Fast spin-echo (FSE) sequences are becoming popular for T2-weighted clinical imaging because they result in a severalfold reduction in imaging time and because they provide conventional spin-echo contrast for most tissues. Fat, however, has been observed to have anomalously high signal intensity on FSE images. The present study shows that the brighter fat results from the multiple 180 degrees refocusing pulses, which eliminate diffusion-mediated susceptibility dephasing and suppress J-coupling modulation of the echo train.