Weight loss injections – all you need to know

Why injections for weight loss are an important option

Around the world, more and more people are becoming overweight, obese or seriously obese. And it’s having a dramatic effect on our mental and physical health.

In the US, obesity has become a serious health problem, with 4 in 10 adults now classed as obese – meaning they have a body mass index (BMI) of 30 or more. In the UK, it’s estimated that 1 in 4 adults are obese.

“Obesity is a risk factor for other health problems, such as high blood pressure and type 2 diabetes, which can raise your risk of a heart attack or stroke,” says Dr Ann Nainan, family doctor and Healthily expert.

“Getting to a healthy weight isn’t just about vanity, or fitting into a smaller pair of jeans. So new advances in weight loss medication, such as injections, could be a health intervention that many people can benefit from.

“However, it’s important to note that weight loss injections are recommended alongside diet and exercise changes – they’re not a standalone treatment.”

Why women in particular could benefit

According to figures from the Centers for Disease Control and Prevention (CDC) for 2013-2016, nearly half of US adults said they’d tried to lose weight in the past 12 months.

But a higher percentage of women had tried to lose weight (56.4%) than men (41.7%). And as more US women have severe obesity (11.5%) than men (6.9%), weight loss injections could be a valuable option for some women.

What injections are licensed for weight management?

There are currently 2 injectable medications licensed for weight management by the US Food and Drug Administration (FDA): semaglutide (Wegovy) and liraglutide (Saxenda). They’re also approved for weight management in the UK.

A third injection, tirzepatide, is expected to be licensed for weight loss in the US in 2023. It’s already available as an injection for type 2 diabetes, under the brand name Mounjaro, and has proved so popular that there have been shortages.

How well do they work?

Licensed/approved weight loss injections:

• have been through clinical trials for safety and effectiveness, and have been described as “gamechangers”
• work by reducing your appetite, and may reduce your body weight by up to 20%
• have been proven to help achieve significant weight loss in people with high BMIs and associated health problems
• don’t replace diet and exercise – they should be prescribed in combination with a healthy diet and increased physical activity
• may be used for a set period of time – your doctor will discuss next steps with you for maintaining a healthy weight when the injections are stopped

Do you regain weight when you stop them?

This can vary according to the type of injection, so you should ask your doctor about what the specific research says for your medication.

But 1 study of semaglutide (Wegovy) found that participants regained two thirds of the weight they’d lost a year after their weekly injections stopped.

“We’re still learning about how to get the best from weight loss injections, and why people regain weight when they stop,” says Dr Ann. “But the drugs are appetite suppressants, so what seems to happen is that when you stop taking them, your appetite returns and you eat more.

“But weight management to help you stay at your healthy weight is a key part of keeping your health and wellbeing on track.” Read about weight management.

Could weight loss injections be right for you?

If you’re struggling with your weight and it’s affecting your physical and mental health, your doctor may suggest weight loss medication to help you.

“If healthy eating and exercise aren’t working, talk to your doctor to see if you might benefit from weight loss injections they can prescribe,” says Dr Ann. “They’ll help you consider the pros and cons, and may discuss other options – such as weight loss pills or surgery – so you can work out a plan together.”

It’s a good idea to:

• tell your doctor about any health problems associated with your weight
• explain how you’ve tried to lose weight in the past, what’s worked and what hasn’t, and if you regained the weight
• acknowledge that you’ll also have to make diet and exercise changes in combination with having the injections

Weight loss injections might be suitable for you if the following criteria apply:

You have a high body mass index (BMI)

“Most weight loss drugs are recommended for use in people with a BMI of 30 or more,” says Dr Ann. “Or, if you have a BMI of 27 or more and also have weight-related health problems such as high blood pressure, type 2 diabetes or raised cholesterol.”

Read about how to work out your BMI.

Your doctor says you meet the health criteria

You have to fulfill certain criteria for your doctor to be able to prescribe weight loss injections. And they’re designed to be used in combination with diet and exercise measures.

You can afford them – or get them through your insurance

In the US:

• only a minority of private health insurers cover weight-management drugs for obesity alone: a 2018 study found only 11% offered some coverage. So check the terms of your policy
• medicines for obesity aren’t covered by Medicare
• costs vary, but they can be up to $1,500 a month – although discounts may be available under manufacturer schemes
• there’s currently no limit for how long you can take them – so in theory, you can take them indefinitely, which could be very costly

In the UK:

• they’re only prescribed on the NHS if you meet strict criteria, as part of a specialist NHS weight management service
• you need to have a BMI of 35 or more and at least 1 weight-related health problem (in exceptional cases, they may be available if you have a BMI of 30-34)
• they’re usually prescribed for a set time frame, and may be stopped if you don’t achieve 5% weight loss in 6 months

They work for you within a set time frame

“If the injections are working for you and the benefits outweigh any side effects, then you may want to continue with the drug long term – if it’s available and your doctor is happy with this plan” says Dr Ann.

“But if the drug doesn’t work for you within a specified period, it might not be worth you continuing to take it – particularly if you have side effects.”

Who can’t have weight loss injections

Weight loss injections aren’t suitable for you if:

• you’re pregnant
• you or anyone in your family has had a rare type of thyroid cancer called medullary thyroid carcinoma, or you have a rare condition called multiple endocrine neoplasia type 2 (MEN2). This is because some studies in rats found the injections increase the risk of thyroid cancer – though no cause and effect has been proved in humans
• you have a history of pancreatitis

What does it feel like to have weight loss injections?

The weight loss achieved with injections can be impressive, and trial participants mention their lack of hunger and the fact they’re not constantly thinking about food. Because the injections were originally developed as diabetes drugs, they also regulate blood sugar.

