The researchers said the idea that weight is harmful has been"exaggerated"and people who are little heavier may actually live longer.
The California University (CU) study that looked at about 350,000 people in the US also suggested that the obese put their health in greater danger when they obsessively try to slim down.
It recommended that people should eat a varied and balanced diet, and take "enjoyable" amounts of exercise -even if they still end up carrying a few extra pounds.
The researchers also noted that society`s obsession with dieting is "ineffective" and often leads to people becoming fatter as they crave food and binge, the Daily Mail reported.
Linda Bacon, a CU professor who led the study, said that although health professionals mean well when they suggest people lose weight,"our analysis indicates that researchers have long interpreted research data through a biased lens".
"When the data are reconsidered without the common assumption that fat is harmful, it is overwhelmingly apparent that fat has been highly exaggerated as a risk for disease or decreased longevity."
The researchers also claimed that there is evidence to show that overweight people live longer than normal. Those who are obese in old age also tend to live longer than elderly people who are thin, they said.
They are also more likely to survive certain health conditions, such as type 2 diabetes, heart disease and kidney failure, added the researchers.
Although it`s known that obesity puts people at higher risk of heart disease and other illnesses, the scientists said that "being fat" is not the cause. Instead, they blame poor diet and lack of exercise -which almost always come with obesity.
Rather than obsessing with dieting, the researchers said, people would be in far better health if they learn to accept their bodies and took better care of themselves.
Besides eating a wide range of nutritious foods, they should also take regular exercise in sessions that they can enjoy and try to listen to their bodies` natural signals of being hungry and feeling full, advised the researchers who detailed their study in the Nutrition Journal.
Professor Bacon said:"For decades, the US public health establishment and USD 58.6-billion-a-year private weight-loss industry have focused on health improvement through weight loss. The result is unprecedented levels of body dissatisfaction and failure in achieving desired health outcomes."