Obesity costs the world almost the same amount of money as smoking and costs significantly more than alcoholism, researchers have claimed.

According to a new research paper by the McKinsey Global Institute (MGI), more than 2.1 billion people - 30% of the world's population - are now overweight or obese. That figure is almost 2.5 times higher than the number of people who are undernourished globally.

Obesity is now estimated to cost the world $2 trillion per year (almost €1.6 trillion). That is almost the same as smoking, which costs $2.1 trillion per year, and armed violence, war and terrorism, which also costs the world $2.1 trillion a year.

The obesity figure also comes in far ahead of alcoholism, which costs the world $1.4 trillion annually.

The paper states that around 5% of all annual deaths worldwide are as a result of obesity, yet the problem is preventable.

"If the prevalence of obesity continues on its current trajectory, almost half of the world's adult population will be overweight or obese by 2030. However, much of the global debate on this issue has become polarised and sometimes deeply antagonistic. Obesity is a complex, systemic issue with no single or simple solution," the MGI said.

The research paper included details of an independent review of 74 different interventions that are currently being discussed or piloted somewhere in the world. The interventions studied included subsidised school meals, restrictions on advertising certain foods and nutrition labelling.

In attempting to ascertain a potential strategy to deal with obesity, the paper found that no single intervention is likely to have a significant impact overall and instead many different interventions need to be considered.

It also found that almost all of the interventions are cost effective, as ‘savings on healthcare costs and higher productivity could outweigh the direct investment required by the intervention'.

The paper also noted that while personal responsibility is essential, there also need to be changes made in relation to societal norms. For example, default portion sizes need to be reduced and marketing practices need to change.

Meanwhile, it also emphasised that no individual sector can tackle obesity on its own.

"Not governments, retailers, consumer goods companies, restaurants, employers, media organisations, educators, healthcare providers, or individuals. Capturing the full potential impact requires engagement from as many sectors as possible," the paper found.

It added that tackling this issue ‘will not be easy'.