The obesity crisis: are weight-loss jabs the answer? Five University of Cambridge experts weigh in on the debate
Two thirds of UK adults are overweight or obese.
But weight-loss jabs are now being heralded as revolutionary - with the government even suggesting they could boost the economy by helping obese people get back to work.
Five University of Cambridge experts have shared their views on whether semaglutide-based drugs like Wegovy can really be the solution to the obesity crisis.
At the MRC Epidemiology Unit, Jean Adams, professor of dietary public health, and Martin White, professor of population health research, describe semaglutide as “a great addition to the tool-box that we should use alongside the other tools we know can make effective contributions”.
They say: “If we want to address high levels of obesity and weight-related diseases in our population, we need both to treat people living with those conditions and prevent more people developing them.
“Medicines like semaglutide have proven remarkably effective in helping people lose weight and control type 2 diabetes. However, right now the NHS only recommends semaglutide for weight management for a maximum of two years for people with particularly high body weight that is impacting their health. It is not intended as a way to prevent people from developing these conditions in the first place.
“Some of the most effective approaches to preventing obesity include changing the places in which we live and eat to make it easier for everyone to eat well.
“This includes subsidising healthier foods and taxing less healthy foods, restricting advertising and other promotions for less healthy foods, and making sure that healthier foods are easily available in our neighbourhoods, schools and workplaces.
“Free school meals and Healthy Start vouchers can provide extra support for people who are struggling financially.
“Making sure it's easy to eat well not only helps prevent obesity, it should also help those who lose weight using medicines like semaglutide to stop regaining it when they stop taking the medicine.”
Paul Fletcher, Bernard Wolfe professor of health neuroscience at the Department of Psychiatry, agrees that there is “unlikely to be a single solution to the obesity crisis”.
“Sensible practice, at the clinical and social levels, will integrate a range of approaches helping people to achieve and maintain weight loss. In this respect, Ozempic and drugs like it may prove extremely valuable, particularly in a field where drug treatments have proven limited in their effectiveness or unacceptable in their side effects.”
Ozempic is currently available for the treatment of adults with insufficiently controlled type 2 diabetes mellitus, as an adjunct to diet and exercise.
“There are a range of factors contributing to obesity,” continued Prof Fletcher. “Undoubtedly, in recent decades, the wide and ready availability of aggressively-marketed, highly palatable, energy-dense foods is key.
“There is a high degree of variability in who is vulnerable and who is resistant to the effects of this ‘obesogenic environment’ and this variability is, in large part, genetically determined.
Unfortunately, there are prevailing simplistic and moralistic notions that this vulnerability to obesity lies in some sort of failure of will-power or self-control.
“In fact, research - much of it at the Institute for Metabolic Science in Cambridge - has shown that it relates to the neural circuitry that controls appetite, satiety and the extent to which food stimuli can capture and drive behaviours. Such people may be swimming against a very strong tide, and it is rarely helpful simply to tell them to swim harder.
“If we are prepared to put aside the misplaced moral judgments, we can see drugs like Ozempic as one valuable part of the attempt to redress a balance, giving vulnerable people a greater protection against the effects of an environment that may be markedly more challenging than it is in people whose genetic make-up doesn’t confer this vulnerability.
“As such, we should welcome these drugs as a part of the solution, while at the same time recognising that there is much work to be done in changing the unhealthy food environment.”
Expanding on this, Prof Stephen O'Rahilly, director of the MRC Metabolic Diseases Unit, explains that “obesity occurs when the ‘obesogenic environment’ impinges on people who are genetically predisposed to gain weight”.
So while he agrees that semaglutide drugs are “important new tools to help address the health problems that result from obesity”, he warns: “They aren’t the solution to the obesity crisis.”
Prof O'Rahilly explains: “A a result of pioneering research undertaken at the university, beginning in the 1990s, we now know that the genes concerned principally work in the brain - and that those predisposed to obesity carry variants in these genes that impair the ability of a region called the hypothalamus to sense fullness.
“Our scientists discovered several specific genetic disorders causing severe obesity in childhood. These are now effectively treated by drugs targeted to fix or bypass the underlying defect. The lessons learned in these rarer disorders proved to be applicable to more common forms of obesity.
“Our scientists predicted that the best strategy for finding a drug to treat obesity more generally would be to target the brain centres controlling appetite. Previous attempts had run into safety problems as the drugs affected other aspects of brain function. But the GLP1 receptor agonists, as this new family of drugs is called, don’t have such adverse impacts. Problems with nausea and vomiting can be minimised by careful dose titration.
“The new weight-loss drugs have been shown to confer remarkable health benefits with a good safety profile. We are only at the beginning of this revolution.
“It seems likely that obesity will come to be seen, like high blood pressure and high cholesterol, as a chronic medical condition - the adverse effects of which on disability and premature death can be significantly reduced by the careful use of safe and effective drugs, which will become cheaper.
“But this doesn’t mean that we should not simultaneously be seeking to prevent obesity through making our environments healthier.
“The benefits of a well-balanced diet and an environment that promotes physical activity go well beyond obesity and we owe it to our children to try to provide them with a healthy start in life unburdened by the adverse consequences of excess weight.
“Research at the university was central to providing the data that drove the legislation to establish a soft drinks sugar levy as well as providing invaluable data regarding the effects of the proliferation of fast-food outlets, with this information now being used in urban planning.”
Prof Theresa Marteau, director of the Behaviour and Health Research Unit, notes that more than half the world’s population is expected to be overweight or living with obesity by 2035 and semaglutide only treats this problem, rather than prevening it.
“As a treatment it is remarkably effective, generating average weight losses after 68 weeks of around 12kg. But the cost is huge. In England alone it could double the annual NHS prescription budget of £17bn, with a high rate of weight gain when the drug is stopped. And, like pre-existing treatments including bariatric surgery, it has serious side effects. Not everyone will want it,” she says.
“Tackling the obesity crisis requires us to fix the broken food system that ruins not only our health but also the planetary systems on which all life depends.
“My research focuses on one part of this broken system: the cues or prompts in our everyday environments that, often without our awareness, lead us to consume more energy than we need - mainly from foods high in fat, sugar and salt.
“Interventions that can change these environments can be grouped into those that target the affordability, advertising and availability of less and more healthy foods. We need interventions targeting each of these.”
In terms of availability, companies pay stores to display products in prominent places.
A 2013 study by the unit found sales of alcohol displayed at the end of aisles were between 23 per cent and 46 per cent higher, and for non-alcoholic drinks, between 52 per cent and 114 per cent higher, so restricting the use of aisle ends for alcohol and other less healthy products could help reduce consumption.
“Although based on an observational study, our findings were deemed robust enough to inform policies to reduce consumption of unhealthy food and alcohol in the UK, Australia, USA and UNICEF,” says Prof Marteau.
“The UK government’s 2020 obesity strategy included regulation to restrict where in stores foods high in fat sugar and salt could be displayed. In preparation, an economic impact assessment was conducted. This estimated improved health benefits of £67billion over 25 years from prohibiting placement of such foods on aisle ends and other prominent positions, with a cost to businesses of £5.5billion mainly from lost sales. This prohibition came into force on 1 October 2022.
“This is just one of several interventions that, if implemented as a package, could redesign our everyday environments and reverse the shocking trends in overweight and obesity. And, for those still needing Ozempic and drugs like it, redesigned environments would help maintain their weight-loss post-treatment.”