What is the best injection for weight loss?

Most of these injections are part of a group called GLP-1 receptor agonists, which mimic a hormone in your body that regulates your appetite and digestion.

These treatments are prescribed by a healthcare professional and work best when combined with a healthy diet and exercise. Some injections that are not licensed for weight loss, like lipotropic injections or B12 shots, aren’t clinically proven to be effective for weight loss.

Early medications worked by suppressing appetite or reducing fat absorption. However, appetite suppressants often led to psychological side effects, while fat-absorption blockers resulted in bowel-related issues.

Surgical procedures to remove peripheral fat can be effective for cosmetic purposes, but they come with surgical risks and do not improve overall health or cardiovascular health, which is associated with visceral fat.

Bariatric surgery, which results in more than just peripheral fat loss, is an evolving field, with advances making it safer, and offering some secondary health benefits. 

The discovery of GLP-1 receptor agonists marked a turning point. Originally developed to treat diabetes, these medications were found to have a significant effect on weight loss. The first GLP-1s were licensed for fat loss in the USA in 2014, since then hundreds of thousands of injections have been used worldwide. Today, treatments like Mounjaro and Wegovy have rapidly demonstrated a track record in effective weight loss. 

The best injection for weight loss varies depending on the individual, their health history, and what long term health conditions they may have. Below we have listed different injections, the brand name is listed first, with the drug name in brackets. This list is sorted by how much weight you could lose on each medication:

1. Mounjaro (Tirzepatide)

• Weight loss – Up to 26% weight loss
• How it works – A newer treatment that targets two different hormones for appetite and improved metabolism
• Benefits – Promising results in early studies, with even greater weight loss than Wegovy and Saxenda. Recently shown to be well tolerated over longer periods of time. 
• Common side effects – Nausea, diarrhoea, vomiting and stomach ache

2. Wegovy (Semaglutide)

• Weight loss – Up to 15% weight loss
• How it works – Wegovy helps you feel full sooner and reduces hunger, making it easier to eat less
• Benefits – Significant weight loss in clinical trials, often 15% of body weight
• Common side effects – Nausea, diarrhoea, vomiting, stomach ache, headache and feeling weak or tired

3. Saxenda (Liraglutide)

• Weight loss – Up to 10% weight loss
• How it works – Similar to Wegovy but taken daily instead of weekly
• Benefits – Effective for weight loss
• Common side effects – Nausea, diarrhoea, vomiting, constipation, headache, risk of thyroid tumours

Choosing the right injection depends on your personal health and lifestyle.

Factors to consider

• Your BMI and overall health
• Any medical conditions you may have
• Family history of medical conditions
• Whether you prefer daily or weekly treatments
• The cost of treatment (some are available through the NHS)

A doctor’s perspective

As a GP, I consider several factors before prescribing weight loss injections:

• Medical history – Is the medication appropriate for a patient with this medical and family history?
• Cause of obesity – Is there an underlying cause to be addressed first?
• Weight history – What has the patient previously tried to lose weight?
• Evidence – Has the proposed medication been clinically proven to work in similar patients?
• Tolerability – Is the patient likely to tolerate taking the medication (i.e. injections) and its side effects? 

The best option varies from person to person, so consulting a clinician is always the first step.

Benefits

• Proven weight loss, with up to 26% reduction in body weight.
• Improved health, including reduced risks of diabetes and heart disease.

Risks

• Side effects like nausea, diarrhoea, vomiting, stomach ache and constipation.
• Cost, especially for private treatments.
• Weight gain is common following stopping treatment.

• Oral medications – Easier to take but injections are typically more effective.  
• Surgery – Risks of surgery, and not all have the secondary health benefits such as reduced risk of heart attacks and diabetes. 
• Lifestyle-only approaches – Essential but unlikely to make significant changes in weight on their own.

Injections offer the effectiveness, convenience, and secondary health benefits.

Can I use weight loss injections without a prescription?

No, weight loss injections like Mounjaro, Wegovy and Saxenda require a prescription from a qualified clinician in the UK. These medications should only be used under the supervision of a healthcare professional. Your clinician will assess your medical history, BMI, and other factors to ensure the treatment is safe and appropriate for you. Self-medicating or obtaining these injections without proper guidance can lead to serious health risks, including dangerous side effects and improper dosing. If you obtain medication from anywhere other than a registered pharmacy, there is a high risk that the medication is not genuine, which at best could have no benefit, but at worst could have significant health implications. 

How long does it take to see results with weight loss injections?

Many patients begin to notice changes within 4 to 8 weeks of starting treatment. Initial results may include reduced appetite and minor weight loss. Significant weight loss, such as 26% of body weight, typically occurs when a patient has gradually increased the dose up to the maximum dose, and then uses the medication as prescribed, and combines it with a healthy diet and exercise routine. It’s important to stay patient and track progress over time, as weight loss isn’t always linear.

Are weight loss injections suitable for everyone?

No, weight loss injections aren’t suitable for everyone. They’re typically prescribed if you have a BMI of 30 or higher or if you have a BMI of 27 or higher and also have weight-related health conditions like type 2 diabetes or hypertension. Always consult a healthcare professional to assess if the medication is suitable for you.

What happens after stopping weight loss injections?

When you stop taking weight loss injections, there’s a high risk of regaining the weight. The injections help reset your body’s appetite and metabolism, but long-term success depends on continuing to eat a low calorie, balanced diet, staying physically active, managing stress and sleeping well. Some patients may transition to other treatments or programmes to support weight maintenance after stopping injections.

How do weight loss injections affect fertility?

Weight loss injections may improve fertility as people who are in a healthy weight range have an increased chance of successful conception. However, the medication itself is not designed to directly impact fertility. If you’re planning to conceive, discuss your treatment plan with your doctor to ensure safety, as these medications aren’t recommended if you are pregnant or breastfeeding.

How do weight loss injections impact blood sugar levels?

Mounjaro can lower blood sugar levels, especially in patients with type 2 diabetes. This is generally beneficial but may increase the risk of hypoglycemia if you’re taking other diabetes medications. Regular blood sugar monitoring is crucial, and your clinician may adjust your medication to reduce the risk of hypos.

Weight loss injections like Mounjaro, Wegovy and Saxenda can be beneficial if you’re struggling with weight management. The best injection depends on your unique needs and health goals.

Remember, no injection works alone – it’s about pairing treatment with healthy habits for long-term success.

Disclaimer

This article is for general information only and should not be used for the diagnosis or treatment of medical conditions. Medic Spot Limited has used all reasonable care in compiling the information but makes no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. In the event of an emergency, please call 999 for immediate assistance.

There is no guarantee of a specific weight loss medication being prescribed. Clinicians will review your online questionnaire and will recommend the most appropriate weight loss treatments for you based on your answers. In some cases the clinicians may contact you for additional information. See our Terms of Service for more information.