Visceral Fat May Help ID Heart Risk in Obese Youth

The amount of fat surrounding abdominal organs may help clinicians identify cardiovascular risk in young people with obesity, researchers have found.

Severely overweight children and young adults showed a subtle association between visceral fat and arterial stiffness independent of body mass index (BMI). The association was not present in those of healthy weight, possibly because their visceral fat stores are too small to have a detectable effect on cardiovascular health, according to the researchers, who reported their findings in the latest issue of Pediatric Obesity.

Dr Joseph Kindler

“Those kids with greater visceral fat had stiffer arteries, which can overtax and overstress the system and lead to unfortunate consequences in terms of cardiovascular health down the line,” senior author Joseph M. Kindler, PhD, an assistant professor of nutritional sciences at the University of Georgia, in Athens, told Medscape Medical News.

The data came from cross-sectional measurements in 605 youth (67% female, 56% non-Black) aged 10-23 years at Cincinnati Children’s Hospital Medical Center, in Ohio. The sample included 236 individuals of healthy weight, 224 with obesity, and 145 with type 2 diabetes.    

Visceral fat was assessed with dual-energy x-ray absorptiometry (DXA), a widely used test of bone mineral density screening to assess fracture risk. Carotid-femoral pulse wave velocity (PWV) was used to gauge arterial stiffness, a subclinical sign of cardiovascular disease.

Visceral fat was associated with PWV in all three groups of study subjects (P < .05), the researchers found, whereas the amount of subcutaneous fat was linked to arterial stiffness in obese youth and those with obesity but not those whose weight was considered healthy.

The amount of fat was associated with an additional 1.6% of the variability in arterial stiffness in youth with obesity after accounting for BMI. Subcutaneous fat, meanwhile, did not appear to affect PWV, the researchers found. “In youth with healthy weight, visceral fat, subcutaneous fat, BMI, and waist circumference were not significantly associated with PWV in any analyses,” they write.

The researchers cited a paucity of data on the relationship between visceral fat and cardiovascular disease in children with obesity. Although BMI is a reliable and readily available indicator of risk for disease, DXA “might give us a little more information,” Kindler, a nutritionist and bone biologist, said. As for clinical use to supplement BMI and waist circumference, he said, “maybe there’s room for visceral fat but we do need a lot more science to back those decisions down the line.”

For example, what normal visceral fat accumulation during childhood looks like is unknown, he said.

Dr Wei Shen

Rigorous longitudinal studies are needed to establish cause and effect, but the new findings offer “a potential connection between visceral fat and cardiovascular disease risk in youth in a relatively large sample,” Wei Shen, MD, MPH, the associate director of the body composition unit at the New York Obesity Nutrition Research Center at Columbia University, New York City, said.

Ideally, said Shen, who was not involved in the latest study, it would be “more credible to use the most accurate measure of visceral fat, the volumetric measurement of visceral fat using MRI” to establish a causal relationship with cardiovascular risk. However, MRI is more expensive and less accessible than DXA. To assess visceral fat in the clinic, “waist circumference may still be a good choice, as it is so convenient to use,” she added.

Kindler and his colleagues highlighted the need to examine the effect of excess visceral fat as well as intrahepatic fat on youth with type 2 diabetes, who experience cardiovascular complications independent of whether they are obese. In the new study, the positive association between visceral fat and arterial stiffness did not differ between youth with obesity and normal glucose control and those with obesity and type 2 diabetes.

Funding came from the Endocrine Fellows Foundation, the National Institutes of Health, and the University of Georgia Obesity Initiative. Kindler and Wei have disclosed no relevant financial relationships.

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