Visceral adipose tissue accumulation thresholds for cardiometabolic risk identified by gender
Visceral adipose tissue mass does not increase linearly with adiposity, and the threshold where accumulation affected insulin sensitivity and cardiovascular risk differs by gender, according to research presented at Obesity Week 2014.
“There appears to be a threshold that occurs wherein visceral fat begins to accumulate more in the visceral region than it does in the subcutaneous regions around the body, which suggests the subcutaneous fat can’t store anymore, so it shifts it ectopically,” Tyler Bosch, PhD, a post-doctoral fellow at the University of Minnesota Medical School, told Endocrine Today. “Above those thresholds, visceral fat had a much stronger association with cardiometabolic risk factors like insulin sensitivity, triglycerides and HDL cholesterol in both males and females; below the thresholds, visceral fat didn’t have those same associations.”
In a cross-sectional design, Bosch and colleagues from the institution analyzed data from 723 adults (324 females; BMI, 15-52 kg/m2) aged 19 to 47 years to measure linearity between visceral adipose tissue (VAT) accumulation and total body adiposity to assess potential thresholds and explore associations with cardiometabolic risk factors.
The researchers used segmented linear regression to identify body fat percent thresholds in men and women at which VAT slope changed. Linear regression was used to measure the associations between VAT mass, total fat mass and subcutaneous fat and cardiometabolic risk factors above and below the thresholds.
The adiposity threshold beyond which the slope of VAT per unit of body fat percent increased to strongly positive was 23.4% body fat in men vs. 38.3% in women. For both sexes, those above the adiposity thresholds demonstrated significant dyslipidemia (P<.001), increased insulin resistance (P<.001) and higher fat mass across all depots.
“We only measured the visceral region to see this, so we don’t know if it’s actually occurring at the same time in some of the other ectopic regions,” Bosch said.
He noted they look to study these other areas more.
“There is still some debate over what type of ectopic fat accumulation is leading to changes in glucose metabolism and fat metabolism,” he said.
Bosch said women are generally believed to have better cardiometabolic risk factors than men, possibly due to a difference in subcutaneous fat storage. However, the researchers observed no between-sex differences in cardiometabolic risk factors prior to the threshold occurring, despite seeing a worse profile and more VAT in men after the threshold.
“We’re not quite sure why that is at this point,” Bosch said. “Even though it’s occurring later in terms of the amount of pecent fat, given that females generally have a little more body fat to start, it may be occurring at the same time in terms of total fat accumulation.” — by Allegra Tiver
For More Information: Bosch T. Abstract T-3095-OR. Presented at: Obesity Week; Nov 2-7, 2014; Boston.
Disclosures: Bosch reports no relevant disclosures.