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Obesity diversity

LABS: One size does not fit all when treating obesity

Identifying these different groups of patients and understanding their characteristics should help obesity research and treatment

Researchers who analysed data from more than 2,400 obese patients who underwent bariatric surgery, have identified at least four different patient subgroups that diverge significantly in eating behaviours and rate of diabetes, as well as weight loss three years after surgery. This is thought to be the first study examine psychological variables - such as eating patterns, weight history and a range of biological variables, including hormone levels, to identify different types of obesity. The paper, ‘Association of Obesity Subtypes in the Longitudinal Assessment of Bariatric Surgery Study and 3-Year Postoperative Weight Change’, was published in Obesity.

Alison Field (Credit: Brown University School of Public Health)

"There probably isn't one magic bullet for obesity - if there is a magic bullet, it's going to be different for different groups of people," said Alison Field, chair of the department of epidemiology at the Brown University School of Public Health and lead author of the paper. "There's a really diverse mix of people who get put into one group. A child who becomes very obese by age 5 is going to be very different from someone who gradually gains weight over time and at age 65 is obese. We need to recognise this diversity, as it may help us to develop more personalised approaches to treating obesity."

The team used an advanced computational model, called latent class analysis, to identify different groups of patients from 2,458 adults in the Longitudinal Assessment of Bariatric Surgery (LABS) study, who underwent bariatric surgery between March 2006 and April 2009. Baseline data were used to identify subgroups and the outcome was three‐year weight change after bariatric surgery (either gastric bypass or gastric banding).

They found four distinct groups:

  • Group one was characterised by low levels of high-density lipoprotein, the so called "good" cholesterol, and very high levels of glucose in their blood prior to surgery. In fact, 98 percent of this group's members were diabetic, in contrast with the other groups, where about 30 percent were diabetic.
  • Group two was characterised by disordered eating behaviours - specifically, 37 percent had a binge eating disorder, 61 percent reported feeling a loss of control over grazing (regularly eating food between meals) and 92 percent reported eating when they were not hungry.
  • Group three were metabolically, fairly average, but they had very low levels of disordered eating - only 7 percent reported eating when they were not hungry compared to 37 percent for group one, 92 percent for group two and 29 percent for group four.
  • Group four comprised individuals who had been obese since childhood. This group had the highest BMI at age 18 with an average of 32, compared to an average of approximately 25 for the other three groups. This group also had the highest pre-surgery BMI, an average of 58 compared to approximately 45 for the other three groups.

"Interestingly, no other factors distinguished this group from the other classes," the authors reported in the paper.

Overall, in the three years following the bariatric procedure, men lost an average of 25 percent of pre-surgery weight and women lost an average of 30 percent. Field and colleagues found that patients in groups two and three benefited more from bariatric surgery than patients in groups one and four. Men and women with disordered eating lost the most, at an average of 28.5 percent and 33.3 percent, respectively, of pre-surgery weight (Figure 1).

Figure 1: (a) Weight change (%) patterns by obesity class among males in the LABS study who underwent Roux‐en‐Y bypass surgery. (b) Weight change (%) patterns by obesity class among females in the LABS study who underwent Roux‐en‐Y bypass surgery. (c) Weight change (%) patterns by obesity class among males in the LABS study who underwent gastric banding. (d) Weight change (%) patterns by obesity class among females in the LABS study who underwent gastric banding.

Identifying these different groups of patients and understanding their characteristics should help obesity research and treatment. At the ‘extreme’ end of treatment, procedures such as bariatric surgery, it's important to identify who would benefit most from surgery and those for whom the benefits likely won't outweigh the surgical risks, explained Field.

"One of the reasons why we haven't had stronger findings in the field of obesity research is that we're classifying all of these people as the same," said added. "It may very well be that there are some incredibly effective strategies out there for preventing or treating obesity, but when you mix patients of different groups together, it dilutes the effect."

Field added that obesity researchers need to test a variety of interventions in a more targeted, personalized manner. For example, mindfulness might be quite effective for people who are overstimulated by the sights and smells of food but might not be effective for people in group three who don't eat when they're not hungry, she said.

In the future, Field hopes to use the same statistical analysis methods on a more general population of overweight individuals to see if the same, or similar, subgroups exist among people at weights less than those defined as obese.

She and her colleagues are now developing a mobile app to measure what influences individuals' eating behaviours in real time. Field hopes the app can eventually be used to provide tailored interventions. She has a beta version of the app and hopes to move forward in fully developing and testing it.

“In future research, we will investigate whether longer‐term postoperative weight loss trajectories or change in comorbidity response varies across these obesity subtypes. Previous attempts to identify preoperative factors that predict weight loss and weight maintenance after bariatric surgery have been largely null; therefore, identifying subgroups of people who are undergoing bariatric surgery may help to identify those who would most benefit from bariatric surgery, as well as identify those in need of additional modalities to achieve an optimal postoperative weight change,” the authors concluded. “The current study demonstrates that, using preoperative information, one can discern obesity subtypes that have different weight change trajectories after surgery.”

To access this paper, please click here

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