I use changes in immigrant eligibility for food stamps under the 1996 federal law and heterogeneous state responses to set up a natural experiment research design to study the effect of food stamps on Body Mass Index (BMI) of adults in immigrant families. I find that in the post-1996 period food stamps use by foreign-born unmarried mothers with a high school or lower education was 10 percentage points higher in states with substitute programs than in states that implemented the federal ban. However, this increase in FSP participation was not associated with any statistically significant difference in BMI. I find that FSP participation was associated a statistically insignificant 0.3% increase in BMI among low-educated unmarried mothers.