More than 260,000 people were included in the study carried out by a Swedish-led international team of researchers.
The results, published in the Nature Genetics medical journal, show that 40 different gene variants that can increase an individual’s risk for becoming obese.
“We know from experience that genetic factors are important for the emergence of both milder and more extreme forms of obesity, but how much overlap there is between genes that are involved in extreme obesity and normal or slightly elevated BMI has not been examined systematically previously,” Erik Ingelsson, the Uppsala University professor who coordinated the study, said in a statement.
The researchers studied gene variants, or positions in the genetic code that differ between individuals. Through extensive mapping, they were able to confirm the majority of the gene loci (regions of the genome) which were already linked to various body measurements.
They also identified four new gene loci linked to height, and seven loci linked to overweight and obesity.
“Our results suggest that extremely obese individuals have a greater number of gene variants that increase the risk of obesity, rather than completely different genes being involved,” Ingelsson explained.
“This knowledge is important because it increases the biological understanding of the origins of extreme obesity as well as milder forms of obesity.”
Ingelsson added that the findings could lead to new ways of preventing and treating obesity, which he called “the greatest global public health problems of our age.”