Visceral adipose tissue (VAT), familiarly known as visceral fat, has long been associated with metabolic risk. But VAT is closely correlated with liver fat, also called intrahepatic triglyceride (IHTG) content. As a result, Samuel Klein of the Washington University School of Medicine in St. Louis, Missouri, set out to determine if liver fat is more closely correlated with complications in obese patients than VAT.
Klein and his team studied a group of 42 obese patients who were matched for age, gender, body mass index (BMI), and degree of obesity. They then divided the subjects into two groups. One group’s members had the same amount of VAT, but either high IHTG content or normal IHTG content. The other group’s members had the same IHTG content, but either high VAT or low VAT.
Using an insulin-clamp procedure, the team determined the insulin sensitivity of the participants. Of the subjects with the same VAT, those who had higher IHTG had lower insulin sensitivity: 41 percent lower in the liver, 13 percent lower in adipose tissue, and 36 percent lower in muscle. In the subjects who had similar IHTG, however, those with high VAT had the same insulin sensitivity as those who had low VAT. As a result, the researchers concluded that IHTG is a better marker than VAT for the metabolic complications of obesity.
Source: Proc Natl Acad Sci USA 2009; Abstract