What are my options for losing weight? Where GLP-1 medicines fit

Which options are for you?

It depends mostly on your BMI and your health. Lifestyle changes are for everyone. Medicines come in at a lower BMI. Procedures and surgery are for much higher weights.

So if your BMI is in the high 20s, the choice is usually between lifestyle changes alone and lifestyle changes plus a medicine. At 170 cm (5 ft 7 in), a BMI of 27 is about 78 kg (12 st 4 lb). NHS surgery usually starts around a BMI of 35 to 40, about 101 to 116 kg (15 st 13 lb to 18 st 4 lb) at the same height.^10,9

The NHS and a medicine's licence use different numbers. The licence says who a medicine can be prescribed for. A private prescriber can use it from a BMI of 30, or 27 with a condition such as high blood pressure, and the licence doesn't lower that for any ethnic group.¹⁰ NHS criteria are stricter: NICE recommends Mounjaro from a BMI of 35 with at least one weight-related condition, and the NHS in England is offering it to the highest-need groups first.^9,13 See Mounjaro on the NHS.

These are points where you and a doctor can start a conversation, not rules that you must or must not have something. Guidelines also look at your health, not just your weight.^9,8

How do the options compare?

In trials, surgery led to the most weight loss. GLP-1 medicines came next, but only while people kept taking them. Lifestyle programmes and pills led to less.

The numbers below come from different trials, with different people. So treat them as rough guides. They are not a direct comparison. "Weight lost" is the average share of starting body weight.

Each option in detail. Weight lost is the average share of starting weight.

We show only official prices: NHS prescription charges and the maker's list price published by NICE. Private clinics and pharmacies set their own prices, and we don't list or compare them. GLP-1 and orlistat costs repeat every month.

In the medicine trials, the dummy-injection groups lost 2.4% and 3.1%, or about 2–3 kg.^4,5 These are averages, and results vary from person to person. In those trials, about 14 in 100 people on semaglutide and 9 in 100 on tirzepatide lost less than 5% of their weight.^4,5

Can food and activity changes alone help?

Yes, for many people. Structured programmes helped people lose around 6–9% of their weight, and cut their risk of diabetes.

One large trial, Look AHEAD, followed 5,145 adults with type 2 diabetes.¹ The programme set a calorie target and about 3 hours of activity a week, with frequent group and one-to-one sessions.¹ People lost 8.6% of their weight in the first year, against 0.7% with usual care.¹ After about 10 years, they were still 6.0% lighter, against 3.5%.¹

In the US Diabetes Prevention Program, 3,234 people with high blood sugar (prediabetes) took part.²⁶ The lifestyle group lost 5.6 kg (about 12 lb) on average over about 3 years, against 0.1 kg on a dummy pill.²⁶ Their rate of new diabetes was 58% lower: 4.8 cases per 100 people a year, against 11.0.²⁶

Food: how much to cut

To lose weight, NICE says you need to take in less energy than you use, whether by eating less fat, fewer carbohydrates or another method.²⁵ US guidelines put a number on it: about 500–750 calories a day less than your body uses.²⁸ That's a cut from what you need, not a daily total. Someone whose body uses 2,200 calories a day would eat about 1,450–1,700.

NICE advises against restrictive diets that aren't nutritionally balanced. Low-calorie diets of 800 to 1,200 calories a day should only be used with specialist support, and for no more than 12 weeks.²⁵

Protein: the part most people miss

When you lose weight, some of it is muscle. Too little protein makes that worse, and a smaller appetite on a GLP-1 medicine makes protein harder to get.²⁹

The same advisory says to pair protein with strength exercise at least 3 times a week, plus at least 150 minutes of moderate activity like brisk walking.²⁹ If you have kidney disease, ask your doctor before raising your protein.

