Weight Loss Injections UK: types, results, risks and who they’re for
If you’ve searched for “weight loss injections”, “the weight loss shot” or even “weight loss injection near me”, you’ve probably seen a mix of:
Evidence-based medicines like Wegovy (semaglutide) and Saxenda (liraglutide)
Newer weight loss jabs linked to diabetes drugs
Vague “slimming injections” that don’t clearly explain what’s in them
In the UK, when people talk about weight loss injections, they usually mean GLP-1 medications such as semaglutide (Wegovy) or liraglutide (Saxenda), and increasingly tirzepatide (Mounjaro) – all prescription-only medicines with clear clinical trial data behind them.
There are also non-evidence-based “fat-burning” or vitamin slimming jabs marketed privately. These are not the same as licensed GLP-1 weight loss injectable medication and often have limited or no robust data.
This guide walks you through:
What weight loss injections actually are
How these weight loss injectables work
Who might be eligible in the UK (NHS vs private)
Realistic results and timelines
Key risks, side-effects and red flags
At the end, we’ll explain how Piko’s doctors assess whether a weight loss medication injection is appropriate for you – with no “miracle cure” promises.
What are weight loss injections and how do they work?
When we talk about weight loss injections or weight loss jabs in the UK, we usually mean prescription medicines that you inject under the skin (subcutaneously), using a pre-filled pen.
The main group are GLP-1 receptor agonists – drugs that mimic a natural hormone called GLP-1.
The main evidence-based weight loss injectables in the UK
1. Semaglutide (Wegovy) – weekly weight loss injection
Licensed in the UK specifically for weight management.
Given as a once-weekly weight loss injection with gradually increasing dose.
Also available as Ozempic for diabetes (different licence; weight loss use is off-label).
2. Liraglutide (Saxenda) – daily weight loss injection
A daily weight loss injection used alongside diet and activity changes.
Comes as a pre-filled pen the patient injects once a day.
3. Tirzepatide (Mounjaro) – weekly dual-action injection
Originally licensed for type 2 diabetes and now being introduced as a weight management option in the UK.
Acts on two hormone receptors (GIP and GLP-1), which may lead to greater average weight loss in trials.
You may also come across orlistat (a capsule that blocks fat absorption) which is technically not an injection, but is sometimes mentioned alongside weight loss medicines.
How GLP-1 weight loss injection medicine works
GLP-1 and related drugs help weight loss by:
Reducing appetite and hunger
Acting on appetite centres in the brain so you feel fuller with less food
Slowing stomach emptying
Food stays in the stomach longer, which can make you feel fuller for longer
Improving blood sugar control
Helpful especially in people with insulin resistance or type 2 diabetes
In simple terms, these weight loss injectable medicines help you want to eat less and make it easier to stick to a reduced-calorie diet.
Even the “best weight loss injections” only work properly when combined with lifestyle changes – they are not a stand-alone fix.
You might see phrases like “new weight loss jab”, “new shot to lose weight” or “loss weight shot” in the media; they’re usually referring to these GLP-1 or GIP/GLP-1 medicines.
Who might be eligible in the UK?
Eligibility depends on:
Which medicine (Wegovy, Saxenda, Mounjaro, etc.)
Whether you are going through the NHS or a private provider
Your BMI and any related health conditions (comorbidities)
Always remember: these are prescription-only treatments. A doctor or prescribing clinician must assess whether they’re safe and appropriate for you.
Basic BMI concepts
BMI (Body Mass Index) = weight (kg) / height (m²)
Broad categories (for adults of white ethnicity):
25–29.9: Overweight
30–34.9: Obesity (Class I)
35–39.9: Obesity (Class II)
40+: Obesity (Class III)
Thresholds are lower for some ethnic groups (e.g. South Asian, Black, Chinese, Middle Eastern), because obesity-related risks start at a lower BMI.
