There are six different types of obesity, study argues

"Researchers have identified six 'types' of obese person," The Independent reports. It's argued that each type would benefit from a targeted treatment programme for obesity, rather than a "one-size-fits-all" approach.

This study looked at data from more than 4,000 obese adults taking part in the Yorkshire Health Study. It aimed to see whether it was possible to categorise obese individuals according to common health and lifestyle characteristics.

The study reported six clusters of obese individuals. These were:

• young healthy females – women who were obese, but generally had fewer obesity-related complications, such as type 2 diabetes
• heavy-drinking males – as above, but with higher alcohol intake
• unhappy and anxious middle-aged – predominantly women with poor mental health and wellbeing
• affluent and healthy elderly – generally positive health, but defining characteristics of higher alcohol intake and high blood pressure
• physically sick but happy elderly – older people with more chronic diseases such as osteoarthritis, but good mental health
• poorest health – people who were the most economically deprived and had the greatest number of chronic diseases

This research suggests it may be better to recognise subgroups of obesity, rather than put all obese people into one category, which may help tailor interventions and treatments more effectively. The current study does not prove this hypothesis, though it is worth further investigation.  

Where did the story come from?

The study was carried out by researchers from the University of Sheffield in the UK and the Harvard School of Public Health in the US. No sources of financial support are reported.

It was published in the peer-reviewed Journal of Public Health.

The UK media reports the study's findings accurately, but could, in general, do with emphasising this is theory-generating research only.

On its own, it does not provide firm evidence that there are six categories of obesity or that these people would benefit from different treatments. 

What kind of research was this?

This was an analysis of data collected as part of an ongoing UK cohort study, the Yorkshire Health Study, which aimed to see whether it was possible to categorise different subgroups of obese people according to health, sociodemographic, or behavioural characteristics.

The researchers suggest that using a single classification of obesity – simply all those with a body mass index (BMI) of 30 or over – fails to recognise the variations seen in obese people.

Some may have different levels of metabolic fitness and require different interventions. For example, some people's obesity may be related to their alcohol intake, while for others it is the result of a lack of exercise and a poor diet.

This is a useful initial study for trying to identify whether there may be different obesity types, but it can't tell us more than that. Without further study, we won't know whether these are stable subtypes with different health risks who might benefit from different treatments. 

What did the research involve?

The study used data collected from the Yorkshire Health Study between 2010 and 2012. The study aimed to examine the health needs of individuals in Yorkshire.

Participants were sent questionnaires by their GP, and data on 27,806 people (16% response rate) was collected, 4,144 of whom were obese with a BMI of 30 or more.

The questionnaire included information on age, sex, ethnicity, socioeconomic status and health conditions. A validated questionnaire (EuroQoL EQ5D) assessed health-related quality of life.

Behavioural assessments gathered information on smoking status, alcohol consumption, physical activity, and whether the person had engaged in active management of their weight, such as using slimming clubs, controlling their portion sizes, or over-the-counter remedies.

The main analysis looked for different clusters of people with common characteristics. 

What were the basic results?

The average age of the study group was 56 years, 58% were women, and the average BMI was 34. Most (95%) were white, and generally came from more deprived areas of the region.

On analysing the data, the researchers found there were six distinct clusters of obese individuals. These were defined as:

• heavy-drinking males
• younger healthy females
• physically sick but happy elderly
• affluent healthy elderly
• unhappy anxious middle-aged
• poorest health

The largest of these groups was the young healthy females, who displayed the most positive characteristics when comparing the different variables across the groups.

For example, they drank slightly less alcohol than others, had fairly good life satisfaction scores, and managed their weight slightly more actively.

Heavy-drinking males were similar to the young healthy females with the exception of their alcohol intake (average 11.86 units per week versus 4.98).

Other characteristics differed for the different groups. For example, the unhealthy anxious middle-aged predominantly included women with poor mental health, low quality of life and sense of wellbeing.

Physically sick but happy elderly included those with low levels of mental health problems but other chronic health problems, such as arthritis and high blood pressure.

The poorest health group were those who were the most deprived, and had the most chronic health problems and unhealthier lifestyle behaviour. 

How did the researchers interpret the results?

The researchers concluded that, "It is important to account for the important heterogeneity [variation] within individuals who are obese.

"Interventions introduced by clinicians and policy-makers should not target obese individuals as a whole, but tailor strategies depending upon the subgroups that individuals belong to." 

Conclusion

The researchers appropriately describe their study as being "exploratory and hypothesis-generating". The study used a large population sample of more than 4,000 obese individuals from Yorkshire.

It looked at whether there were patterns of health, sociodemographic and lifestyle characteristics that were common to these people. The study found six distinct categories that best fitted this group. However, as the researchers say, the study "may be used to drive future research" but "cannot identify causation".

The study identified six categories for this Yorkshire-based sample, but we do not know whether the same six categories would be identified if other samples of obese people were examined – for example, those of different ages, ethnicities, from different counties in the UK, or different countries. Other samples may yield fewer, more, or different categories.

Even if the different obesity categories are accurate, we can't say anything about how they relate to different health risks. For example, though some chronic diseases were more common in certain obesity categories, we can't say from this snapshot in time whether their obesity contributed to causing these diseases. By the same measure, we can't say whether any of the lifestyle characteristics measured has contributed to causing the obesity.

The study authors say all the individuals in the study would benefit from weight loss, but weight loss may not be a priority for all groups. They say, for example, that "among the poorest health group, weight loss may be less of an issue compared with the chronic health issues associated with the cluster. This is in contrast to other groups such as younger healthy females or affluent healthy elderly, where weight loss could be a priority".

However, we can't say from this research whether any of these obese groups is "healthier" or "unhealthier" than any other. Obesity is known to be associated with several adverse health effects, including risk for cardiovascular diseases and certain cancers. Research has so far not established a "healthy" type of obesity. Obesity means a weight that is unhealthy.

Although it may well be true that different types of people with obesity may respond better to different types of intervention (such as exercise interventions or behavioural support groups), this cannot be determined by this study, which has not examined different interventions.

As the researchers say, their research provides an interesting avenue for further study in ways to tackle the obesity epidemic. However, for now, the best advice is to aim for a healthy weight and lifestyle through a balanced diet, regular exercise, not smoking and moderating your alcohol intake.

Following the NHS weight loss plan may be one way you can bring your weight down to a healthy level through a combination of diet and exercise.