Obesity in the United Kingdom is a significant contemporary health concern, with authorities stating that it is one of the leading preventable causes of death. In February 2016, former Health Secretary Jeremy Hunt described rising rates of childhood obesity as a "national emergency". The National Childhood Measurement Programme, which measures obesity prevalence among school-age pupils in reception class and year 6, found obesity levels rocketed in both years groups by more than 4 percentage points between 2019–20 and 2020–21, the highest rise since the programme began. Among reception-aged children, those aged four and five, the rates of obesity rose from 9.9% in 2019–20 to 14.4% in 2020–21. By the time they are aged 10 or 11, more than a quarter are obese. In just 12 months, the rate is up from 21% in 2019–20 to 25.5% in 2020–21.

The 2024 Health Survey for England (HSE) found 30% of adults over 16 had clinical obesity, with a Body Mass Index (BMI) greater than 30. 70% of men and 62% of women were overweight with a BMI of 25-30, whilst the proportion of obesity was higher amongst women at 31% than men (29%). In the span of 31 years, mean weight increased for men and women alike, from 78.9kg to 86.2kg (9.25% increase), and 66.6kg to 73.0kg (9.61%) respectively. For children aged 2-15, 26% were either overweight or obese, within which 15% were confirmed to be clinically obese.

Rising levels of obesity are a major challenge to public health. There are expected to be 11 million more obese adults in the UK by 2030, accruing up to 668,000 additional cases of diabetes mellitus, 461,000 cases of heart disease and stroke, 130,000 cases of cancer, with associated medical costs set to increase by £1.9–2.0B per year by 2030.

Combining three years of data (2012, 2013, and 2014) Public Health England identified Barnsley, South Yorkshire as the local authority with the highest incidence of adult obesity (BMI greater than 30) with 35.1%. Data from the same study revealed that Doncaster, South Yorkshire was the local authority with the highest overall excess weight with 74.8% of adults (16 years and over) with a BMI greater than 25. In previous Public Health England studies based on 2012 data, Tamworth in Staffordshire had been identified as the fattest town in England with an obesity rate of 30.7%.

Causes

Causes cited for the growing rates of obesity in the United Kingdom are multiple and the degree of influence of any one factor is often a source of debate. At an individual level, a combination of excessive food energy intake and a lack of physical activity is thought to explain most cases of obesity. Reduced levels of physical activity due to increased use of private cars, desk-bound employment, a decline in home cooking skills and the ready availability of processed foods high in sugar, salt and saturated fats, are variously cited as contributing factors.

Patterns of food consumption outside the home

Media attention given to celebrity British chefs such as Gordon Ramsay, Heston Blumenthal, Marco Pierre White and many others with television shows and books encouraging home produced meals may have had a limited short-term impact on the growth of fast-food chains such as McDonald's and Burger King. Other fast-food outlets, high street bakeries, and chain coffee shops offering hot drinks with sugar levels over three times the daily recommended limit have nonetheless continued to rapidly expand. A 2015 University of Cambridge study reported that the total number of takeaway restaurants including fried chicken, fish and chips, pizza, kebab, Indian and Chinese takeaway shops has risen by 45% over the preceding 18 years. Similarly, popcorn, although a healthy snack by itself, becomes a high calorie snack once topped with butter and various other flavourings offered by cinemas. For example, a large sweet popcorn at Cineworld has 1,180 calories. Popularity for the microwavable snack has increased dramatically over the 5 years to 2016, with total sales increasing by 169%.

Professor Jimmy Bell, an obesity specialist at Imperial College London, has stated that contrary to popular belief, the people of the United Kingdom have not become greedier or less active in recent years. One thing that has changed is the food that they eat, and, more specifically, the sheer amount of sugar they ingest. "We're being bombarded every day by the food industry to consume more and more food. It's a war between our bodies and the demands our body makes, and the accessibility that modern society gives us with food."

Effects

Being overweight or obese increases the risk of illnesses, such as type 2 diabetes, high blood pressure, heart disease, stroke, as well as some forms of cancer. In the United Kingdom, obesity and a BMI of 30 to 35 has been found to reduce life expectancy by an average of three years, while a BMI of over 40 reduced longevity by eight to 10 years.

According to a report published by the Commons Health Select Committee in November 2015, treating obesity related medical conditions costs the National Health Service (NHS) £5 billion a year and has a wider cost to the economy of £27 billion. A study published by two McKinsey researchers in the same year estimated costs to the United Kingdom economy of £6 billion ($9.6 billion) annually in direct medical costs of conditions related to being overweight or obese and a further £10 billion in costs on diabetes treatment. The cost of obesity and diabetes treatment in the NHS is equivalent to the United Kingdom's combined budget for the police and fire services, law courts, and prisons; 40 percent of total spending on education; and about 35 percent of the country's defense budget.

British sperm quality has been negatively affected by obesity.

