With the exception of sub-Saharan Africa, eating too much is now a more serious risk to the health of populations than eating poorly, found the Global Burden of Disease study, published in a special edition of The Lancet.
Across the world, there has been significant success in tackling malnutrition, with deaths down two-thirds since 1990 to less than a million by 2010.
But increasing prosperity has led to expanding waistlines in countries from Colombia to Kazakhstan, as people eat more and get less everyday exercise.
Dr Majid Ezzati, chair of global environmental health at Imperial College London, and one of the lead authors of the report, said: “We have gone from a world 20 years ago where people weren’t getting enough to eat to a world now where too much food and unhealthy food – even in developing countries – is making us sick.”
Between 1990 and 2010 overall global life expectancy at birth rose by about five years. The ‘average’ boy born in 2010 can expect expect to live to 67.5 and the ‘average’ girl to 73.3.
But people are spending more of their later years in poor health, due largely to increases in diseases linked to obesity, including type II diabetes, heart disease and cancer.
Dr Christopher Murray, director of the Institute of Health Metrics and Evaluation at the University of Washington in the US, and another of the lead authors, said: “We’re finding that very few people are walking around with perfect health and that, as people age, they accumulate health conditions.”
These problems had “profound implications for health systems as they set priorities”, he said.
In the UK, male life expectancy rose from 72.9 to 77.8 from 1990 to 2010, and female life expectancy from 78.3 to 81.9.
Any individual’s death is caused by a number of interrelated factors - for example, death by stroke could be caused by high blood pressure, smoking and being overweight.
But using statistics, scientists are able to tease out one factor from the other to give estimates of how many people die from one particular cause.
Using this method, they believe being obese has risen from the 10th most important risk factor for death in 1990, to the sixth. More than three million now die from having a ‘high body mass index’ , an 82 per cent increase.
High blood pressure has risen from fourth to first, and now accounts for some nine million deaths annually.
Drinking and smoking are increasing problems too. Alcohol use rose from sixth to third and tobacco (including passive smoking) from third to second. Smoking accounted for 6.3 million deaths in 2010 and alcohol consumption 4.9 million.
But Prof Ezzati said action could be taken to address the new problems faced by doctors worldwide.
"The good news is there are lots of things we can do to reduce disease risk," he said.
"To bring down the burden of high blood pressure, we need to regulate the salt content of food, provide easier access to fresh fruits and vegetables, and strengthen primary healthcare services.”
The report noted some major improvements in the global health, most notably in children’s health.
There have been big falls since 1990 in deaths attributed to children being underweight, and to poor breastfeeding.
Child mortality (deaths under five years) dropped by almost 60 per cent between 1970 and 2010, from 16.4 million a year to 6.8 million.
There have also been significant falls in deaths attributed to poor water quality and sanitation.