Obese people fall into six distinct categories, a study suggests, leading scientists to call for a new style of bespoke treatment rather than a "one size fits all" approach to tackling the epidemic.
British researchers have identified the groups as heavy drinking males, young healthy females, the affluent and healthy elderly, the physically sick but happy elderly, the unhappy and anxious middle-aged, and those with the poorest health.
The study suggests that clinicians should not target all obese people in the same way, but rather treat them according to which category they belong to.
Scientists analysed data from the Yorkshire Health Study of 4,144 obese individuals with a body mass index (BMI) of 30 or above. They identified six groups of individuals who shared common characteristics.
Those in the "heavy drinking males" group had above average levels of physical exercise but also had high levels of alcohol consumption.
Meanwhile, "younger healthy females" generally did not have many associated health problems in addition to their obesity. The researchers said that advice for young men could focus specifically on cutting down on alcohol, while young females could be told to lose weight through exercise and change of diet.
The "unhappy, anxious middle-aged" group was mainly made up of women with poor mental health and high levels of insomnia, anxiety, depression and fatigue. This group had a low sense of wellbeing and had the lowest alcohol consumption. The final three clusters showed different patterns among older people. A large proportion of the "affluent, healthy elderly" had high blood pressure and above average alcohol consumption, although this group also displayed some healthy characteristics.
The "physically sick but happy elderly" group had a higher prevalence of chronic health conditions, such as osteoarthritis, diabetes and high blood pressure, but had low levels of anxiety and depression. Those in the "poor health" group had the highest average BMI, the most chronic health conditions and tended not to engage in healthy behaviours.
Dr Mark Green, who led the study at the University of Sheffield's School of Health and Related Research, said that obese people should not be seen as one homogenous group, but rather treated in a bespoke manner according to the cluster to which they belong.
For example, the anxious middle-aged group could be advised to do more exercise and get counselling, while the poor health group may need to address their chronic health problems before tackling their obesity.
"Policies designed to tackle obesity and encourage healthier lifestyles often target individuals just because they are obese," Dr Green said. "But a focus on just the group as a whole is not very efficient. We are all different and different health promotion approaches work for different people.
"Our research showed that those in the groups that we identified are likely to need very different services, and will respond very differently to different health promotion policies."
The study, published in the Journal of Public Health, concluded that interventions by clinicians and policy-makers should not target obese people "as a whole", but use strategies tailored to suit each category.
Know your obesity type
Heavy drinking males
This group was less likely to be managing their weight, although they did report above-average levels of physical exercise and walking.
Bill, 32, is an estate agent and a regular at his local pub. Most days after work he meets up with the other regulars for a pint, or three, and his dish of choice - a steak and triple-fried chips. Friday night is a major highlight of the week, since he and his colleagues usually clock off at around 4pm to start a long night of drinking, which always ends with a late-night fry-up. On Sunday mornings he plays a game of five-a-side football, then rewards himself for his hard work with a traditional Sunday roast, always with his signature side dish of a triple Yorkshire pudding.
Younger healthy females
The study found the largest cluster was "younger healthy females", which was also the youngest group. They displayed the most positive health characteristics of all the clusters and engaged in some healthy behaviours. Nicola, 25, works in human resources at a corporate law firm. She has a sweet tooth and there is always a ready supply of chocolate, cake and biscuits at the office.
She walks to work as it is not too far from her house, but that also means she often stays out the latest drinking on weekday evenings, as she does not have far to travel home.
On Fridays and Saturdays she usually goes out drinking and clubbing with friends, or sometimes she stays in for a film and chocolate evening.
Affluent healthy elderly
The "affluent, healthy elderly" was the least deprived cluster and had positive health characteristics (although included a large proportion with high blood pressure) and above average alcohol consumption.
Susan, 65, lives life to the full. A retired solicitor with a large pension, she can afford luxuries. She has a penchant for high tea and entertains friends a few times a week at her home with scones, served with real butter, full fat cream and home-made jam. If there's any left over, Susan is more than happy to eat it for breakfast the next day. She dines out regularly, and goes on at least four cruises a year with her husband and group of friends, enjoying the all-day buffet and drink-as-much-as-you-like wine bar.
"Physically sick but happy elderly"
The "physically sick but happy elderly" group had a higher prevalence of chronic health conditions (including osteoarthritis, diabetes and high blood pressure) but exhibited low levels of anxiety and depression. Terry, 71, suffers from diabetes and high blood pressure, but he has plenty to smile about.
An avid stamp collector, he is quite content reviewing his scrapbooks and researching new items online when he feels too weak to get up. Cooking is another of his hobbies - puddings in particular (he is too old to worry about his weight anyway).
His children and grandchildren visit regularly, and often treat him to a meal at a local restaurant.
Unhappy, anxious middle-aged
The "unhappy, anxious middle-aged" group was primarily female, had poor mental health and reported high levels of insomnia, anxiety, depression and fatigue. Their sense of wellbeing was relatively low, but they did engage in healthy physical activity and weight management, and had the lowest alcohol consumption.
Wendy, 53, can't remember the last time she had a good night's sleep. She suffered from anorexia as a teenager, and struggled with depression and anxiety into her adult years. She took early retirement from her job as a social worker. Now she works as a full-time carer for her elderly father. When she can't sleep, she often goes to the kitchen and binges on junk food to cheer herself up.
The final group, made up of those with the "poorest health", was the most deprived, had the highest prevalence of most chronic health conditions, and tended not to engage in healthy behaviours. It also had the highest mean BMI.
Doreen, 43, lives on an estate with her seven children and three grandchildren. She has lung problems - she started smoking as a teenager - and doesn't get out of the house much. She's never been good at cooking and takeaways are popular with her family anyway. She often ends up looking after her grandchildren, but since they are only babies this often means just sitting around at home. During the evenings, Doreen loves a chat with neighbours over a gin and tonic.