Methods: A consecutive series of 141 patients who attended the neurosurgery outpatient clinic between April 2017 and September 2017 for nonspecific LBP were evaluated. Sixty-one patients with single-level Modic type I or I/II change constituted the patient group. Eighty age-, gender-, and body mass index (BMI)-matched patients without any Modic changes were recruited as the control group. A retrospective review was performed in 61 patients with Modic changes and 80 controls without Modic changes. The percentage of fatty muscle degeneration was graded by two reviewers using T2-weighted axial images at the L4–L5 level. The system was graded as follows: grade 0, normal; grade I, minimal focal or linear fat deposition; grade II, up to 25%; grade III, 25%–50%; and grade IV, more than 50%. Results: Sixty-one patients with nonspecific LBP and Modic type I or I/II change and 80 patients without Modic changes were evaluated. There was no difference between these groups in terms of age, gender, and BMI distribution. The mean muscle cross-sectional area in the patient and control groups were 1,507.37±410.63 and 1,681.64±379.69. Regarding fatty degeneration, a chi-square test of homogeneity was run, and the two multinomial probability distributions were not equal within the population analyzed. Conclusions The novel finding of this investigation is that patients with Modic type I and I/II changes have greater amounts of fatty degeneration in their lumbar paraspinal musculature.