Soren Nielsen, ZengKui Guo, C. Michael Johnson, Donald D. Hensrud, and Michael D. Jensen investigated the contribution of visceral adipose tissue lipolysis to hepatic free fatty acid (FFA) delivery in obese individuals. Using isotope dilution and hepatic vein catheterization techniques, they measured systemic, splanchnic, and leg FFA kinetics in 24 obese women, 20 obese men, 12 lean women, and 12 lean men. Results showed that plasma FFA concentrations were 20% higher in obese individuals compared to lean ones. The contribution of splanchnic lipolysis to hepatic FFA delivery ranged from less than 10% to nearly 50%, increasing with visceral fat in both men and women, with a steeper slope in women. Leg and splanchnic tissues contributed more to systemic FFA release in obese individuals than in lean ones. The study concluded that visceral adipose tissue lipolysis contributes more to hepatic FFA delivery as visceral fat increases, with a greater effect in women than in men. The study aimed to assess the relationship between visceral fat and splanchnic FFA kinetics in humans. Previous studies suggested that visceral fat may contribute to metabolic complications of obesity by releasing excess FFAs into the portal vein, exposing the liver to higher FFA concentrations. The researchers used a model to predict the proportion of hepatic FFA delivery from visceral adipose tissue lipolysis, validated by comparing model predictions with measured values. The model showed a strong correlation with measured values, indicating its reliability. The study found that visceral fat area was positively correlated with the percentage of hepatic FFA delivery from visceral fat. In both men and women, the contribution of visceral lipolysis to hepatic FFA delivery increased with visceral fat, with a steeper slope in women. Leg FFA uptake was also positively correlated with plasma FFA concentrations and visceral fat area, suggesting that visceral fat plays a significant role in FFA metabolism. The study also found that leg FFA uptake was greater in obese individuals compared to lean ones, with no significant difference between men and women. However, the relationship between visceral fat and leg FFA uptake was more pronounced in women. The findings suggest that visceral adiposity contributes to abnormal FFA metabolism in two ways: excess release of FFAs from upper body subcutaneous fat and increased hepatic FFA delivery. These findings have implications for understanding the regulation of hepatic glucose and lipoprotein metabolism. The study highlights the importance of visceral adipose tissue lipolysis in hepatic FFA delivery and its potential role in the metabolic complications of obesity. The results suggest that measuring arterial plasma FFA concentrations may not reflect hepatic FFA delivery in viscerally obese individuals. The study also found that leg FFA uptake is primarily a function of plasma FFA concentrations and is increasedSoren Nielsen, ZengKui Guo, C. Michael Johnson, Donald D. Hensrud, and Michael D. Jensen investigated the contribution of visceral adipose tissue lipolysis to hepatic free fatty acid (FFA) delivery in obese individuals. Using isotope dilution and hepatic vein catheterization techniques, they measured systemic, splanchnic, and leg FFA kinetics in 24 obese women, 20 obese men, 12 lean women, and 12 lean men. Results showed that plasma FFA concentrations were 20% higher in obese individuals compared to lean ones. The contribution of splanchnic lipolysis to hepatic FFA delivery ranged from less than 10% to nearly 50%, increasing with visceral fat in both men and women, with a steeper slope in women. Leg and splanchnic tissues contributed more to systemic FFA release in obese individuals than in lean ones. The study concluded that visceral adipose tissue lipolysis contributes more to hepatic FFA delivery as visceral fat increases, with a greater effect in women than in men. The study aimed to assess the relationship between visceral fat and splanchnic FFA kinetics in humans. Previous studies suggested that visceral fat may contribute to metabolic complications of obesity by releasing excess FFAs into the portal vein, exposing the liver to higher FFA concentrations. The researchers used a model to predict the proportion of hepatic FFA delivery from visceral adipose tissue lipolysis, validated by comparing model predictions with measured values. The model showed a strong correlation with measured values, indicating its reliability. The study found that visceral fat area was positively correlated with the percentage of hepatic FFA delivery from visceral fat. In both men and women, the contribution of visceral lipolysis to hepatic FFA delivery increased with visceral fat, with a steeper slope in women. Leg FFA uptake was also positively correlated with plasma FFA concentrations and visceral fat area, suggesting that visceral fat plays a significant role in FFA metabolism. The study also found that leg FFA uptake was greater in obese individuals compared to lean ones, with no significant difference between men and women. However, the relationship between visceral fat and leg FFA uptake was more pronounced in women. The findings suggest that visceral adiposity contributes to abnormal FFA metabolism in two ways: excess release of FFAs from upper body subcutaneous fat and increased hepatic FFA delivery. These findings have implications for understanding the regulation of hepatic glucose and lipoprotein metabolism. The study highlights the importance of visceral adipose tissue lipolysis in hepatic FFA delivery and its potential role in the metabolic complications of obesity. The results suggest that measuring arterial plasma FFA concentrations may not reflect hepatic FFA delivery in viscerally obese individuals. The study also found that leg FFA uptake is primarily a function of plasma FFA concentrations and is increased