Weight loss treatments have become one of the most talked-about solutions for weight management. These medically supervised medications are designed to help reduce appetite, improve blood sugar control and support significant weight loss. In this blog, I will explore all the major injections available today, those that were used in the past, and exciting new treatments currently in development. I will also cover how they work, expected results, benefits, risks and who should avoid them.
What Are Weight Loss Treatments, and How Do They Actually Work?
Weight loss treatments are often administered just under the skin, and target hormones that affect both how hungry you feel and how your body burns calories. Most of these treatments mimic or boost the action of hormones that are naturally present in the gut. Key hormones include Glucagon-Like Peptide-1 (GLP-1), Glucose-Dependent Insulinotropic Polypeptide (GIP), and Amylin. These hormones work together to regulate blood sugar, slow down digestion, and reduce feelings of hunger. The end result is to eat less and, as a result, lose weight.
Current Treatment Options
Semaglutide (Ozempic and Wegovy)
Semaglutide, a GLP-1 receptor agonist, was created by Novo Nordisk. This medication works by increasing insulin release, decreasing glucagon (a hormone that raises blood sugar), slowing down how quickly the stomach empties, and reducing appetite.
- Weight Loss: Clinical studies show an average weight loss of 15% over 68 weeks.
- Muscle Loss: About 40% of the weight lost might be lean muscle, which highlights the importance of exercise and getting enough protein.
- Administration: The drug is given as a weekly injection, injected into the abdomen, thigh, or upper arm. The dosage gradually increases.
- Side Effects: Possible side effects are nausea, vomiting, constipation, and gallstones. A rare but serious risk of pancreatitis exists. The long-term consequences are still under investigation. Those with a past history of medullary thyroid cancer, Multiple Endocrine Neoplasia type 2, or those who are pregnant should steer clear.
This is a prescription-only medicine and should only be used under medical supervision.
Tirzepatide (Mounjaro and Zepbound)
Eli Lilly developed Tirzepatide, which acts as a dual agonist for GLP-1 and GIP receptors, providing a more potent appetite-suppressing effect.
- Weight Loss: Clinical trials have shown a potential reduction of up to 22% in body weight.
- Muscle Loss: The risk is comparable to that of Semaglutide, unless accompanied by lifestyle modifications.
- Administration: A weekly injection is required as above, with doses gradually increased.
- Side Effects: Gastrointestinal disturbances are common, and there are rare instances of pancreatitis and gallbladder problems.
This is a prescription-only medicine and should only be used under medical supervision.
Emerging Treatments
Retatrutide
This triple agonist, a creation of Eli Lilly, targets GLP-1, GIP, and glucagon receptors.
- Projected Weight Loss: Anticipated weight loss could reach 29%, a figure on par with outcomes from bariatric surgery.
- Side Effects: There have been reports of nausea, diarrhoea, and tingling.
CagriSema
Novo Nordisk is developing a therapy that combines semaglutide with cagrilintide, an amylin analogue.
- Projected Weight Loss: Roughly 20–23% after 68 weeks.
- Advantages: This combination therapy is designed to boost success rates for individuals who haven’t seen results with GLP-1 treatments on their own.
Amycretin
Novo Nordisk is working on Amycretin, a novel therapy that tries to mimic both GLP-1 and amylin.
- Projected Weight Loss: Initial research suggests a 22–24% decrease in weight over a 36-week period.
- Considerations: Higher doses have been associated with an increase in gastrointestinal side effects.
MET-233i
Metsera (Pfizer) is developing MET-233i, a long-acting amylin analogue.
- Projected Weight Loss: Early data indicates up to 8% weight loss within just 5 weeks.
- Distinct Advantage: Monthly dosing could offer a more user-friendly approach.
Eloralintide
Eli Lilly is working on an amylin receptor agonist.
- Expected Weight Loss: Up to 20% in 48 weeks.
- Possible application: This could be a significant advancement for individuals who haven’t had success with GLP-1 treatments.
Oral Wegovy
Novo Nordisk, the company behind the original injectable, has introduced an oral version of Wegovy, and it has received FDA approval.
- Oral formulation produces weight loss comparable to the injectable GLP-1 Wegovy. Patients in clinical trials experienced an average weight loss of 16.6%, with roughly one-third shedding 20% or more of their body weight.
- Similar side-effects to the injectable treatment such as nausea, vomiting and diarrhoea.
- Tablets are a taken daily, whereas the injectables are administered weekly. Taking the tablet requires an empty stomach with a sip of water. After taking the tablet, patients should refrain from eating, drinking, or taking any other medications for half an hour.
- Tablets are a cost-effective option compared to weight loss injections. The tablets are likely to be available in the UK by the summer of 2026.
Potential Benefits
- Significant weight loss is achievable, and it doesn’t involve surgery.
- Improved blood sugar control and a reduced risk of type 2 diabetes are potential outcomes.
- There may also be benefits for heart health.
Potential Side Effects
Common side effects include nausea, vomiting, diarrhoea, and constipation. Though less common, more serious complications can occur, such as pancreatitis, gallstones, and potential thyroid problems. We’re still gathering information on the long-term safety of these injections.
Important Safety Information
Unsupervised use of these drugs can lead to harm with loss of the “wrong type of weight” with consequences especially when coming off these drugs after the desired weight loss. To understand this, one has to understand the normal physiological composition of the body and how it is affected by these weight loss treatments. You can read more about this here.
Stopping these injections can cause rebound increase in appetite and significant weight gain and this gain is largely due to the deposition of fat rather than the reaccumulation of muscle loss. This is very undesirable as the overall loss in muscle mass (if not minimised with lifestyle changes and better exercise regime) will result in reduced metabolic activity and a reduced ability to burn the excess calories after stopping the injections. It is therefore, very desirable to ensure that these slimming injections are taken under medical supervision and especially so when planning to wean yourself off them.
Because these drugs work partly by delaying gastric emptying, it is very important that the use of these drugs is disclosed to the medical team if you are planning to have any surgery that will involve a general anaesthetic. Prior to any general anaesthetic, patients are usually asked to have starved for 6 hours to ensure that the stomach is empty. Presence of any food in the stomach during anaesthesia poses a significant risk as this can inadvertently reflux back and enter the airways to the lungs where it can have very serious consequences. Patients on these drugs may still have undigested food in the stomach after 6 hours and hence the advice you need to follow prior to any surgery may need to change.
Who Should Avoid These Treatments?
Pregnant or breastfeeding women are advised against them. Furthermore, those with a history of certain thyroid cancers, along with those suffering from severe gastrointestinal problems, should also steer clear.
Summary
Current weight loss treatments, such as Semaglutide and Tirzepatide, generally lead to a 15–22% weight loss within a year to a year and a half. Future treatments could potentially push that figure to 29%. But, to keep muscle mass intact, resistance training and a good protein intake are essential.
These treatments are a significant advance in treating obesity. These medications aren’t a cure-all; they work best when combined with a healthy diet, regular exercise, and medical oversight.
Back to Articles