O Obsession should be classified as an illness to remove the stigma that it is "self-inflicted" and to encourage those with weight problems to get help, said physicians.
When writing in the BMJ, they claimed that up to 70 percent of weight variability was inherited with 200 genes linked to it.
And the increase in obesity was due to a "changed environment", the cheap food meant was readily available.
Recent figures show that 29 percent of adults in England are overweight.
John Wilding, Professor of Medicine at the Institute for Aging and Chronic Diseases at the University of Liverpool, and Vicki Mooney, Executive Director of the European Coalition for People with Obesity, said: "Body weight, fat distribution and the risk of complications are greatly affected by biology it is not someone's fault when they develop obesity. "
"The recent rapid increase in obesity is not due to genetics but to a changed environment (food availability and costs, physical environment and social factors)."
"There are strong links to social disadvantage, some environments are more obese than others, but we should not blame individuals for the fact that the prevailing view is that obesity is caused by itself and that it is the sole responsibility of individuals to do something about it.