Understanding Obesity

U of G researchers identify factors that contribute to weight-related complications

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U of G researcher David Mutch identifies factors that contribute to weight-related complications.

January is the month for New Year’s resolutions, and one of the most popular ones is to lose weight. Almost 60 per cent of adult Canadians are overweight or obese, according to Statistics Canada, so losing weight is no easy task. For some people, their genetic and molecular makeup may contribute more to their weight problem.

Researchers in U of G’s Department of Human Health and Nutrition, in collaboration with colleagues at McMaster University, recently studied participants who are at a healthy weight and those who are metabolically-healthy obese (MHO) or metabolically-unhealthy obese (MUO) to find out which factors play a role in their weight-related complications. The goal of this research is to identify factors that could be used by doctors to help better manage their patients’ body weight and risk for metabolic diseases.

Prof. David Mutch and postdoc Flavia Badoud studied metabolites in blood samples and gene expression profiles in adipose tissue from participants in the three groups to see how they differed on a molecular basis. The researchers found differences in energy metabolism and amino acid profiles between the lean group and the metabolically-unhealthy obese group. These differences were less pronounced between the lean group and the metabolically-healthy obese group.

“This shows that adipose tissue is more impaired in the ability to regulate energy metabolism in the unhealthy obese than in the healthy obese,” says Badoud. “This was mirrored in the levels of amino acids in the blood.”

Finding similarities and differences between these factors puts researchers one step closer to better understanding obesity and related health complications such as type 2 diabetes.

“We can see differences and highlight pathways that can be related to the development of insulin resistance,” she says. “Those pathways can be future targets for medications or diet interventions.”

U of G Grad Student Flavia Badoud.

U of G postdoc Flavia Badoud works in the lab.

The metabolically-healthy obese are a controversial topic among researchers, adds Mutch, since they don’t face the same obesity-related health problems as the metabolically-unhealthy obese, such as diabetes and cardiovascular disease, despite having a high body mass index and high percentage of body fat. However, he adds, the MHO group still faces a greater risk of developing other weight-related health problems, such as arthritis and sleep apnea, compared to people with a healthy weight.

“Do we need to manage these individuals differently from a health perspective?” asks Mutch.

Previous research has looked at differences in blood markers such as insulin, glucose and cholesterol between the MHO and MUO groups. “The MHO have preserved insulin sensitivity, a more healthy inflammatory state and they have a better lipid profile,” he says. But the question remains whether being MHO is a transitional or permanent state.

Identifying markers that put people at greater risk of cardiovascular disease could help doctors prescribe appropriate interventions. “It’s targeting prevention,” says Badoud, adding that the research could also help determine which patients would benefit most from costly procedures such as gastric bypass surgery and which would do best with less invasive treatment.

“There’s no one solution to solve the problem of obesity,” says Mutch. “One individual might be more responsive to a diet approach and somebody else might be more responsive to an exercise approach.”

The research was recently published in the Journal of Proteome.