The Massachusetts Medicaid and Children's Health Insurance Program launched the Flexible Services Program to address food insecurity through partnerships with social service organizations under its Section 1115 demonstration waiver. We evaluated the effects of Flexible Services Program nutritional services (or Food Is Medicine programs) on health care use and costs during the first three-year program cycle (January 2020-March 2023). Our analyses pooled data on 20,403 Flexible Services Program participants from seventeen accountable care organizations. In propensity score-weighted analyses, program participation was associated with a 23 percent reduction in hospitalizations and a 13 percent reduction in emergency department visits compared with the number of hospitalizations and visits for 2,108 eligible nonparticipants. Modestly lower health care costs for Flexible Services Program participants were not statistically significant. Health care costs were $1,721 lower among participants after the COVID-19 emergency (2022-23) and $2,502 lower among adults with more than ninety days of enrollment during all study years (2020-23). These findings are important for Medicaid policy nationwide as other state Medicaid programs pursue similar Section 1115 demonstrations.