In "Is That Kosher?," Arthur suggests that if Francine has trouble with fasting, she should contact his friend, Adil, who fasts for a whole month during Ramadhan. Adil is a pen-pal of Arthur's who was introduced in the eighth season story "Dear Adil." Francine ultimately does write to Adel, who suggests that being with friends could help. Francine takes his advice, but ends up being at Arthur's when his pizza party is in full-swing.
Something to note, however, is that the monthly fast of Ramadhan is only observed during the hours from sunrise to sunset-- not actually going without food for a full month.