What to put on the plate

NICE points people to the NHS Eatwell Guide for a balanced diet over the long term.²⁵ You don't need every meal to match it; aim for the balance over a day or a week.³⁰

Activity and support

Activity. The NHS advises adults to do at least 150 minutes of moderate activity a week, like brisk walking, or 75 minutes of vigorous activity, like running. It adds strengthening activities on at least 2 days a week.³¹ For people on a GLP-1 medicine, the US advisory above suggests strength exercise at least 3 times a week.²⁹ NICE says people who have lost weight may need 60 to 90 minutes of activity a day to keep it off.²⁵ Speak to your GP first if you haven't exercised for a while or have a medical condition.³¹

Support. NICE says that when a weight-loss medicine is prescribed, you should also be offered support with diet, activity and behaviour.⁹ WHO also says diet and activity programmes may be offered alongside GLP-1 medicines.³²

What about pills, and other medicines that lower weight a little?

One older weight-loss pill, orlistat, is widely used in the UK. It helps a little. Some diabetes medicines also lower weight a little.

Orlistat stops about a third of the fat in your food from being absorbed; it passes out in your poo.³ It's available as Xenical on prescription, or at a lower dose as Alli or Orlos from a pharmacy.³ On the NHS it's prescribed at a BMI of 30 or more, or 28 or more with a weight-related condition such as type 2 diabetes or high blood pressure.^3,9 In a 4-year trial, people on orlistat lost 5.8 kg, against 3.0 kg on a dummy pill.² Fatty or oily poo, needing the toilet urgently and wind are common.³ The NHS says not to carry on past 3 months if you haven't lost 5% of your weight.³

Metformin is a diabetes medicine, not a licensed weight-loss one. In the Diabetes Prevention Program it led to 2.1 kg of loss on average.²⁶ An international PCOS guideline says doctors should consider it for women with PCOS (polycystic ovary syndrome) and a BMI of 25 or more.³³

SGLT2 inhibitors, such as dapagliflozin, lead to modest weight loss. Across 116 trials, people lost about 1.8 kg more than on a dummy pill.³⁴

Naltrexone–bupropion (Mysimba) is a combination pill for weight. NICE does not recommend it for NHS use.³⁵

Where do GLP-1 medicines fit?

They lead to more weight loss than pills or lifestyle alone. But they are a long-term treatment, and most of the weight returns if you stop.

Semaglutide (Wegovy) acts like the gut hormone GLP-1.²⁰ Tirzepatide (Mounjaro) acts on GLP-1 and a second gut hormone, GIP.⁵ Guide 2 explains how they work. In every trial below, people also followed a diet and activity plan.^4,5

Average weight lost in each trial. Kilograms are for someone who starts at 90 kg (14 st 2 lb).

Only the last trial compared the two medicines directly; the others each tested one medicine against a dummy injection, so don't compare across them.

The NHS 5% check. NICE says that if less than 5% of your starting weight has gone after 6 months, you and your prescriber should consider stopping (semaglutide) or decide whether to carry on (tirzepatide).⁹

Tablets. Wegovy tablets (oral semaglutide) were licensed for weight in June 2026, and Foundayo (orforglipron) in August 2026.^39,40 The trial results on this page are for weekly injections.^4,5

What happens when you stop. A year after stopping semaglutide, trial participants had regained about two-thirds of the weight they lost.⁶ In a tirzepatide trial, everyone first took the medicine for 36 weeks and lost about 21% of their weight.⁴¹ Then some were switched to dummy injections. Over the next year, their weight went up by 14% of what they weighed at the switch.⁴¹ For someone who weighed 85 kg (13 st 5 lb) by then, that is about 12 kg (85 × 0.14 = 11.9). Those who stayed on tirzepatide lost a further 5.5% over the same year.⁴¹ Guide 9 covers stopping.

Cost. On the NHS you pay the normal prescription charge: £9.90 per item in England, and nothing in Scotland, Wales or Northern Ireland.^16,17,18,19 In England, people with diabetes treated with medicines can get an exemption certificate, so they don't pay.⁴² Privately, you pay the full price. NICE publishes Mounjaro's list price for a 4-week pen: £133 for 2.5 mg, £180 for 5 mg, £255 for 7.5 mg and 10 mg, and £330 for 12.5 mg and 15 mg, before VAT.¹³ Private services set their own prices on top. Guide 6 covers costs and safe ways to get them.

