From over 2,000 urine samples, levels of 29 metabolic products were found by the researchers to correlate with the body mass index of the individual.
Because the prevalence of obesity and being overweight is rising worldwide, researchers are keen to better understand the relationship obesity has to increased risk of death from heart disease, stroke, diabetes and cancer. It is estimated that obesity-driven disease results in 3.4 million deaths per year worldwide.
Scientists do not fully understand the relationship of these diseases to obesity, but they believe that by studying metabolic pathways some light may be shed on the mechanisms involved.
"Obesity has become a huge problem all over the world, threatening to overwhelm health services and drive life expectancy gains into reverse," says Prof. Jeremy Nicholson, director of the MRC-NIHR National Phenome Centre at Imperial College London and a senior author of the study.
"Tackling it is an urgent priority and it requires us to have a much better understanding of how body fat and other aspects of biology are related. These findings provide possible starting points for new approaches to preventing and treating obesity and its associated diseases," Prof. Nicholson adds.
Study identified 29 metabolites associated with obesity
Urine samples from over 2,000 volunteers in the US and UK were analyzed by the Imperial College team. From these samples, levels of 29 metabolic products were found by the researchers to correlate with the body mass index (BMI) of the individual.
As well as energy-related metabolites produced in the muscles, metabolites produced by bacteria in the gut were also linked by the study to obesity.
The researchers believe that non-obese people who have similar patterns of these metabolites in their urine may be at risk of developing obesity and metabolic diseases, and so may benefit from personalized preventative interventions.
Medical News Today asked Prof. Nicholson what was the main insight from the study in terms of understanding how obesity leads to disease. He answered:
"An important discovery is how diverse the metabolic consequences of obesity are in the body - many of the pathways we report have not been identified before and open up new lines of research. Also, the involvement of skeletal muscle metabolism and gut microbial metabolism and how they connect together has become clarified, giving us deeper biological insight into obesity. We know that the underlying microbial activity modifies gut cancer risks and so we now have some biomarkers of obesity relating to microbial metabolism that could also be cancer risk markers, but this needs to be tested."
In 2013, a study by researchers from the Kaiser Permanente Division of Research in Oakland, CA, and published in the journal PLOS ONE identified another obesity risk factor in urine.
The Kaiser Permanente researchers found that girls in the beginning and middle of puberty who had above average levels of bisphenol-A (BPA) in their urine were at twice the risk of becoming obese compared with their peers who had low levels of BPA.
BPA is an industrial chemical that has been used to make polycarbonate plastics and epoxy resins since the 1960s. These plastics and resins are commonly used in food and drink containers.