Nearly 30% of the world population is overweight.

More than 2.1 billion people globally -- or nearly 30 percent of the world's population -- are now overweight or obese, with the figure set to rise further by 2030, according to a study published Thursday.

Obesity is now blamed for around 5 percent of all deaths worldwide and has a similar negative effect on the global economy to smoking and armed conflict, according to the report by consultants McKinsey Global Institute.

The study predicted that almost half of the world's adult population will be overweight or obese by 2030.

It called for a "coordinated response" from governments, retailers and food and drink manufacturers, arguing that targeted action could bring 20 percent of obese people back to normal weight within a decade.

"Obesity is a major global economic problem caused by a multitude of factors," it said.

"Today obesity is jostling with armed conflict and smoking in terms of having the greatest human-generated global economic impact."

The report identified 74 interventions that it argued will help tighten waistlines around the world.

Recommendations include limiting the size of portions in packaged fast food, parental education and introducing healthy meals in schools and workplaces.

According to the report, obesity now costs the global economy $2 trillion in healthcare and lost productivity -- or 2.8 percent of global GDP -- $100 billion less than both smoking and armed conflict.

Britain provided the report's main case study, and was found to have three percent of its GDP wiped off each year due to obesity, the biggest drag on the country's economy after smoking.

The combined annual cost of obesity-linked healthcare and lost output reaches £47 billion ($73.8 billion, 58.7 billion euros).

A person is considered obese if they have a body mass index (BMI), which divides your weight in kilograms by your height in metres squared, of 30 or above.

Alison Tedstone, chief nutritionist at Public Health England, called obesity a complex problem that required "action across individual and societal levels involving industry, national and local government and the voluntary sector.

"Today 25 percent of the nation is obese and 37 percent is overweight," she added.

"If we reduce obesity to 1993 levels, where 15 percent of the population were obese, we will avoid five million disease cases and save the NHS alone an additional £1.2 billion by 2034."

McKinsey plans to carry out emerging world case studies in China and Mexico, but believes its recommendations will be applicable worldwide.

The report concluded that drastic action was needed "as obesity is now reaching crisis proportions".