Who it's for. UK licences allow these medicines from a BMI of 30, or 27 with a weight-related condition.^10,40 On the NHS, Wegovy and Saxenda for weight are only given in specialist weight services, for up to 2 years, and Mounjaro is being rolled out in stages through GPs in England.^9,43,13 That is a point where you and a doctor can start talking about it. It does not mean you should take one. Guide 4 covers who should and shouldn't take them.

Who is weight-loss surgery for in the UK?

Surgery is for people with a higher BMI, often with a health condition that weight loss could improve. It gives the largest, longest-lasting loss, but it is a major operation.

NHS thresholds

NICE says adults should be offered a referral to a specialist weight service to see whether surgery suits them if they:⁹

• have a BMI of 40 or more, or
• have a BMI of 35 to 39.9 with a significant health condition that could improve with weight loss, such as type 2 diabetes, high blood pressure, sleep apnoea or fatty liver, and
• agree to long-term follow-up after surgery, such as yearly reviews for life.⁹

People with type 2 diabetes diagnosed in the past 10 years may get a faster assessment: offered from a BMI of 35, and considered from 30.⁹ For people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background, NICE says to consider these thresholds 2.5 lower.^9,24 Availability varies across the UK.²⁴ Newer guidance from US and international surgeons (2022) offers surgery from a BMI of 35, or 27.5 for Asian people.⁸

Results

A Swedish study followed over 4,000 people. Gastric bypass led to 32% loss at its peak, and 25% after 10 years.⁷ Gastric banding, which puts a band around the stomach, led to less: 20% and 14%.⁷ People who had surgery were less likely to die during the study than similar people who didn't.⁷

Diabetes. In a US trial, 5 years after surgery, 29 in 100 (bypass) and 23 in 100 (sleeve) had near-normal blood sugar.⁴⁶ With medicines alone, it was 5 in 100.⁴⁶ In a Finnish trial, about 1 in 4 to 1 in 3 had diabetes in remission at 10 years.²³

Risks

• Death around the time of the operation is rare: between 3 in 10,000 and 2 in 1,000.⁸
• Over 10 years, 16–19 in 100 needed another operation.²³
• Acid damage to the food pipe was found in 31 in 100 after a sleeve, against 7 in 100 after a bypass.²³
• Other risks include blood clots, a leak from the stomach, gallstones and excess skin.⁴⁷
• NICE says the surgical service should follow you up for at least 2 years, then your GP should check your nutrition at least once a year for life.⁹

Cost. Surgery may be available on the NHS if you meet the criteria. You can also pay privately, which the NHS says can be expensive; we found no official private price.²⁴

What are gastric balloons and endoscopic sleeves?

Both are done through the mouth with a camera tube (an endoscope), without cutting the skin.^11,12 Neither removes any part of the stomach.^11,12

Gastric balloon. A balloon is placed in the stomach using the endoscope. In a US trial, it was removed after 6 months.¹¹ People lost 10.2% of their weight by then, against 3.3% with lifestyle alone.¹¹ By 12 months, loss had eased to 7.6%.¹¹ Feeling sick (87 in 100) and vomiting (76 in 100) were common, and 19 in 100 had it taken out early.¹¹ The trial included adults with a BMI of 30 to 40.¹¹

Endoscopic sleeve gastroplasty (ESG) reshapes the stomach from the inside.¹² In a trial at nine US centres, adults with a BMI of about 30 to 40 (class 1 or 2 obesity) took part.¹² They lost 13.6% at 1 year, against 0.8% with lifestyle alone.¹² Serious problems happened in 2 in 100 people.¹² In 2024, NICE said ESG can be used to treat obesity in adults, chosen by a specialist weight team and done only in specialist centres.²²

How does the NHS build up care?

There is no single fixed order. Options can be combined, and diet and activity stay part of every plan.^9,32

NHS weight services are often described in tiers. Local behavioural services are sometimes called tier 2. Specialist services, run by a team of doctors, dietitians and psychologists, include tier 3 and tier 4.⁴⁸ Here is a simple picture of how the options fit:

For example, NICE says medicines may be used to keep weight steady or lower it while someone waits for surgery, if the wait is long.⁹ For people with recent type 2 diabetes and a BMI of 30 or more, a faster surgery assessment may be considered.⁹

Questions people ask