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What are weight loss injections?

What are weight loss injections?

Weight loss injections are a type of prescription medication for weight loss that can be more effective than weight loss pills. Weight loss pills and weight loss injections are both licensed for people with a BMI of 30 or more (or less than this if you also have certain health conditions).

Daniel Atkinson
Medically reviewed by
Daniel Atkinson, GP Clinical lead
Table of contents
Medically reviewed by
Dr Daniel Atkinson
GP Clinical lead
on November 01, 2022.
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The weight loss injections available are Saxenda, Ozempic and Wegovy. Talk to us if you’re thinking of trying weight loss injections and one of our clinicians will explain how each of them works and answer any questions that you might have.

How do weight loss injections work?

Ozempic and Wegovy contain the active ingredient semaglutide, a component almost identical to the hormone known as GLP-1, which is secreted by your gut when you eat something.

Ozempic works by manipulating your appetite for you to feel full quicker, but also by slowing down the emptying of the stomach, so you can feel full for longer after you eat. It’s often prescribed as a treatment for type-2 diabetes, so if you’re at high risk, or you already have the condition, Ozempic might be the ideal option for you. It’s only licensed for use in diabetes at the moment but it’s expected to change to include weight loss too shortly.

Wegovy also targets the parts of the brain responsible for appetite control. This means that you’ll likely reduce the amount of calories you eat and go on to lose weight. Both Ozempic and Wegovy should be taken alongside a calorie controlled diet and an increase in exercise.

Saxenda uses the active ingredient liraglutide, a synthetic derivative of the hormone GLP-1. This hormone is responsible for your appetite, so by topping up with liraglutide your body will think it’s full faster, and for longer.

Both Saxenda and Ozempic also stabilise blood sugar through insulin production. This can make you feel less cravings, giving you better control over what and how much you eat.

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Do they actually help you lose weight?

Yes, these injection drugs can cause significant and sustained weight loss when used correctly. Usually combined with a reduced calorie diet and an increase in physical activity.

There’s clinical evidence that liraglutide, the active ingredient in Saxenda, helps you lose significant weight sustainably, with the added, unique benefit of improving your glycemic levels.

Wegovy clinical trials found statistically significant weight loss results for participants when compared with a placebo group. The weight loss results were observed in participants irrespective of their age, gender, race, ethnicity and initial BMI.

As mentioned above, like with every weight loss treatment, weight loss injections work best when paired with an exercise and diet plan. This must be a plan that you can carry out long term, as fad diets can help you lose weight faster, but it’ll be harder to maintain that weight loss.

Where do you inject Saxenda?

Injecting Saxenda isn’t too complicated, but you should still see a clinician in person so they can show you exactly how to do it.

Saxenda must be injected subcutaneously (under the skin) on your stomach, thigh, or upper arm. And it must never be injected intravenously or intramuscularly, so it’s better if you have a healthcare professional direct you on how to do it, to make sure that you don’t make a mistake.

You can change the injection site if you like. But it’s only really necessary if you experience any reactions on your last used injection site, such as bruising, pain or irritation.

When should you use Saxenda?

There is no ‘best’ time of day to use Saxenda, simply use it when it’s most convenient for you. But once you’re set on a time you should use it at that same time each day. The time of day and timing of meals doesn’t affect how well it works. But the active ingredient is at its highest amount in your system for about 13 hours, so you should ideally take it in the morning so the effect stays strong all day.

How long does Saxenda stay in your system?

It usually takes about three days for all traces of Saxenda in your body to go away.

The half-life of Saxenda is about 13 hours. The half-life is the amount of time it takes the quantity of the active ingredient in your system to reduce by half. So if you take 3mg of Saxenda at 7am, by 8pm you should only have 1.5mg left in your body.

How long does a Saxenda pen last?

Usually, you’d start a lower dose and gradually increase it until you reach 3mg a day. There are some guidelines on how long this process should last, but it can vary from person to person so it’s better to speak to one of our clinicians and adjust as you go. Usually, you should progress to 3mg within four to five weeks.

So to start with your usage might go a little something like this:

Four pens, lasting for approximately 44 days (around six weeks),

Pen 1 = 17 days
Pen 2 = 8 days
Pen 3 = 7 days
Pen 4 = 6 days

For maintenance use where the maximum dose of 3.0 mg has been reached, one pen will last for six days, which means that a box of five pens will last 30 days.]

Is Ozempic better than Saxenda?

Both semaglutide and liraglutide, the active substances in Ozempic and Saxenda respectively, mimic the hormone GLP-1. Both medications are very similar to the naturally occurring GLP-1 hormone.

Saxenda has been approved as a weight loss medication, and Ozempic is technically a type-2 diabetes medication, but there have been significant results when using it for weight loss, so clinicians have started to prescribe it as an off-label weight loss injection and It’s expected to become a licensed treatment for weight loss soon.

A study that compared the effectiveness of semaglutide, with liraglutide and placebo, found that injecting semaglutide can result in significant weight loss with minimal side effects, and about 37-65% of people who take it will see a decrease of 10% of their excess weight in up to 52 weeks after the treatment starts. In the same time frame, only 25.2% of people taking the highest dose of liraglutide (3mg) achieved the same 10% loss of excess body weight .

It’s important to take into account that the study on the efficacy of semaglutide was done on people without type 2 diabetes, whilst everyone on the study on the efficacy of liraglutide was diagnosed with type 2 diabetes before the study.

What’s the difference between Saxenda and Wegovy?

Saxenda and Wegovy are similar weight loss medications. Saxenda uses the active ingredient liraglutide, whereas Wegovy uses semaglutide. Both active ingredients fall into the same category of medication known as GLP-1. Wegovy and Ozempic are different brand names for the same active ingredient, the doses are slightly different as one is used to treat type 2 diabetes and one is for weight loss.

A course of Saxenda requires a daily injection and the dosage is usually adjusted over time, until you reach the usual recommended dosage of 3.0mg. Alternatively a course of Wegovy just uses a weekly injection and the dosage usually starts at 0.25mg and increases to 2.4mg over a few months.

Wegovy has been shown to be a more effective weight loss medication than Saxenda. This is due to the potency of the active ingredient. Patients using Wegovy may prefer the treatment over Saxenda because it requires a weekly injection instead of a daily injection.

Are weight loss injections safe?

Yes, when used correctly weight loss injections are safe. However, all weight loss treatments can cause side effects.

Ozempic is prescribed for diabetes, but it is safe to use for weight loss. Wegovy is a prescription treatment specifically for weight loss and has undergone rigorous clinical trials.

The side effects of stopping Saxenda are also minimal. Since it’s not an addictive medication, you probably won’t experience any withdrawal. You may also worry about putting the weight back on after you finish your treatment, but there’s no clinical evidence that points to that. You will get your appetite back, but you won’t necessarily put the weight back on simply because you stopped your medication.

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When we present you with stats, data, opinion or a consensus, we’ll tell you where this came from. And we’ll only present data as clinically reliable if it’s come from a reputable source, such as a state or government-funded health body, a peer-reviewed medical journal, or a recognized analytics or data body. Read more in our editorial policy.

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