A lower obesity rate is needed for a better quality of life.

The obesity crisis is directly responsible for 18,000 cases of cancer a year, a major study has found.

One in every 18 diagnoses is down to being overweight, according to researchers at Imperial College London.

Scientists have calculated that being overweight or obese is responsible for 5.6 per cent of cancer diagnoses in Britain, roughly 18,000 cases a year. Another 2,800 are attributed to diabetes much of which is itself linked to obesity, taking a combined impact up to 20,800 cases, 6.4 per cent of the total cancer burden.

The study, funded by the research arm of the NHS and published in the Lancet medical journal, also found diabetes and obesity were together responsible for 800,000 cancers around the world.

Britain is thought to have the highest obesity rates in the EU – with experts warning that so many people were overweight that it was now considered the ‘new normal’.

Scientists have long known poor diets and sedentary lifestyles increased the risk of heart disease. But growing evidence has revealed obesity is also be linked to some forms of cancer. 

The researchers believe having more fat in the body changes the balance of hormones such as oestrogen, testosterone and insulin – which each drive tumour growth. Last year the World Health Organisation published a list of 13 types of cancer linked to excess weight – up from just five previously mentioned.

For instance, being overweight is thought to increase the risk of womb cancer by 50 per cent, oesophageal cancer by 48 per cent, liver cancer by 30 per cent, breast cancer by 13 per cent and ovarian cancer by 6 per cent.

The researchers said if global rates of diabetes and obesity continued to rise, the share of cancers attributable to the combined factors would increase by over 30 per cent in women and by 20 per cent in men by 2035.

Lead author Dr Jonathan Pearson-Stuttard, from Imperial’s School of Public Health, said: ‘In the past, smoking was by far the major risk factor for cancer. But now healthcare professionals should also be aware that patients who have diabetes or are overweight also have an increased risk of cancer.

‘It is vital that coordinated policies are implemented to tackle the shared risk factors and complications of chronic diseases such as obesity and diabetes.’