Weight loss treatment and medications
www.nesta.org.uk/project/weight-loss-treatment-and-medications/
www.nesta.org.uk/project/weight-loss-treatment-and-medications/
In the UK, two in three adults live with excess weight or obesity. Obesity increases the risk of major health conditions, including cardiovascular disease, type 2 diabetes, and some cancers. It can reduce quality of life and carries significant costs for individuals, the NHS and the economy.
Action on obesity is needed to improve the health of the nation. The doubling in obesity rates over the last 30 years is driven by changes in our food environment, by which we mean the food around us and how it is promoted, advertised and displayed, how much it costs and how convenient it is to buy. Evidence shows that transforming the food environment is the most effective, scalable way to prevent and reduce obesity across the population. However, for individuals living with obesity who face the greatest risk to their health, effective treatment also has an important role to play. This can include structured behavioural weight-management programmes, total diet replacement programmes, bariatric surgery and weight-loss medications. Of these treatments, glucagon-like peptide-1(GLP-1) based weight-loss medications have garnered significant interest and seen a huge growth in uptake in just a few years.
The emergence of GLP-1 based weight-loss medications is a major breakthrough in obesity treatment. They help people achieve substantial weight loss, while growing evidence suggests they can deliver wider health benefits and potentially significant economic gains. However, despite their rapid adoption, the evidence also points to some important limitations. Many people experience side effects which limit their ability to use the medication and there are high rates of discontinuation, meaning long term benefits are not always realised. People also regain weight rapidly after stopping treatment and faster than after behavioural weight-management programmes. In one major trial, participants regained around two-thirds of the weight they had lost within a year of stopping treatment. And, at current costs, delivering GLP-1 medications at the scale needed to meaningfully shift obesity rates would be undeliverable due to prohibitive costs to the NHS.
These constraints are already reflected in NHS access. It is right that people with the greatest clinical need are prioritised, but the planned rollout is slow relative to the number of people who could benefit. NHS England plans to prioritise around 220,000 people in the first three years of a rollout that could take up to 12 years; a fraction of the 3.4 million people who meet NICE eligibility criteria. In the meantime, many people are paying privately, risking a two-tier system in which access to treatment depends on ability to pay. This compounds longstanding inequalities in obesity treatment: access to specialist weight-management services already varies substantially across England, with some of the most deprived areas having the most limited provision. Unequal access to effective treatment risks widening existing health inequalities.
Obesity treatments work in different ways and vary substantially in the amount and durability of weight loss they achieve. A person’s eligibility for a given treatment depends on the type of treatment, their BMI and weight-related health conditions, where they live and whether care is NHS-funded or private.
Bariatric surgery: includes operations such as sleeve gastrectomy and gastric bypass, which alter the stomach and gut to reduce appetite and food intake and is generally only considered for people with more severe or complex obesity. It has the strongest evidence for long-term weight loss, with people remaining around 18% below their starting weight after 20 years.
GLP-1 medications: reduces appetite and increase feelings of fullness by mimicking gut hormones involved in regulating hunger. Eligibility criteria vary depending on whether they are prescribed by the NHS or privately, where you live in the UK and between the different drugs. In clinical trials, depending on dosage, tirzepatide (Mounjaro) produced average weight loss of 20.9% over 72 weeks, while semaglutide (Wegovy) produced 14.9% over 68 weeks. However, weight regain is common after treatment stops: around 60% of weight lost is regained within a year.
Total diet replacement programmes: replace conventional food for around 8-12 weeks with nutritionally complete low-calorie products, followed by food reintroduction and behavioural support. They are generally offered to people at greater clinical risk and with professional support. In a UK trial, participants lost an average of 10.7 kg after one year, with 45% losing at least 10% of their starting weight.
Behavioural weight management programmes: support changes to diet, physical activity and other behaviours through coaching, goal-setting and monitoring and are the most widely available form of treatment. Average weight loss is generally more modest: in the NHS Digital Weight Management Programme participants lost 2.2 kg on average, rising to 3.9 kg among programme completers.
Effective treatment is an important part of the response to obesity. There is strong evidence supporting the case for widening access to treatment, including but not limited to GLP-1 medications. Effective treatment can deliver substantial health benefits, savings to the NHS and generate wider economic returns. Expanding NHS provision would help to ensure that these benefits reach those with the greatest clinical need, rather than being concentrated among people who can access treatment privately. But even with greater access, treatment has limitations and will only ever reach the part of the population eligible for care.
Treating obesity does not address its underlying causes. The increase in obesity since the 1990s is not the result of a collective loss of willpower to resist unhealthy food, but the effects of the food environment in which we live and work, which makes less healthy choices the default.
That is why the policy the government announced in 2025 - the healthy food standard - could be transformational. By requiring large food businesses to report on the healthiness of their sales and setting targets to improve them, the policy could make healthier choices the easier choices, and help reduce obesity across the population. This matters for treatment too. A healthier food environment could help people to eat well and support efforts to maintain the benefits of effective obesity treatment.
Treatment and prevention are not competing priorities - progress on one supports the other. Expanding equitable access to effective treatment should go hand in hand with long-term action to reshape the food environment and reduce the number of people developing obesity in the first place.