Here’s what a few people say about weight loss injections:

• Jen, who took part in a trial for Wegovy and lost more than 60lbs (27kg) – 22% of her body weight – says the drug completely changed her attitude to food. “I felt full after eating less, and I could decide not to eat if faced with food, as I didn’t feel hungry.” She says she didn’t have to think about calorie restriction during the trial, as she didn’t feel hungry. Unfortunately, however, she regained much of the weight after the trial ended, and now feels she is back to “a constant battle with food”
• in January 2023, comedian Rosie O’Donnell said she’d lost 10lbs over Christmas by taking tirzepatide and drinking less soda. She added that her appetite had significantly decreased and she spent less time thinking about food
• Twitter and Tesla head Elon Musk has been reported as saying his weight loss was due to “fasting and Wegovy”

Weight loss injections explained

Wegovy (semaglutide)

• What is it?
  Wegovy is the brand name for a 2.4mg semaglutide injection that’s licensed/approved for weight management in the US and UK. (Another injectable weight loss drug, Ozempic, isn’t licensed for weight management, although some people are using it.)

• How does Wegovy work?
  Originally developed as a diabetes drug, semaglutide is a ‘GLP-1 receptor agonist’. It works by hijacking your body’s appetite regulation system – so you have less appetite and therefore eat less.

• How do you take it?
  As a weekly dose that you inject yourself under your skin. The manufacturers say it should be used in combination with a reduced-calorie meal plan and increased physical activity.

• Does it get good results?
  Trials have reported weight loss of more than 20% of starting body weight. In a large, high-quality international study published in the New England Journal of Medicine, researchers found a third of people who took semaglutide for 68 weeks alongside diet and exercise changes lost at least 20% of their body weight, while more than two thirds lost at least 10%. The average participant lost about 33lbs (15kg).

• Any side effects?
  Common side effects of Wegovy include nausea, diarrhea, vomiting, constipation, tiredness (fatigue), belly (stomach) pain, upset stomach, bloating, stomach flu (gastroenteritis) and heartburn. A study that looked at digestive side effects found that 98 out of 100 people who had them said they were mild to moderate, short-lived and most common as the dose was increased. Nausea was the most common side effect, with 43 out of 100 people getting it (meaning 57 out of 100 didn’t). Rare side effects include gallbladder disorders – these were reported in 3 out of 100 of people in the New England Journal of Medicine trial. About 3 out of 1,171 people also developed mild acute pancreatitis (they all recovered during the trial period).

Watch this UK news report on semaglutide from March 2023.

Ozempic (semaglutide)

• What is it?
  You might have heard about the weight loss drug Ozempic in the news. It’s another type of semaglutide injection, but it isn’t licensed for weight management in the US or the UK (though it is approved for type 2 diabetes). However, it’s sometimes privately prescribed for weight management ‘off label’ (outside the use it was licensed for). It can cost more than $1,000 a month in the US, and from around £129 a month in the UK via private online clinics.

• How do you take it?
  It comes as an injectable pen, and there are different-strength doses available.

• Results and side effects
  As the active ingredient is semaglutide, the side effect profile and effectiveness is the same as for Wegovy.

Saxenda (liraglutide)

• What is it?
  Like semaglutide, liraglutide is a GLP-1 receptor agonist that was originally developed for type 2 diabetes. It’s used at a higher dose (up to 3mg) for weight management than it is for diabetes.

• How does Saxenda work?
  It acts in a similar way to semaglutide, by suppressing your appetite, so you eat less.

• How do you take it?
  As a daily dose from a pre-filled pen, self-injected under the skin in your stomach, thigh or upper arm. As with semaglutide, it should be taken alongside diet and exercise changes.

• Does it get good results?
  In diabetes trials, liraglutide was associated with significant weight loss of 4.4 to 8.8lbs (2 to 4kg). Patients without diabetes who took liraglutide also lost weight. In a trial of varying daily doses of up to 3mg, weight loss increased with dosage. People saw an average weight loss of 10.5 to 15.8lbs (4.8 to 7.2kg) over 5 months. The results were similar in a 2-year extension (though only half of participants remained at 2 years, with drop-outs mainly due to side effects). In another trial over 56 weeks, patients given a 3mg daily injection had an average weight loss of 17.6lbs (8kg), compared with 5.7lbs (2.6kg) in the dummy (placebo) group.

• Any side effects?
  Common side effects include nausea and vomiting. In one study, these were reported in 37-47 and 12-16 out of 100 participants respectively. Side effects tend to decrease over time, as your body gets used to the medication. Serious but less common side effects include pancreatitis, gallbladder disease and kidney (renal) impairment. If you’re also taking insulin or other diabetes medications, you should monitor your blood sugar (glucose), as the combination may cause it to go too low.

One to watch: tirzepatide for weight loss

• What is it?
  Expected to be licensed for weight management by the FDA in 2023, tirzepatide is predicted to be the biggest blockbuster drug of all time, with sales that could reach $48 billion. (It’s already available for type 2 diabetes, under the brand name Mounjaro.) Costs aren’t available yet, but some industry commentators have predicted it will be similar to Wegovy, at about $1,500 a month.

• How does it work?
  It mimics 2 hormones that help you feel full after eating – GLP-1, plus another called GIP. This reduces appetite and may also improve how your body breaks down fat and sugar.

• How do you take it?
  A weekly injection pen has been used in clinical trials.

• Does it get good results?
  Results from a trial of 2,500 people found it helped patients lose at least 22.5% of their body weight (52lbs/24kg) over 72 weeks. This is the largest weight loss reduction achieved with any weight management drug so far.

• Any side effects?
  Side effects reported in the trial above were similar to those of other weight loss drugs, with nausea, diarrhea, vomiting and constipation commonly reported. They were said to be mild to moderate, and came on mainly when the dose was increased.