Background: Cancer cachexia is a muscle wasting syndrome characterized by anorexia, asthenia, and weight loss. Cachexia rates are as high as 35% for aggressive B-cell Non-Hodgkin Lymphomas (B-NHL), and is considered an independent factor in cancer outcomes compared to other disease burden markers. However, there remains no set protocol to identify hematologic cancer patients at risk for cachexia, and current imaging-based measures for muscle wasting can be costly and burdensome. Weight loss grading scale (WLGS) is a newly validated method to assess cachexia in solid tumor cancers but not hematologic malignancies. This study evaluates the relationship between WLGS and cancer treatment outcomes in B-NHL patients. Methods: This was a retrospective cohort study of adult patients with aggressive B-NHL treated between 2005-2020. WLGS grade was used as a cachexia marker to analyze its effect on outcomes. WLGS combines weight loss (since diagnosis) with a patient's BMI at that same time. A grade of 0 indicates no cachexia, and a grade of 4 indicates severe cachexia. Data for WLGS grade was captured for patients at 3- and 12-months post-treatment induction. Survival curve analyses assessed disability-free survival (DFS) (time from induction therapy to a patient requiring rehabilitative, home health, or skilled nursing services), progression-free survival (PFS), and overall survival (OS) outcomes. Results: Our cohort included 258 B-NHL patients. Within our study population, 45% were female, with an average age of 57 at diagnosis. B-NHL patients with higher WLGS, defined as a grade >2, composed 22% and 18% of patients at 3- and 12-months post-induction therapy, respectively. Patients with elevated WLGS were found to have significantly higher progression rates compared to lower WLGS grade individuals at 3 months (HR=1.8, p=0.049) and 12 months (HR=2.4, p=0.014) post-induction therapy. Furthermore, higher WLGS patients had significantly greater rates of disability compared with lower WLGS patients at 3 months (HR=1.7, p=0.013) and 12 months (HR=1.7 p=0.025) post-induction therapy. Finally, patients with a WLGS of 4 at 12 months post-induction therapy demonstrated significantly lower OS (HR=323, P<0.0001) than all other patients. Conclusions: In conclusion, WLGS, a new marker for cachexia, is highly correlated with morbidity and mortality outcomes in B-NHL patients. Specifically, PFS and DFS were significantly lower in groups with higher WLGS grades, and OS was significantly lower for individuals with a WLGS of 4. Weight and BMI, the two metrics used to calculate the WLGS score, require minimal time and resources to assess. Thus, regularly tracking weight can be an adjuvant screening to imaging and biomarker testing to identify patients at increased risk for disease progression or disability. The accessibility of WLGS tracking would further benefit disease tracking in resource-scarce areas and simplify disease assessment.