When long-chain fats are carried by a protein in the blood, rat liver parts can burn them really well to make energy, even when there's a lot of fat around.

What we've found so far is that isolated rat liver mitochondria can efficiently oxidize long-chain fatty acids when they are bound to serum albumin, and this process supports energy production with high P:O ratios and respiratory control. Our analysis of the available evidence shows this ability remains effective even when fatty acid levels are high. Based on what we've reviewed so far, the mitochondria from rat liver tissue appear well-equipped to use long-chain fatty acids delivered by serum albumin as a fuel source [1]. The evidence indicates that these fatty acids are not only taken up and oxidized efficiently but also support strong energy conversion, as suggested by high P:O ratios—which reflect how well oxygen is used to produce ATP, the body’s main energy currency. Additionally, respiratory control is maintained, meaning the mitochondria regulate energy production in response to demand, a sign of healthy mitochondrial function [1]. The single assertion we analyzed, supported by 3.0 studies, consistently points in one direction: that this system works effectively under the tested conditions [1]. However, we have only reviewed a limited number of assertions so far, and our current analysis is based on a narrow set of findings. We cannot yet say how this translates to whole organisms or whether similar results occur in human tissues. Our current analysis shows the evidence leans toward efficient fatty acid oxidation in this specific experimental setup, but we recognize this is just one piece of a larger puzzle. More data would be needed to understand the full picture. Practical takeaway: In lab settings using rat liver cells, long-chain fats attached to blood proteins can be used well for energy, and the energy-making process appears efficient and well-regulated—for now, that’s what the numbers tell us.