Facioscapulohumeral muscular dystrophy (FSHD) is a hereditary disorder that causes progressive muscle wasting. Whole-body MRI (WBMRI) was used to scan 24 adults with genetically-confirmed type 1 FSHD. Muscles were scored for fat infiltration and edema-like changes. Fat infiltration scores were compared to muscle strength and function measurements. Our analysis reveals a distinctive pattern of muscle involvement and sparing in FSHD. Averaged fat infiltration scores for muscle groups in the legs were statistically significantly associated with quantitative muscle strength and 10-meter walk time. We conclude that WBMRI offers a promising disease biomarker in FSHD and other muscular dystrophies.