We need better classifications for obesity, a new study emphasizes.
Obesity is a major risk factor for many other health conditions, including type 2 diabetes, heart disease, and various types of cancer. This is why it is so important to find an effective therapeutic approach.
However, authors of a new study, which included data from thousands of people with obesity, warn that there is — and can be — no single best way to treat it.
The researchers — from Brown University, in Providence, RI — have found four distinct subtypes of obesity, and these may respond better to different approaches.
"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."
Lead author Prof. Alison Field
Calling for a more personalized approach
Prof. Field — who heads the epidemiology department at Brown — has been pushing for a better classification of obesity. The current diagnosis, she believes, is too broad and requires improved differentiation. This would allow doctors to identify the right treatments on an individual basis.
"There's a really diverse mix of people who get put into one group," the researcher says, adding, "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 recognize this diversity, as it may help us to develop more personalized approaches to treating obesity," she emphasizes.
The new findings, which appear in the journal Obesity, result from an analysis of data from 2,458 participants who had undergone bariatric (weight loss) surgery for obesity.
The participants had undergone either gastric bypass or gastric banding surgery between March 2006 and April 2009. The researchers recruited them via the Longitudinal Assessment of Bariatric Surgery study.
The 4 subtypes of obesity
The authors looked at the participants' psychological variables, including eating patterns, as well as their weight history and hormone levels, alongside other biological factors.
According to Prof. Field, this was the first study to include an analysis of these psychological elements.
The researchers could identify four different groups of people with obesity, using a specialized statistical method to analyze the data.
Before surgery, those in the first group had elevated levels of blood glucose (sugar) and low levels of high-density lipoprotein cholesterol, which is called "good cholesterol" because helps dispose of excess fat molecules.
As many as 98 percent of the individuals in this group had a form of diabetes.
Those in the second group had disordered eating behaviors. According to the findings:
- 37 percent of the people in this group engaged in binge eating.
- 61 percent reported feeling a lack of control over snacking between meals.
- 92 percent said that they ate when they were not hungry.
Prof. Field found the characteristics of the third group surprising. Concerning metabolism, the people in this group had fairly average obesity-consistent profiles. However, they reported very low levels of disordered eating — only 7 percent said that they ate in the absence of hunger.
"Interestingly, no other factors distinguished this group from the other classes," the researchers write.
People in the fourth group reported having received diagnoses of obesity as children. On average, those in this group had a body mass index (BMI) of 32 by age 18. This was the highest among the groups, which had a collective average of about 25 by the same age.
The members of the fourth group also had the highest average BMI, of 58, just before undergoing surgery. Those in the other groups had an average BMI of 45, recorded at the same point.
Generic classifications compromise findings
Looking at data from the first 3 years after surgery, the researchers noticed that, on average, women had lost 30 percent of their pre-surgery weight, while men had lost 25 percent.
When differentiating by groups, the team found that participants from the second and third groups experienced the greatest benefits from bariatric surgery.
Specifically, participants who had reported disordered eating habits lost the most pre-surgery weight — men an average of 28.5 percent and women an average of 33.3 percent.
These findings led Prof. Field and her colleagues to stress the importance of correctly classifying individuals with obesity, instead of grouping them all into the same indistinct category.
"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," the lead author notes.
"It may very well be that there are some incredibly effective strategies out there for preventing or treating obesity," she adds, "but when you mix patients of different groups together, it dilutes the effect."