The research, which was conducted by Professor Paul Laursen, from Auckland University of Technology, was published in the Frontiers Public Health, and uses data from the United Nations Development Programme's Human Development Report for 2014.
"The global overfat pandemic is a serious public health crisis that places a substantial burden on economic resources in developed countries. The term 'overfat' refers to the presence of excess body fat that can impair health, even for normal weight non-obese individuals," the report states.
Overfat Adults and Children in Developed Countries: The Public Health Importance of Identifying Excess Body Fat https://t.co/08a3vsGAFE— Mikki Williden (@MikkiWilliden) July 25, 2017
"The prevalence of overfat populations in 30 of the world's most developed countries is substantially higher than recent global estimations, with the largest growth due to a relatively recent increased number of people with excess abdominal fat."
The study said that if a person's waist measures more than half height then they are "overfat."
This means that more than 8 in 10 British adults are considered "overfat," and could be at risk of heart disease, cancer and diabetes.
Experts have said that the key to a long life is to have a waist less than half your height.
Being "overfat" is worse among men, with 86 percent of males suffering from the condition; women were close behind with 77 percent. 51 percent of young girls were "overfat," and 48 percent of adolescent boys.
The issue is more prevalent in developed countries, such as the UK and US.
"The prevalence of overfat populations in 30 of the world's most developed countries is substantially higher than recent global estimations, with the largest growth due to a relatively recent increased number of people with excess abdominal fat," Professor Laursen said.
"Abdominal overfat is the most unhealthy form of this condition, so it is concerning that average waist circumference measures, generally indicative of abdominal overfat, have increased.
"Despite a leveling off appearance of being overweight and/or obese in some developed countries, the overfat pandemic continues to grow," he added.