NHS criteria for weight loss injections
NHS access is designed for people with higher health risks and often requires:
High BMI plus weight-related health problems, and
Referral into a specialist weight management service
For Wegovy (semaglutide), NICE guidance recommends it for adults with:
A BMI ≥ 35 kg/m² and at least one weight-related comorbidity (e.g. hypertension, cardiovascular disease, sleep apnoea),
orA BMI 30–34.9 kg/m² when they also meet criteria to be treated in a specialist weight management service.
Local NHS areas can implement additional restrictions (for example, BMI ≥ 40 with several comorbidities) because of limited funding and medicine supply.
For Saxenda and Mounjaro, NHS criteria are similarly strict: they’re generally reserved for people with severe obesity and multiple risk factors within specialist services.
Private eligibility criteria (typical)
Private clinics often follow the product licence and international obesity guidelines, which are usually broader than NHS rules. For GLP-1 weight loss injections, typical private criteria are along the lines of:
BMI ≥ 30 kg/m² (obesity), with or without comorbidities, or
BMI ≥ 27 kg/m² with at least one weight-related condition, such as:
High blood pressure
Type 2 diabetes or pre-diabetes
High cholesterol
Obstructive sleep apnoea
Some private services may have slightly different thresholds or may not prescribe if:
You’re pregnant, planning pregnancy or breastfeeding
You have certain endocrine disorders or a history of pancreatitis
You’re on interacting medication or have specific kidney/liver problems
If you’re googling “weight loss injections near me” or “weight loss injection near me”, the safest approach is to choose a regulated clinic that:
Uses licensed weight loss injectable medication, not unproven “slimming shots”
Provides doctor-led assessment
Offers ongoing monitoring and clear safety information
Realistic results & timelines
A key question people have about weight reduction injections is:
“How much weight can I actually expect to lose?”
The honest answer: it varies, and clinical trial averages are not promises. But they give a useful ballpark.
Semaglutide (Wegovy) – STEP trials
In the STEP 1 trial of semaglutide 2.4 mg once weekly in adults with obesity or overweight plus a comorbidity (diet & lifestyle support included):
Average weight loss at 68 weeks: ~15% of starting body weight
Many patients lost 10–15% or more
Some lost less; a minority did not respond well
Other analyses show similar results (~15% weight loss at around 2 years with continued treatment).
Liraglutide (Saxenda)
Trials of liraglutide 3 mg daily showed:
Average weight loss of ~5–8% of starting weight over about 1 year
More patients reaching ≥5% or ≥10% weight loss than placebo
Tirzepatide (Mounjaro)
For tirzepatide (mainly studied in diabetes and obesity trials):
Some studies show average weight loss above 20% at higher doses
It’s one reason it’s often described as a “new weight loss jab” or “the new shot to lose weight” in the media
Other medicines (e.g. orlistat)
Orlistat typically results in more modest weight loss (about 3–5% of starting weight) on average over a year, mainly through reducing fat absorption from food.
Timelines: how fast do weight loss injections work?
Typical pattern with GLP-1 weight loss medication injection:
First 4–12 weeks:
Dose is slowly increased
Many people notice reduced appetite and a few kilos of weight loss
3–6 months:
Weight loss tends to accelerate if lifestyle changes are in place
Many patients reach 5–10% loss in this window
6–12+ months:
Rate of loss often slows
Some patients reach 10–15%+ loss over a year or more
Studies also show that stopping these medicines often leads to partial weight regain if lifestyle and behavioural changes aren’t maintained.
A “new shot to lose weight” isn’t a one-off injection. These are long-term treatments that work best when paired with sleep, nutrition, movement and mindset changes.
Risks, side-effects and red flags
Any weight loss injectable medicine can have side-effects. Most are mild and manageable, but some can be serious.
This is why a doctor-led prescription and monitoring plan is essential – especially if you’re tempted by a cheap “daily or monthly weight loss injection” from a clinic that doesn’t explain the risks clearly.
Common side-effects (GLP-1 / GIP-GLP-1 injections)
Most people experience some degree of gastrointestinal symptoms, especially when doses increase:
Nausea or feeling sick
Vomiting
Diarrhoea
Constipation
Bloating, indigestion or reflux
Reduced appetite (expected, but sometimes too strong)
These are often dose-related and may improve with time and slower dose escalation.
