The World Obesity Federation (WOF) has warned that half of us will be obese or overweight by 2035. In just over a decade, more than four billion people will be overweight. There are over a billion obese people in the world today. The WHO defines obesity as "abnormal or excessive fat accumulation that presents a risk to health". A body mass index (BMI) over 30 is obese. One medical association classed obesity as a disease; others say it is a pandemic.

The WOF wants immediate action to prevent a bigger crisis. It said obesity was "particularly worrying". It urged governments to act and address the root causes so younger generations would not have to pay higher healthcare costs. The causes include an increase in the popularity of processed foods, falling levels of exercise, and a lack of health education. The WOF wants less marketing of food that has high fat and sugar content, and healthier food in schools.