Obesity is linked to various health complications, including diabetes and heart disease. But is the risk the same for everyone who is obese? A study revealed that the likelihood of developing obesity-related complications may vary depending on individuals' birth weights.

Children with low birth weight are at a higher risk of health complications if they develop obesity, according to the results of the latest study led by researchers from the University of Copenhagen.

"Our study shows that the link between low birth weight and cardiometabolic disease risk can be detected already in childhood – and that this is the case for both the actual birth weight and the genetic determinants of birth weight. It also supports the theory that individuals who were born low birth weight, or who are genetically predisposed to low birth weight, may be more vulnerable to health hazards – such as excess visceral fat – throughout the course of life," Sara Stinson, the first author of the study, said in a news release.

Studies have shown that children with high birth weights are more likely to be overweight or develop obesity later in life. Researchers have also known that having low birth weight or having a genetic predisposition to low birth weight raises the risk of cardiometabolic diseases like type 2 diabetes.

To further investigate the link, the research team behind the latest study evaluated a Danish cohort called The HOLBÆK Study with more than 4,000 participants. The participants were children and adolescents with or without obesity. The cohort contains a wide variety of data such as birth weight, BMI, clinical evaluations, blood samples, biomarkers, and a polygenic score for birth weight which combines the effects of many genetic variants linked to birth weight.

According to the study results published in the journal eBiomedicine, children born underweight face greater health risks if they develop obesity. For example, they would be at higher risk of developing low insulin sensitivity, a risk factor for developing diabetes.

The researchers attribute it to the mechanism by which fat gets stored in low birth weight individuals. The body typically stores fat under the skin in fat cells called subcutaneous fat. However, in children born underweight, these fat stores might be underdeveloped and hence they get stored around the organs in the form of visceral fat.

Subcutaneous fat is essential for body functioning. However, higher levels of visceral fat are linked to an increased risk of health conditions, including type 2 diabetes.

The study also revealed that low birth weight is linked to higher fat levels in the liver, reducing insulin sensitivity. This may explain why low birth weight individuals are at a higher risk of developing type 2 diabetes, even in childhood.

The researchers noted that blood samples from people with low birth weight have higher levels of obesity-related biomarkers.

Based on the study findings, the researchers call for "prevention and treatment approaches that are tailored specifically for children with obesity who were born with a lower birth weight."

"Such targeted strategies could potentially reduce their risk of developing obesity-related cardiometabolic complications," said Jens Christian Holm, co-senior author of the paper.

"Early intervention and more precision in who to treat and who not to treat are key elements in the battle of cardiometabolic disease," added Professor Torben Hansen, co-senior author of the paper.

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