Fat entering food during frying needs to be monitored to control the nutritional properties of the products: fat penetration and fatty acid (FA) composition. The large difference between the apparent diffusion coefficients of lipids and meat fibers allows the use of diffusion-weighted magnetic resonance imaging (DWI) to measure oil uptake profiles. This method, in association with analysis of FAs by gas-liquid chromatography. predicts nutritional changes. Beef samples from finishing cows given control feed or high FA supplemented feed were fried in olive oil at 130 degrees C and 180 degrees C. Frying oil penetration was quantified by computing oil signal profiles from 3D DWI. Oil penetration was deeper at 180 degrees C (5 mm) than at 130 degrees C (2.5 mm), consistent with oil penetration processes. Oil penetration evaluated with DWI was correlated (R-2=0.82) with biochemical analysis of FA composition. These results highlight the predominance of oil uptake over animal feed effects in the first millimeters of in-plane fried meat.