Operational issues Obese people often have to be moved by firefighters, as they are beyond the capacity of the ambulance service. From January 2013 to May 2015, 5,565 firefighters attended 1,866 "bariatric rescues" in the UK. Each call costs around £400. The National Health Service has only a limited capacity for scanning obese people, meaning that obese patients often have to be sent to distant hospitals to be scanned. Hospitals in Scotland installed 41 oversized mortuary fridges between 2013 and 2018 to cope with larger corpses.

Tackling obesity Various groups including government, food and health care professionals have made attempts to highlight and address the causes and growing problem of obesity in the United Kingdom.

School meals In 2005, British chef Jamie Oliver began a campaign to reduce unhealthy food choices in British schools and to get children more enthused about eating lower calorie nutritious food instead. Oliver's efforts to bring radical change to the school meals system, chronicled in the series Jamie's School Dinners, challenged the junk-food culture by showing schools they could serve healthy, nutritious and cost-efficient meals that children enjoyed eating. The British Government and Prime Minister Tony Blair promised to take steps to improve school dinners shortly after the programme aired. The programme prompted 271,677 people to sign an online petition on the Feed Me Better website, which was delivered to 10 Downing Street on 30 March 2005. As a result, the government added an extra £280 million ($316m USD) to help with the school meals plan. Currently fried foods are only allowed to be served twice a week and soft drinks are no longer available. However, there are no limits on the amount of sugar that can be legally consumed in the School Food Standards. The Department for Education and Skills created the, now defunct, School Food Trust, a £60 million initiative to provide support and advice to school administrators to improve the standard of school meals. Sugarwise found that some children have been exceeding the recommended sugar limits at schools, and in June 2019, introduced a certification scheme for school catering.

Recommendations by medical professionals In 2013, 220,000 doctors in the United Kingdom united to form what they call a 'prescription' for the UK's obesity epidemic. The report presented an action plan for future campaigning activity, setting out 10 recommendations for healthcare professionals, local and national government, industry and schools which it believed would help tackle the nation's obesity crisis.

Recommendations included: Food-based standards to be mandatory in all UK hospitals A ban on new fast-food outlets being located close to schools and colleges A duty on all sugary soft drinks, increasing the price by at least 20%, to be piloted Traffic light food labelling to include calorie information for children and adolescents – with visible calorie indicators for restaurants, especially fast-food outlets £100m in each of the next three years to be spent on increasing provision of weight management services across the country A ban on advertising of foods high in saturated fats, sugar, and salt before 9pm Existing mandatory food- and nutrient-based standards in England to be statutory in free schools and academies

Action on Sugar, a registered UK charity and lobby group, was also formed in 2014 by a group of medical specialists concerned about sugar and its impact on health. Research by the group has highlighted the amount of added sugar contained in both processed food as well as drinks sold by national retailers such as Starbucks and Costa Coffee. Despite this, the proposed sugar tax was squarely aimed at high-sugar drinks, particularly fizzy drinks, which are popular among teenagers. Pure fruit juices and milk-based drinks were excluded and the smallest producers had an exemption from the scheme.

Government initiatives In October 2011, British Prime Minister David Cameron told reporters that his government might consider a Fat tax as part of the solution to the United Kingdom's obesity problem. A Public Health Responsibility Deal was subsequently announced in 2012 with voluntary pledges from the food industry and local business to promote healthy eating and physical activity. The Public Health Responsibility Deal has been hailed by members of the UK's Food and Drink Federation and the Department of Health, but research published in 2015 by the London School of Hygiene & Tropical Medicine questioned the effectiveness of the voluntary agreement. Policy based initiatives to improve diet, such as food pricing strategies, restrictions on marketing and the reduction of sugar intake, do not form a part of the pledges agreed by the food industry under the terms of the Public Health Responsibility Deal.

The government made efforts to use the London 2012 Summer Olympics to help tackle obesity and inspire people into a healthy active lifestyle. Health Secretary Alan Johnson set up Olympic themed Roadshows and mass participation events such as city runs. A £30 million grant was also issued to build cycle paths, playgrounds, and encourage children to cut out snacks.

As a part of the London 2012 legacy, Prime Minister David Cameron also announced an annual £150 million ($227-USD) boost for school sport. The funding is "ring-fenced", meaning it can only be spent on sports activities such as after school clubs, coaching, and dedicated sports programmes. Prompting criticism about mixed messaging, Official sponsors of the 2012 London Olympics included McDonald's, Coca-Cola, and Cadbury.

In the 2016 United Kingdom budget, the British Government announced the introduction of a sugar tax on the soft drinks industry, which came into effect in April 2018. Beverage manufactures are taxed according to the volume of sugar sweetened beverages they produce or import. The measure would generate an estimated £520 million a year in additional tax revenue to be spent on doubling existing funding for sport in UK primary schools.