must always be carried out by a qualified UK prescriber before you start taking this medication.
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Clinical trials indicate that men taking Mounjaro® can lose somewhere between 5%-20% of their body weight, over a period of up to 18 months. It’s important to note that everyone responds uniquely to medication and actual results depend on adherence, starting weight, fitness, muscle mass, metabolic health and lifestyle.
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It’s essential for men taking weight loss injections to use them in combination lifestyle changes, such as high levels of activity and a balanced diet. Maintaining these healthy habits will help to sustain the weight loss achieved and not regain it if you stop taking the medication.
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Rapid weight loss can affect both fat and muscle. Men using Mounjaro® or Wegovy® may notice changes in strength or exercise performance, especially if appetite has reduced significantly.
To protect muscle during weight loss treatment:
Eat enough protein throughout the day
Lift weights or use resistance training to maintain strength
Talk to your trainer (if you have one) about adjusting your routine
Give your body time to recover between sessions
Avoid skipping meals
Most men find that as body weight drops, body composition improves even if absolute strength changes slightly.
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It can be more challenging! This is often due to changes in metabolism, stress, lifestyle and hormone levels. Weight loss injections, combined with activity and a balanced diet, can help support progress at any age.
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Many men with obstructive sleep apnoea carry extra fat around the neck and abdomen, which can make the airway narrower and breathing harder at night. As weight comes down - especially visceral fat - the pressure on the airway often reduces too. This is why some men may notice they snore less, wake up fewer times and feel more awake during the day once they’ve been on Wegovy® or Mounjaro® for a while.
It’s not a guaranteed fix for everyone, and it doesn’t replace your usual sleep apnoea treatment, like CPAP (so it’s important to keep using them). But losing weight can make a real difference to how well you sleep and how refreshed you feel. If you have sleep apnoea, always consult with your GP or sleep specialist as you go, so they can guide you safely as things hopefully improve.
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There’s no evidence that Wegovy® or Mounjaro® harm male fertility. In fact, for some men, improving overall health and reducing excess weight can have a positive impact on things like testosterone levels, energy and general wellbeing, which all play a role in reproductive health.
If you’re having fertility checks or you and your partner are trying to conceive, it’s worth mentioning this to your prescriber so they can give advice based on your individual health and any other medications you’re taking. But for most men, these injections don’t cause fertility problems and may even support better hormonal balance over time.
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If you are training or aiming in your gym activity to build or maintain muscle, there are some important considerations if you’re thinking of starting weight loss injections.
Appetite may reduce, so ensure your diet includes enough protein to preserve muscle.
Because you lose fat mass, your body weight may reduce and possibly strength/performance in absolute terms will adjust. Body composition should improve.
Monitor your fatigue after workouts or training sessions to ensure recovery and speak to your trainer about adjusting load and nutrition.