Weight loss drugs could boost the economy in England by helping to get obese people back into work, the government has suggested.

But NHS experts have warned that treatment services are already overstretched to cope with the unprecedented demand from patients wanting these medicines.

There are two drugs on the market – semaglutide, marketed under the brand name Vegovy, and tirazepide, sold under the brand name Monzaro. Semaglutide is also used in the diabetes treatment Ozempic.

Both Vegovi and Monjaro are given as weekly injections through a pre-filled pen that can be self-administered in the upper arm, thigh, or abdomen.

They work as appetite suppressants by mimicking a hormone called glucagon-like peptide-1 (GLP-1).

This intestinal hormone is released after eating, and normally makes people feel full.

Monjaro also affects another hormone, glucose-dependent insulinotropic polypeptide (GIP), which affects metabolism and helps regulate energy balance.

Patients usually start with a low dose which is gradually increased until they reach a higher maintenance dose.

People taking these medications usually start losing weight within a few weeks.

Clinical trials show that – when combined with changes to their diet, exercise and behavioral support – Wegovi users can lose more than 10% of their body weight after a year of treatment.

Other tests show that Monjaro users could lose even more. But it is difficult to compare the two treatments and importantly, users of either may gain the weight back after stopping treatment.

• Wegovi, the ‘Viagra’ of weight loss drugs

At the moment, only Wegovi is available on the NHS in England, Wales and Scotland, but Monjaro will also be introduced soon.

Wegovi can only be prescribed by specialist weight management services and access to these is restricted.

To qualify, adults must have at least one pre-existing weight-related health condition such as high blood pressure and obesity.

People with heart disease who are overweight but not very obese may also be prescribed the drug.

According to NHS guidelines, patients must follow a diet and physical activity programme, and the medicine should only be prescribed for a maximum of two years.

There have been reports of shortages of Wegovi, although manufacturer Novo Nordisk says the NHS has conserved supplies.

Prime Minister Sir Keir Starmer told the BBC the government is proposing to give obese unemployed people in England the chance to lose weight. Could be “very important” for the economy and individuals’ health,

But weight loss experts have warned that NHS obesity services are already struggling to cope with demand for these drugs, and the injections should only be used as part of a comprehensive treatment plan.

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Both medicines can be purchased privately, including from some supermarkets, chemists and high-street clinics.

The pen usually costs between £200 and £300, depending on the dosage.

Medicines should not be purchased from non-regulated sources.

A BBC investigation in November 2023 found that online sellers were offering semaglutide as a medicine without a prescription.

It was also found that this drug was also being given in beauty salons in Manchester and Liverpool.

• Promotion of weight loss injections fuels online black market
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The most common side effects are feeling sick, vomiting, bloating, constipation and diarrhea. Some people complain of hair fall.

For many people the side effects are manageable and go away with time; Others say they stopped taking medications because of them.

In rare cases, serious side effects may include gall bladder and kidney problems and depression.

Experts warn that if the drugs are misused, for example, taken as a quick fix to lose a few pounds or purchased from unregulated online sellers, the complications can be worse.

Doctors say they have seen dangerous, life-threatening complications like inflammation of the pancreas in such cases.

That is why experts say that they should be used only under medical supervision.

• Top doctors worried about misuse of weight loss drugs

There is always a risk that someone will gain weight again because stopping treatment means their normal food cravings will return.

That’s why experts recommend that people make changes to their diet and exercise regimen during treatment to ensure that healthy habits are maintained.

Health Secretary Wes Streeting has warned about the danger of people developing a “dependence culture” on these drugs.

and this research suggests Most people gain most of the weight back within a year of stopping.

The term obesity describes a person who has excess fat in their body.

In Britain it is estimated that one in four adults is obese.

The standard way to classify people’s weight is to calculate their body mass index, or BMI, which means dividing an adult’s weight in kilograms by the square of their height in meters.

For most adults, if your BMI is:

• Below 18.5 – you are in the underweight category
• 18.5 to 24.9 – You are in the healthy weight range
• 25 to 29.9 – You are in the overweight category
• 30 to 39.9 – You are in the obese category
• 40 or more – you are in the severely obese category

People with Asian, Chinese, Middle Eastern, Black African or African-Caribbean family backgrounds need to use lower BMI scores to measure overweight and obesity:

• 23 to 27.4 – overweight
• 27.5 or more – obesity

BMI has some limitations because it measures whether a person is overweight but not overweight.

For example, people who are very muscular may have a high BMI even without having much fat.

But for most people, it’s a useful indicator of whether their weight is healthy.