A protocol for noninvasive quantification of dietary fat absorption in mice

Dietary fat absorption is a key determinant of energy balance, yet standard techniques to measure fat absorption are often invasive or challenging. Here, we present a protocol to non-invasively quantify intestinal fat absorption in mice during physiological feeding. We describe steps for preparing a diet containing a nonabsorbable lipid tracer and calculating fat absorption from fecal samples using gas chromatography-mass spectrometry (GC-MS), alongside complementary approaches for measuring fecal energy loss by oxygen bomb calorimetry and fecal fatty acid composition by GC-MS. For complete details on the use and execution of this protocol, please refer to Chan et al. 1