Less common but important risks
Depending on the specific drug and your medical history, serious risks can include:
Pancreatitis (inflammation of the pancreas) – severe abdominal pain, often with vomiting
Gallbladder problems / gallstones
Worsening of existing kidney problems (usually in the context of dehydration from vomiting)
Possible increased risk of certain thyroid tumours in animal studies (leading to warnings for those with a personal/family history of medullary thyroid carcinoma or MEN2)
Interaction with other diabetes medications, potentially causing low blood sugar (hypoglycaemia)
Who might not be suitable?
Your doctor may avoid or be very cautious with weight loss injections if you:
Are pregnant, planning pregnancy or breastfeeding
Have a history of pancreatitis
Have severe gastrointestinal disease
Have certain endocrine tumours or MEN2
Have advanced kidney or liver disease
Have uncontrolled psychiatric illness or eating disorders
Red flags with “slimming jabs”
Some clinics (and even beauty salons) promote:
Vitamin B12 injections marketed as fat-burning
“Lipotropic” or “fat-dissolving” injections with unclear ingredients
Unlicensed “natural weight loss injections”
Problems to watch out for:
Vague or missing information about what drug is being injected
No clear doctor assessment or medical history taken
No explanation of side-effects, contraindications or what happens if you feel unwell
If something simply promises “the weight loss jab” or “the weight loss shot that melts fat naturally” without specifying the active medicine and licence, treat it as a major red flag.
Thinking about weight loss injections? How Piko helps
If you’re at the stage of googling things like:
“best weight loss injections UK”
“the weight loss jab my friend is on”
Or “weight loss injections near me”
…it’s easy to feel overwhelmed and unsure who to trust.
At Piko, we take a doctor-led, safety-first approach to weight management. Here’s how our digital weight loss programme works around injectable options:
1. Comprehensive digital assessment
You start with:
A detailed medical questionnaire (BMI, weight history, medications, conditions)
Lifestyle and psychological factors (sleep, stress, eating patterns)
Our clinicians use this to decide whether weight loss injectable medication might be appropriate, or whether other approaches are safer and more suitable.
2. Doctor appointment & eligibility check
You have an online appointment with a doctor who will:
Review your medical history and current medication
Check your BMI and obesity-related risks
Discuss pros and cons of options (including non-injectable routes)
Explain realistic expectations and timelines (no “guaranteed” results)
If you’re eligible and it’s clinically appropriate, they may prescribe a weight loss medication injection (such as a GLP-1), or recommend alternative strategies.
3. Ongoing monitoring – not just a jab
Weight loss injections work best when combined with:
Personalised nutrition guidance
Activity and movement you can sustain
Sleep, stress and habit support
Through the Piko app, you can track your weight loss over time, monitor symptoms, and keep an eye on side-effects so they can be addressed early.
4. No miracle claims
We’ll never tell you there’s one magic “loss weight shot” that works for everyone.
Instead, our promise is:
Transparent, evidence-based information
Honest discussion of risks and benefits
Doctor-supervised treatment if injections are right for you
Support to build habits that keep weight off long after any injection course ends
Key takeaways
In the UK, “weight loss injections” usually refer to GLP-1 or GIP/GLP-1 medicines like Wegovy, Saxenda and Mounjaro.
NHS access is limited to people with higher BMI and significant comorbidities in specialist services; private clinics can often treat at lower BMI thresholds, within licence.
Clinical trials show average weight loss of ~5–8% (liraglutide), ~15% (semaglutide) and potentially even more for tirzepatide – but individual responses vary.
Side-effects and risks mean that these medicines should only be used under medical supervision – be cautious with vague “slimming jabs” that don’t clearly explain the active drug.
Piko’s doctors assess your situation, explain options clearly, and only recommend weight loss injectables when they’re safe, indicated and combined with a structured lifestyle programme.
