Obesity is a complex chronic disease in which abnormal or excessive accumulation of body fat impairs health, writes Dr Jason Seewoodhary.

The Health Survey for England in 2021 estimated that 25.9 percent of adults in England are obese and a further 37.9 percent are overweight but not obese.

Obesity is usually defined as having a body mass index (BMI) of 30 or above. A BMI between 25 and 30 is classified as being ‘overweight’.

Leading on from this there has been a recent surge in the number of patients seeking advice from GPs on whether they may benefit from weight loss injection medications. I’d like to reach out to all patients within our community to empower them with information on what they need to know about these medications.

Weight loss injections are a group of prescribed medications called GLP-1 and GIP-1 analogues.

Examples include trade versions of a generic drug called Semaglutide (Ozempic and Wegovy), Tirzepatide (Mounjaro) and Liraglutide (Saxenda). The active ingredient of these injections is called an “incretin”, which facilitates weight loss by slowing down the emptying of the stomach which makes you feel full earlier, suppresses appetite and food intake by switching off hunger signals within the brain so that you don’t feel hungry, and lowers blood glucose levels.

These medications are taken as an injection into the fat layer just underneath the skin. Most of these medications are administered once-weekly except Saxenda, which is injected daily.

These medications are licensed for use in weight management in conjunction with dietary measures and increased physical activity in individuals with a BMI of 30 or more, or in individuals with a BMI of 27 or more in the presence of at least one weight-related condition such as heart disease, diabetes, high blood pressure, obstructive sleep apnoea, high cholesterol, liver disease, and certain cancers.

In clinical trials, patients taking Ozempic, depending on the dose, lost on average 6.4 kg over a 30 to 56 week period.

In contrast patients taking various doses of Wegovy lost around 16 percent of their body weight, or 16-17kg, after 68 weeks.

Patients taking Mounjaro lost on average four percent of body weight after one month, six percent after two months and 25 percent after one year. Clinical trials have shown patients prescribed Saxenda lost on average five percent of their body weight in eight weeks, seven percent in 16 weeks, eight percent in 24-36 weeks, and nine percent in 56 weeks.

Weight loss injectable medications are usually started at a low dose, which is gradually built-up on a weekly-to-monthly basis in order to reduce the likelihood of side effects. Side effects can include nausea, vomiting, abdominal pain, a change in bowel habit, an increased risk of developing gallstones and swelling of the pancreas.

Any patient concerned about their weight should consult with their GP.

It must be emphasised that these medications are adjuncts to diet, exercise and lifestyle measures and should not be viewed as a primary source of weight loss or a wonder drug.