The analysis of 4,144 obese people in Yorkshire showed they fitted into six distinct categories, each of which may need a different weight-loss strategy.
One example is heavy-drinking young men, according to the report published in the Journal of Public Health.
Prof Susan Jebb, from the University of Oxford, said the study did not show if the traits explained people's weight.
Around 67% of men and 57% of women are either overweight or obese according to their Body Mass Index.
"It is just a measure of height and weight and I think it generalises everyone into this one group and that's not the case really," said lead researcher Dr Mark Green at the University of Sheffield.
The team there used the Yorkshire Health Study to analyse the health and behavioural characteristics of obese people.
They said obese people, broadly, came into one of six groups:
Dr Green told the BBC News website: "I think we need to go from a one-size-fits-all approach to acknowledging there are different groups.
"We need people to think about how to tailor messages to target these different groups, the role of alcohol on body weight needs to be aimed at young males but may not be appropriate for younger females."
Prof Susan Jebb, from the University of Oxford, said: "I am the first person to say that there is huge inter-individual variation among people who are obese.
"The big limitation is that it is a cross-sectional analysis - it does not tell us if these characteristics explain why people have become overweight and it does not tell us that a particular kind of intervention would work better to treat their obesity."
Doctors need to move beyond a "one-size-fits-all" approach to tackling obesity, say scientists in Sheffield.