I want to lose a few pounds before an event. Should I try a GLP-1?

Why isn't it meant for this?

These medicines treat a disease. They aren't meant for fine-tuning your weight.

Wanting to look and feel your best on a big day is completely normal. But the MHRA says GLP-1 medicines should only be used if you are overweight or have diabetes, "and not if you want to lose weight for aesthetic or cosmetic purposes".²

Here are the lines that matter in the UK:

• The licence. Wegovy and Mounjaro are licensed for weight management in adults with a BMI (body mass index, your weight compared with your height) of 30 or more, or 27 to under 30 with at least one weight-related health problem, such as high blood pressure.³
• NICE's healthy range. NICE, which writes guidance for the NHS in England, counts a BMI of 18.5 to 24.9 as healthy. Overweight starts at 25, or at 23 for people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds.⁴
• The NHS. NHS access is far narrower than the licence. In England, GPs prescribe Mounjaro for weight first to people with a BMI of 40 or more and several weight-related conditions.¹¹
• Ozempic. In the UK it is licensed for type 2 diabetes only, not for weight loss.²

So if you're in the healthy range, or just above it, these medicines aren't licensed for you.

Would it even work in time?

Not really. The dose goes up slowly, over about 4 months.

Wegovy starts at 0.25 mg and steps up every 4 weeks. It reaches the full dose of 2.4 mg after 16 weeks.¹

Feeling sick and diarrhoea were the most common side effects in STEP 1, the main semaglutide weight trial. People there got either the medicine or a dummy injection with no medicine in it. More people stopped because of stomach effects on the medicine.⁵

Out of every 100 people, how many stopped because of stomach effects:

Bars are drawn on a scale up to 10 in 100.

Not ideal in the weeks before a celebration. The MHRA also reminds people that these medicines are not a quick way to lose weight.²

What happens after the event?

The weight usually comes back once you stop.

A year after stopping semaglutide, people followed up from STEP 1 had regained about two-thirds of the weight they lost.⁶ Most of their gains in blood pressure, sugar and cholesterol faded too.⁶

What about the fakes?

Fake pens exist in the UK. Buying without a proper consultation, from unregulated sellers, raises the risk of getting one.

• The WHO has found falsified Ozempic in Brazil, the UK and the US. Fakes may be missing the medicine, or contain a different one, such as insulin.¹²
• The MHRA has warned about fake Ozempic and Saxenda pens found in the UK.⁸ In February 2026 a falsified Mounjaro 15 mg pen was supplied through a UK online pharmacy.⁷
• The MHRA says never to buy from beauty salons or social media, and that powders in vials you mix yourself are not authorised.²

So what works instead?

A plan built around food and movement, started as early as you can.

The WHO says medicines alone won't solve weight problems. Healthy eating and physical activity remain the base of treatment.⁹ Guide 3: Your options sets out what the evidence says about each option.

And if your weight is affecting your health, that's a different conversation. Guide 1: Weight and health helps you check where you stand.

What to read next, in order

These three guides go deeper. Each one ends with a link to the next, so you can read them one after another.

1. 1Should I consider a GLP-1? And when not toGuide 4 of 9DecideThe section on losing a few pounds: who these medicines are for, and who they're not for.
2. 2Your options, and where medicines fitGuide 3 of 9DecideFood, activity and other options, with what the evidence says about each.
3. 3Stopping and the long termGuide 9 of 9Live with itWhat happens to weight, and to your body, when people stop.